Doc #77 — Seed Preservation and Distribution

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RECOMMENDED ACTIONS

First week:

1. Confirm physical security and backup power at the Margot Forde Germplasm Centre; designate as protected national facility
2. Contact Plant & Food Research sites to confirm status of crop germplasm collections
3. Contact Kings Seeds, Yates/DLF, South Pacific Seeds, PGG Wrightson Seeds to begin inventory under Category B controlled distribution framework (Doc #1)

First month:

4. Complete commercial seed stock inventory: species, varieties, quantities, hybrid/OP status, lot ages
5. Contact NZ Heritage Food Crops Research Trust, Koanga Gardens, and known heritage seed networks; offer support for secure storage and multiplication
6. Begin germination testing of all seed stocks, prioritising short-viability species (onion, parsnip, carrot, leek)
7. Identify locations for regional seed hubs (one per region minimum)
8. Begin producing seed-saving training materials for print and distribution

First season (first planting season under nuclear winter):

9. Distribute seed to regional hubs based on food security priorities (Section 7.2)
10. Allocate a proportion of all short-viability seed species specifically for seed multiplication, not food production
11. Establish seed production plots at designated sites with proper isolation distances
12. Begin seed-saving training workshops at regional hubs, community centres, and marae
13. Plant school gardens as seed multiplication sites (Doc #158)
14. Begin field trials of all available varieties under nuclear winter conditions; record performance systematically
15. Establish community seed libraries at libraries, schools, and marae in every district

First year:

16. Harvest, process, test, and store seed from first nuclear winter growing season
17. Compile and distribute first annual seed performance bulletin: what grew, what failed, what varieties to prioritise
18. Distribute locally produced seed to expand growing network for Season 2
19. Begin duplicate dispersal of Margot Forde Germplasm Centre collections to at least two secondary sites
20. Expand seed-saving training into school curriculum (Doc #158)

Ongoing (years 2+):

21. Continue selection of locally adapted varieties from open-pollinated populations
22. Phase out reliance on stored hybrid seed as OP alternatives become available in sufficient quantity
23. Build regional seed processing infrastructure (cleaning, drying, storage) — requires seed screens or mesh (various gauges), forced-air or passive drying racks, sealed storage containers, and desiccant supply (see Section 5.3)
24. Establish seed quality standards and testing protocols
25. Maintain and expand community seed library network
26. Document and integrate Māori agricultural knowledge into the seed system

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1. NZ’S SEED INFRASTRUCTURE

1.1 The Margot Forde Germplasm Centre

The Margot Forde Germplasm Centre, located at AgResearch’s Grasslands campus in Palmerston North, is New Zealand’s primary plant genetic resource facility. It holds an estimated 75,000–85,000 accessions of grassland and forage species, including perennial ryegrass, white clover, tall fescue, cocksfoot, plantain, chicory, and other pastoral species.² This is overwhelmingly a pastoral and forage collection — it does not hold extensive vegetable or crop seed.

The Centre operates under controlled storage conditions: base collection at -20°C, active collection at 5°C and low humidity. Under these conditions, seed viability is maintained for decades to centuries depending on species.³ The facility has backup power systems, but long-term operation depends on continued grid electricity (baseline scenario: grid continues, 85%+ renewable).

This facility is a critical national asset. Its loss would be irreversible — genetic diversity accumulated over decades of NZ pastoral breeding cannot be recreated. Physical security, backup power, and redundant storage (duplicate collections at dispersed locations) should be established as immediate priorities.

1.2 The NZ Plant & Food Research collection

Plant & Food Research (formerly Crop & Food Research, HortResearch, and parts of the former DSIR) maintains research collections of fruit, vegetable, and arable crop germplasm across several sites, including Lincoln, Havelock North, and Pukekohe.⁴ These include:

• Potato cultivar collections (approximately 150–200 cultivars and breeding lines)
• Brassica breeding material
• Onion and allium collections
• Fruit crop collections (apple, kiwifruit, berry species) — relevant for long-term food diversity though not immediate caloric priority
• Grain legume material (peas, beans, lentils)

These research collections are smaller and less systematically maintained than the Margot Forde Centre but contain irreplaceable vegetable and crop genetics directly relevant to food production.

1.3 Commercial seed companies

NZ’s commercial seed supply chain includes several significant companies:⁵

• Kings Seeds (Katikati): NZ’s largest home garden seed supplier. Holds substantial stocks of vegetable and flower seed, much of it imported parent seed packaged domestically. Carries both hybrid and open-pollinated lines.
• Yates/DLF Seeds (various NZ locations): Major garden and agricultural seed supplier. Part of DLF Seeds (Danish parent company). Holds large volumes of pastoral, lawn, and vegetable seed.
• South Pacific Seeds (Canterbury): Vegetable seed production for domestic and export market. Specializes in brassicas, peas, beans, and other temperate vegetable seed. Significant seed processing and storage infrastructure.
• PGG Wrightson Seeds (Christchurch): Predominantly pastoral species — ryegrass, clover, forage crops. NZ’s largest pastoral seed company. Also handles arable crop seed (wheat, barley, oats).
• Midlands Seed (Ashburton): Vegetable seed production.
• Seed Force (Canterbury): Forage and turf seeds.

At any given time, total in-country commercial seed stocks represent one or more planting seasons of normal demand.⁶ The exact volume is commercially sensitive and not publicly reported — the national skills and asset census (Doc #8) must establish this figure as a high priority.

1.4 Canterbury’s seed production role

Canterbury is NZ’s primary seed production region, accounting for an estimated 60–70% of NZ’s domestic seed multiplication.⁷ The region’s dry summers, reliable sunshine, and established processing infrastructure (seed cleaning, drying, coating facilities) make it uniquely suited for seed production. Under nuclear winter, Canterbury’s temperatures drop to approximately 6–7°C annual average (Doc #74), severely compressing the growing season but not necessarily eliminating seed production for cold-tolerant species. Canterbury’s seed infrastructure — processing plants, seed cleaning equipment, drying facilities, storage warehouses — is a national asset second only to the germplasm collections themselves.

1.5 Retail stocks

NZ has approximately 300–400 garden centres and hardware stores (Mitre 10, Bunnings, independent garden centres) carrying retail seed packets.⁸ Individual stores carry modest volumes, but in aggregate this represents a meaningful distributed seed reserve. These stocks are predominantly hybrid cultivars — the seed companies supply what home gardeners want, which is high-performing F1 hybrids. The open-pollinated proportion is probably 15–30% of retail vegetable seed lines, though this varies by crop and company.⁹

1.6 Farmer-saved seed

NZ arable farmers routinely save seed grain (wheat, barley, oats) from their own harvest for replanting. This practice is well-established for cereal crops and represents a functional seed sovereignty model for grains.¹⁰ Farmer-saved vegetable seed is less common — most commercial vegetable growers plant purchased hybrid seed each season. Some pastoral farmers save ryegrass and clover seed, though most purchase from commercial suppliers.

1.7 Home gardeners and heritage networks

NZ has a substantial home gardening population and several organizations maintaining heritage and open-pollinated seed collections:

• NZ Heritage Food Crops Research Trust (Whanganui): Maintains a collection of heritage vegetable, fruit, and grain varieties, many open-pollinated. Distributes seed to members.
• Koanga Gardens (Wairoa): Heritage seed supplier specializing in open-pollinated vegetable, herb, and flower varieties adapted to NZ conditions. Holds one of NZ’s most significant collections of open-pollinated vegetable genetics.¹¹
• Southern Seed Exchange and various regional seed-swap networks.
• Individual gardeners maintaining their own seed-saving practices.

These collections are small in volume but disproportionately valuable because they hold open-pollinated genetics that breed true — the essential foundation for long-term seed sovereignty (see Section 4).

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2. WHY SEEDS MATTER DISPROPORTIONATELY

2.1 The multiplication ratio

Seeds have a multiplication ratio unmatched by any other resource:

Crop	Approx. seeds per gram	Yield per plant (kg)	Multiplication ratio (food kg per gram of seed)
Lettuce	700	0.3–0.5	200–350
Tomato	300	2–5	600–1,500
Cabbage	250	1–3	250–750
Carrot	800	0.1–0.3	80–240
Potato (from true seed)	1,000+	0.5–2	500–2,000
Wheat	25–30	0.003 per seed (30 seeds/head)	~30x by weight
Broad bean	1–2	0.5–1	~1–2 per seed

These figures are approximate and assume reasonable growing conditions. Under nuclear winter, yields are reduced — but the multiplication principle holds. One kilogram of well-chosen vegetable seed, properly distributed and grown, can produce tens of thousands of kilograms of food under reasonable growing conditions.¹²

2.2 Irreversibility of genetic loss

Most stockpile items (fuel, tires, pharmaceuticals) are consumed and gone. Seeds are self-renewing — but only if the genetic lines are maintained. If a crop variety is lost (all seed consumed, no plants grown to maturity for seed saving), it is gone permanently. This is not like running out of toner, where the loss is inconvenient but recoverable if supply resumes. Genetic loss is irreversible.

This means seed preservation decisions made in the first months have consequences that compound for decades. Using all available seed of a variety for food production in Year 1, without retaining seed stock for future planting, is a catastrophic error — even if the food is needed. Some seed of every viable variety must be held back from consumption under all circumstances.

2.3 Diversity as insurance

Under nuclear winter, growing conditions change in ways that are difficult to predict precisely. A variety that performs well in normal NZ conditions may fail under colder, darker conditions — and a variety that was marginal before may prove well-adapted. Maintaining the widest possible genetic diversity is insurance against uncertainty. Narrowing the seed base to a few “best” varieties is a gamble that those varieties will perform under conditions no one has tested them in.

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3. THE NZ PLANTING CALENDAR UNDER NUCLEAR WINTER

3.1 Normal NZ growing calendar

NZ’s temperate maritime climate allows year-round growing in the North Island and a growing season of approximately September–April in most of the South Island. Key planting periods (North Island, temperate regions):¹³

• Spring (September–November): Main planting season for most crops. Potatoes, brassicas, peas, beans, lettuce, root vegetables, onion seedlings.
• Summer (December–February): Heat-loving crops established. Tomatoes, peppers, corn, cucumbers, beans. Succession planting of salad crops.
• Autumn (March–May): Overwintering crops planted. Garlic, broad beans, peas, brassicas for spring harvest, onion sets.
• Winter (June–August): Limited planting except in frost-free areas. Garlic (already in ground), broad beans, winter-hardy brassicas.

3.2 Shifted calendar under approximately 5°C cooling

A 5°C drop shifts NZ’s effective growing climate roughly southward by several hundred kilometres, or equivalently, backward/forward in the seasonal calendar by an estimated 4–8 weeks.¹⁴ Practically:

• Northern North Island (Auckland, Waikato, Bay of Plenty): Becomes similar to current Canterbury/Southland climate. Year-round growth of cold-hardy crops is still possible but summer warmth is marginal for heat-loving crops.
• Southern North Island (Wellington, Manawatu, Wairarapa): Growing season compressed to approximately October–March. Winter growth stops.
• Canterbury Plains: Growing season compressed to approximately November–February. Frost-free period shortened dramatically. Most outdoor cropping limited to fast-maturing cold-tolerant species.
• Southland/Otago: Marginal for most cropping. Very short growing season. Greenhouse production (Doc #79) may be necessary for anything beyond the hardiest crops.

3.3 Implications for seed timing

The critical constraint is not seed availability but planting window. If the event occurs in NZ autumn or winter (March–August), there are months before the next main planting season to inventory, distribute, and plan. If the event occurs in spring or summer (September–February), the current growing season is disrupted and the next planting opportunity is months away regardless.

In either case, the first nuclear winter planting season is the critical deadline. Missing it means no domestically grown food for an additional 6–12 months — an unacceptable delay. All seed distribution and growing guidance must be in place before the first planting season under nuclear winter conditions.

3.4 What can still be grown outdoors

Under approximately 5°C cooling, the following crops remain viable outdoors in most of the North Island and northern South Island:

High confidence (cold-tolerant, well-adapted to NZ):

• Potatoes (including early and maincrop varieties)
• Brassicas: cabbage, kale, broccoli, Brussels sprouts, cauliflower, turnips, swedes
• Root vegetables: carrots, parsnips, beetroot
• Alliums: onions, garlic, leeks
• Leafy greens: silver beet (chard), spinach, lettuce (cool-season types)
• Legumes: broad beans, peas
• Grains: wheat, barley, oats (if growing season allows maturation)

Moderate confidence (need warm period, marginal under cooling):

• French/runner beans (shorter season varieties only)
• Sweet corn/maize (only in warmest regions, short-season varieties)
• Pumpkin/squash (some varieties, North Island only)

Low confidence outdoors (require greenhouse — Doc #79):

• Tomatoes
• Peppers/capsicums
• Cucumbers, courgettes
• Kumara (sweet potato)

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4. THE HYBRID SEED PROBLEM

4.1 Why this matters

The majority of commercial vegetable seed sold in NZ is F1 hybrid.¹⁵ Hybrid seed is produced by crossing two inbred parent lines, producing offspring with “hybrid vigour” — higher yields, greater uniformity, and often disease resistance. This is why commercial growers and home gardeners prefer hybrid cultivars.

The problem: seed saved from F1 hybrid plants does not breed true. The second generation (F2) segregates — plants show a wide range of characteristics, many inferior to the F1 parent, some potentially useful but unpredictable. For a food system that depends on reliable production, planting F2 seed from hybrids is a gamble.

4.2 The scale of the problem

For many key vegetable crops, open-pollinated varieties represent a minority of the commercially available seed in NZ:

Crop	Estimated OP varieties available in NZ (%)	Hybrid dominance
Tomato	20–30%	High — most commercial and retail seed is hybrid
Cabbage/broccoli/cauliflower	10–20%	Very high — almost all commercial production uses hybrids
Onion	30–40%	High for modern varieties
Carrot	20–30%	High
Lettuce	40–60%	Moderate — many OP types still in commerce
Peas	70–90%	Low — most pea varieties are OP or stabilized lines
Beans	60–80%	Low to moderate
Potato	N/A (vegetatively propagated)	Not applicable — potatoes are grown from tubers, not true seed
Sweet corn	5–15%	Very high

These are estimates. Exact proportions would need to be established through inventory of actual NZ seed stocks.¹⁶

4.3 The transition timeline

Transitioning from hybrid to open-pollinated seed sovereignty takes multiple growing seasons:

Season 1: Plant whatever is available — hybrid or OP. The priority is food production. Begin identifying and isolating OP varieties for seed saving.

Season 2: Plant saved OP seed alongside remaining commercial stock. Continue selecting and saving seed from the best OP performers. F2 seed from hybrids can be planted experimentally, with the understanding that yields typically drop 20–50% compared to the F1 parent, uniformity is lost (wide variation in plant size, maturity, and fruit quality), and some plants may revert to unproductive parental types.¹⁷

Season 3–5: OP lines stabilize through continued selection. Locally adapted populations develop as growers select for performance under actual nuclear winter conditions. Hybrid seed stocks are exhausted; OP seed production becomes the norm.

This transition is feasible but not trivial. It requires a national commitment to seed saving education, starting immediately (see Section 8).

4.4 Heritage seed collections as the genetic bridge

The NZ Heritage Food Crops Research Trust, Koanga Gardens, and individual seed savers hold the open-pollinated genetics that NZ’s long-term seed sovereignty depends on. These collections are small — perhaps hundreds of packets or jars of seed, compared to the tonnes held by commercial companies — but they contain the genetics that breed true.

These collections must be identified, protected, and multiplied as a top priority. A single packet of open-pollinated tomato seed from Koanga Gardens is worth more to NZ’s long-term food system than a pallet of hybrid tomato seed from a commercial supplier, because only the OP seed can reproduce indefinitely.

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5. SEED VIABILITY AND STORAGE

5.1 How long seeds last

Seed viability is not binary — it declines over time, with the rate depending on species, initial seed quality, and storage conditions. Approximate viability under good storage conditions (cool, dry, dark):¹⁸

Crop family	Example crops	Approx. viability (years, >70% germination)
Alliums	Onion, leek	1–2
Umbellifers	Carrot, parsnip, parsley	1–3
Legumes	Peas, beans, broad beans	3–5
Brassicas	Cabbage, broccoli, kale, turnip, radish	4–5
Solanaceae	Tomato, pepper, eggplant	4–6
Cucurbits	Pumpkin, cucumber, courgette	4–6
Lettuce/Compositae	Lettuce, endive	3–5
Cereals	Wheat, barley, oats	3–8 (varies widely)
Grasses	Ryegrass, fescue	3–5

Critical implication: Onion and leek seed loses viability rapidly — after 2 years, germination may drop below useful levels. Any onion seed in NZ at the time of the event must be planted or properly stored within the first 1–2 seasons or it will be lost. Onion seed production must begin immediately. By contrast, tomato seed stored well can last 5–6 years, providing more time for the transition.

5.2 Orthodox versus recalcitrant seeds

Most vegetable and crop seeds are “orthodox” — they tolerate drying and storage at low moisture content and low temperature, and viability is extended by cooler, drier conditions. This is fortunate, as it means conventional storage works.

A few NZ-relevant species have “recalcitrant” or intermediate seed that does not tolerate drying: notably some native forest species and tropical crops. For food production crops, the main exception is that potatoes are propagated vegetatively (tubers, not true seed), and kumara is propagated from shoots (tipu). These crops require living plant material to be maintained, not just dry seed in storage.

5.3 Storage conditions

The key factors for seed longevity are:¹⁹

• Moisture content: The single most important factor. Seed moisture content should be 5–8% for most species. Above 12–14%, fungal growth and seed deterioration accelerate rapidly. Each 1% reduction in seed moisture content approximately doubles storage life (Harrington’s rule of thumb).
• Temperature: Each 5°C reduction in storage temperature approximately doubles storage life (Harrington’s rule of thumb). The Margot Forde Centre stores base collections at -20°C for this reason. For community-level storage, a cool room, cellar, or refrigerator is adequate.
• Light: Not critical in sealed containers, but prolonged light exposure can reduce viability of some species.
• Oxygen: Reduced oxygen (sealed containers, vacuum packing) extends viability but is not essential for medium-term storage.

NZ-specific challenge: The North Island, particularly Northland, Waikato, and Bay of Plenty, has high ambient humidity. Seed stored in open containers in these regions absorbs moisture and deteriorates quickly. Sealed containers with desiccant are essential for seed storage in humid regions. Commercial silica gel (available from packaging salvage and craft suppliers) is the most effective option; powdered milk and dry rice are improvised alternatives but absorb less moisture per gram and must be replaced more frequently.²⁰ The sealed containers themselves require glass jars with rubber-seal lids, or plastic containers with tight-fitting lids — both drawn from existing NZ household and commercial stocks, not manufactured domestically at scale.

5.4 Germination testing

All seed lots should be tested for germination before reliance is placed on them. The method is simple and requires no special equipment:

1. Count out a known number of seeds (20, 50, or 100)
2. Place on moist paper towel, cloth, or between sheets of damp newspaper
3. Keep warm (15–25°C) and moist but not waterlogged
4. Count germinated seeds after the species-appropriate period (3–14 days depending on crop)
5. Calculate germination percentage

A germination rate above 70–80% is generally acceptable for planting. Below 50%, increase seeding rate to compensate. Below 20%, the seed lot is marginal — plant if nothing better is available, but do not rely on it.

This testing should be standard practice for all distributed seed. Every seed packet, bag, or container should have a germination test result before distribution to growers.

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6. SEED SAVING FUNDAMENTALS

6.1 Why this section exists

Seed saving was a universal farming skill until the mid-20th century. The commercial seed industry has made it largely unnecessary for farmers and gardeners, and the knowledge has been substantially lost.²¹ Under permanent trade isolation, NZ must rebuild this knowledge base across thousands of growers within a few seasons. This section provides the essential technical framework. Detailed crop-by-crop guides should be produced and distributed as part of the Recovery Library printing program, and incorporated into the school curriculum (Doc #158).

6.2 Pollination biology: the foundation

The single most important concept in seed saving is pollination biology, because it determines whether saved seed will breed true.

Self-pollinating crops: Flowers pollinate themselves before opening, or shortly after. Cross-pollination occurs at low rates (typically 1–5%). Seed saved from these crops breeds reasonably true without isolation. Key self-pollinating food crops:

• Tomatoes
• Peas
• Beans (French beans, runner beans — though runner beans cross more readily)
• Lettuce
• Wheat, barley, oats

Cross-pollinating crops: Flowers require or strongly prefer pollen from other plants, carried by wind or insects. Seed saved from these crops without isolation will be cross-pollinated, producing variable offspring. Key cross-pollinating food crops:

• All brassicas (cabbage, kale, broccoli, cauliflower, turnip, radish, swede — and they cross with each other)
• Onions, leeks
• Carrots, parsnips
• Beetroot, silver beet (chard) — these two cross with each other
• Sweet corn/maize (wind-pollinated)
• Pumpkins, squash (insect-pollinated; different species can be grown together, but varieties within the same species cross)
• Ryegrass, clover, and most pasture species

6.3 Isolation distances

Cross-pollinating crops must be isolated from other varieties of the same species to produce true-breeding seed. Required isolation distances vary:²²

Crop	Pollination method	Minimum isolation distance (metres)	Notes
Brassicas	Insect	500–1,600	All Brassica oleracea species cross: cabbage, kale, broccoli, cauliflower, kohlrabi, Brussels sprouts
Carrot	Insect	300–1,000	Crosses with wild carrot (Queen Anne’s lace)
Onion	Insect	500–1,600
Beetroot/silver beet	Wind	500–1,600	Beta vulgaris — beet and chard cross freely
Sweet corn	Wind	300–500
Pumpkin/squash	Insect	500+ within species	Different Cucurbita species do not cross
Tomato	Self	10–50	Largely self-pollinating; minimal isolation needed
Peas	Self	5–10	Very high self-pollination rate
Beans	Self/insect	20–100	Runner beans need more isolation than French beans

The brassica problem: Because all Brassica oleracea species (cabbage, kale, broccoli, cauliflower, Brussels sprouts, kohlrabi) cross-pollinate freely, a community cannot save true seed from more than one of these crops unless they are separated by 500+ metres or their flowering periods do not overlap. This is a genuine logistical constraint for seed saving programs and must be coordinated at a regional level.

6.4 Selection criteria

Seed should be saved from the best-performing plants, not from whatever happens to be left at harvest. Selection criteria for nuclear winter conditions should prioritize:

1. Cold tolerance: Plants that establish and produce well under cooler conditions
2. Early maturity: Varieties that complete their growth cycle within the shortened season
3. Vigour under low light: Plants that grow actively despite reduced sunlight
4. Disease resistance: Without reliable access to fungicides and pesticides, genetic resistance becomes critical
5. Yield: Still important, but secondary to survival traits under stress conditions
6. Seed production: Plants that produce abundant, viable seed (not all high-yielding food plants are good seed producers)

Mark your best plants before harvest. The natural temptation is to eat the best produce and save seed from whatever is left — this is selection in reverse. Tag or mark the best-performing plants early in the season and let them go to seed rather than harvesting for food.

6.5 Seed processing

Dry processing (most crops): Brassicas, beans, peas, grains, lettuce, carrots, onions, and most other crops produce dry seed in pods, heads, or umbels. Allow seed heads to dry on the plant as long as weather permits, then cut and finish drying under cover. Thresh (separate seed from chaff) by hand, flailing, or rubbing. Winnow (blow or fan away chaff). For small quantities, rubbing seed heads between hands and blowing gently is adequate.

Wet processing (tomatoes, cucumbers, some cucurbits): Scoop seeds and surrounding gel from ripe fruit into a container. Add a small amount of water. Allow to ferment for 2–3 days at room temperature — this breaks down the germination-inhibiting gel coating and kills some seed-borne diseases.²³ The good seeds sink; pour off the floating pulp and dead seeds. Rinse clean seeds thoroughly and dry.

6.6 Drying

Proper drying is critical. Seeds that are stored too moist will rot, grow mould, or lose viability rapidly.

Target moisture content: 5–8% for most species. Seeds at this moisture content feel hard and brittle; they snap rather than bend. Bean and pea seeds shatter when hit with a hammer rather than denting.

Drying method: Spread seeds in a thin layer on screens, trays, or newspaper in a warm, dry, well-ventilated location out of direct sunlight. In NZ’s humid regions, supplementary drying with gentle heat (30–35°C maximum — temperatures above 40°C damage most vegetable seeds, and above 50°C kill them outright)²⁴ or with desiccant in a sealed container may be necessary. Silica gel (available from craft suppliers, or salvage from packaging) is effective.

Drying duration: 1–3 weeks depending on conditions and seed size. Large seeds (beans, peas, corn) take longer than small seeds (lettuce, carrot).

6.7 Biennial crops

Some important food crops are biennial — they grow vegetatively in Year 1 and produce seed in Year 2. This complicates seed saving because the plants must survive through winter:

• Carrots, parsnips: Grow roots in Year 1. Overwinter roots in ground (or lift and store in cool moist sand). Replant in spring; they bolt and produce seed in Year 2.
• Onions, leeks: Grow bulbs in Year 1. Overwinter; plant out and they produce seed heads in Year 2.
• Brassicas (cabbage, kale, broccoli, turnips, swedes): Grow the food crop in Year 1. Overwinter the best plants. They bolt and flower in Year 2.
• Beetroot, silver beet: Biennial; overwinter and produce seed in Year 2.

Under nuclear winter, the cold winters may kill biennial plants that normally overwinter in the ground in NZ. Root crops may need to be lifted and stored indoors (in cellars, root stores, or cold frames) and replanted in spring. This adds labour and storage requirements to seed production.

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7. NATIONAL SEED STRATEGY

7.1 Phase 1: Secure and inventory (first weeks to months)

Secure the Margot Forde Germplasm Centre.

• Confirm physical security, backup power, and staffing
• Establish as a protected national facility with 24-hour site management
• Begin creating duplicate collections for dispersal to secondary sites (at minimum, one North Island and one South Island backup location)

Inventory all commercial seed stocks.

• Category B controlled distribution (Doc #1): commercial seed stocks remain with the seed companies but under government allocation direction
• Complete inventory of species, varieties, quantities, lot ages, and germination test results
• Distinguish open-pollinated from hybrid seed — this information is critical for long-term planning and is not always clear on commercial packaging
• The skills and asset census (Doc #8) should specifically identify holders of traditional agricultural knowledge (including kūmara cultivation, seed selection, and food storage techniques) as a critical human resource

Identify and protect heritage seed collections.

• Contact NZ Heritage Food Crops Research Trust, Koanga Gardens, and known seed-saving networks
• Offer government support for secure storage and multiplication
• Do not requisition personal seed collections — this would destroy the community trust that makes seed networks function. Incentivize voluntary registration and multiplication instead (Doc #1, Category C)

Conduct germination testing.

• Prioritise oldest seed lots and species with short viability (onions, carrots, parsnips)
• Every seed lot distributed should carry a germination test result

7.2 Phase 1–2: Distribute and plant (before first planting season)

Distribute seed based on food security priorities, not pre-event commercial demand. Normal commercial seed distribution allocates by market demand — home gardeners buy what they want to grow, farmers buy what is profitable. Under nuclear winter, allocation must prioritise:

1. Caloric density: potatoes, grains, broad beans, peas
2. Nutritional diversity: brassicas (vitamin C, calcium), carrots (vitamin A), alliums, leafy greens
3. Cold tolerance: varieties suited to nuclear winter conditions
4. Seed-saving potential: open-pollinated varieties that can be multiplied

Establish regional seed hubs. At least one per region (aligned with existing regional council boundaries), responsible for:

• Receiving and storing allocated seed
• Distributing to local growers
• Coordinating isolation distances for seed production (Section 6.3)
• Collecting and testing locally produced seed
• Training seed savers (Section 8)

Logical locations for regional seed hubs include existing agricultural research stations, rural schools, and council depots.

Prioritise seed multiplication for short-viability species. Onion, leek, carrot, and parsnip seed must be planted and multiplied within the first 1–2 seasons or the existing stocks lose viability and the genetics are lost. Allocate a proportion of these seeds specifically for seed production, not food production, even though this means less food in Year 1.

7.3 Phase 2–3: Build seed sovereignty (years 1–5)

Transition from hybrid to open-pollinated genetics. Systematically identify, multiply, and distribute open-pollinated varieties of all key crops. Use heritage collections as the foundation. Select for nuclear winter performance.

Develop locally adapted populations. Encourage growers in each region to select seed from their best performers. Over 3–5 generations of selection, locally adapted varieties emerge that are suited to the specific conditions of that region under nuclear winter.²⁵ This is classical plant breeding, practiced by farmers for thousands of years, and it works.

Establish formal seed quality standards. As the seed system matures, implement minimum standards for germination rate, varietal purity, and seed health. Initially these can be simple (germination test + visual inspection); over time, more formal testing can be developed.

Document and share. Every variety, every selection, every observed performance under nuclear winter conditions should be recorded. This data feeds back into varietal recommendations for subsequent seasons. The Recovery Library should include an annual seed performance bulletin.

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8. PRIORITY CROP LIST FOR NUCLEAR WINTER NZ

The following table prioritises crops for NZ food security under nuclear winter conditions. Ratings are the author’s assessment and should be updated based on field observation.

Crop	Why important	Seed viability (years)	Outdoor growing (nuclear winter)	Seed saving difficulty	Notes
Potato	Highest caloric yield per hectare; cold-tolerant	N/A (tubers)	High confidence	Easy (save tubers)	Blight risk increases in cool wet conditions. Save small healthy tubers as seed
Cabbage	Vitamin C, stores well, extremely cold-hardy	4–5	High confidence	Moderate (biennial, crosses with other brassicas)	Multiple varieties for succession: early, mid, late, storage types
Kale	Very cold-hardy, high nutrition, cut-and-come-again	4–5	High confidence	Moderate (biennial, crosses)	Possibly the single most reliable leafy green under nuclear winter
Broad bean	Protein, nitrogen fixation, cold-tolerant	3–5	High confidence	Easy (self-pollinating, dry seed)	Autumn or spring sowing. Staple protein source
Peas	Protein, nitrogen fixation	3–5	High confidence	Easy (self-pollinating, dry seed)	Spring sowing. Both shelling and snow pea types valuable
Wheat	Staple carbohydrate, stores well	3–8	Moderate (needs season length)	Easy (self-pollinating, dry seed)	Autumn-sown varieties may be more reliable under shorter growing season
Barley	Staple carbohydrate, shorter season than wheat	3–8	Moderate–high confidence	Easy	Earlier maturity than wheat is an advantage
Oats	Carbohydrate, cold-tolerant	3–5	Moderate–high confidence	Easy	Tolerates poorer soils than wheat
Onion	Flavour, nutrition, stores well	1–2	High confidence	Moderate (biennial, cross-pollinating)	Short seed viability — multiply immediately
Garlic	Flavour, health properties, stores well	N/A (cloves)	High confidence	Easy (save best bulbs)	Plant autumn for summer harvest
Carrot	Vitamin A (beta-carotene), stores well	1–3	High confidence	Moderate (biennial, crosses with wild carrot)	Short seed viability — prioritise multiplication
Parsnip	Cold-hardy, high calorie root	1–2	High confidence	Moderate (biennial)	Very short seed viability — multiply immediately
Turnip/swede	Fast-growing, cold-hardy, dual-use (human food and livestock)	4–5	High confidence	Moderate (biennial, brassica crosses)	Swede stores better than turnip
Silver beet	Reliable leafy green, cold-tolerant	4–5	High confidence	Moderate (biennial, crosses with beetroot)	Cut-and-come-again harvest
Spinach	Nutrient-dense, cold-tolerant	3–5	High confidence	Easy–moderate (wind-pollinated, needs isolation)	Bolts in long days; suited to spring/autumn growing
Beetroot	Calorie-dense root, stores well	4–5	High confidence	Moderate (biennial, crosses with silver beet)	Both root and leaves edible
Lettuce	Fresh salad, vitamin-rich	3–5	Moderate–high	Easy (self-pollinating)	Cool-season types well-suited to nuclear winter
Pumpkin/squash	Calorie-dense, stores months	4–6	Low–moderate (needs warm season)	Easy (dry seed from fruit)	Crown pumpkin, buttercup, butternut — North Island only under nuclear winter
Tomato	Vitamin C, versatile	4–6	Low (greenhouse required)	Easy (self-pollinating, wet process)	Priority greenhouse crop (Doc #79)

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9. HERITAGE CROP GENETICS: KŪMARA AND TAEWA

9.1 Kūmara (sweet potato)

Kūmara (Ipomoea batatas) was the primary carbohydrate crop of pre-European Māori agriculture and NZ’s most important traditional food plant. Māori developed sophisticated kūmara cultivation systems at the southern limit of the crop’s global range, including:²⁶

• Selection of cold-tolerant lines: Māori kūmara varieties (especially traditional taewa types) are adapted to NZ’s relatively cool conditions compared to tropical sweet potato
• Raised gravel beds (māra kūmara): Stone-lined garden plots that improved drainage and heat retention
• Underground storage pits (rua kūmara): Purpose-built subterranean stores maintained at cool, stable temperatures for overwintering tubers
• Careful tuber selection: Saving the best tubers from the best-performing plants for next season’s planting

Under nuclear winter, outdoor kūmara cultivation is almost certainly unviable even in Northland — the crop requires warm soils (minimum 15–18°C) and a frost-free growing season of 4–5 months.²⁷ However, kūmara production in greenhouses (Doc #79) or under row cover/cloche systems remains feasible, and the traditional Māori knowledge of kūmara selection, storage, and cultivation at the margin of viability is directly applicable.

The surviving kūmara cultivar collections — held by Plant & Food Research, Koanga Gardens, and Māori growers — must be protected. If kūmara genetics are lost, they cannot be replaced from overseas under trade isolation.

9.2 Māori potatoes (taewa)

Māori potato varieties, introduced in the late 18th century and selected over 200+ years for NZ conditions, represent a distinct genetic resource. Over 40 named taewa varieties have been documented.²⁸ Many are small-tubered, colourful, and strongly flavoured — characteristics that made them commercially uncompetitive but which may include traits (cold tolerance, disease resistance, flavour under stress) useful under nuclear winter conditions. The Tahuri Whenua National Māori Vegetable Growers Collective and some Māori communities maintain taewa collections. Other traditional Māori crops — including tī kōuka (cabbage tree, Cordyline australis) grown for its edible root and heart, and hue (gourd) — represent additional genetic resources that may have recovery-era value and should be documented through the heritage crop inventory.²⁹

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10. COMMUNITY SEED LIBRARIES AND NETWORKS

10.1 Why distributed networks matter

A centralised seed system — one national depot distributing seed to all growers — is efficient but fragile. A single fire, flood, pest incursion, or administrative failure can destroy the entire stock. Distributed seed networks, where many communities hold and multiply their own seed, are resilient through redundancy. If one community’s seed stock fails, others can resupply.

10.2 Structure of community seed libraries

A community seed library operates on a simple model:

1. Growers take seed from the library at planting time
2. Growers return seed (of equal or greater quantity, with germination test) after harvest
3. The library maintains records of what is held, what is distributed, and what is returned
4. A trained seed librarian manages storage conditions, germination testing, and variety records

Community seed libraries can be hosted at: public libraries, schools, community halls, marae, rural supply stores, or any community facility with dry, cool storage space.

10.3 School gardens as multiplication sites

NZ has approximately 2,400–2,600 schools, most with grounds suitable for garden plots.³⁰ Under the revised school curriculum (Doc #158), practical food growing and seed saving become core skills. School gardens serve a dual purpose:

• Education: Students learn seed saving, plant biology, and food production — skills that NZ needs to rebuild at population scale
• Seed multiplication: Each school garden produces seed as well as food, contributing to the regional seed supply

A school garden growing four varieties of open-pollinated vegetables, with proper isolation and seed saving, can produce 1–5 kg of seed per season depending on species and garden size — enough to supply 20–50 home gardens for those crops.³¹ Across 2,500 schools, this represents a national seed multiplication infrastructure embedded in every community.

10.4 Coordination with regional seed hubs

Community seed libraries and school gardens feed into the regional seed hub structure (Section 7.2). The hub provides:

• Seed of new varieties for distribution to community libraries
• Quality testing and feedback on locally produced seed
• Coordination of isolation distances (ensuring neighbouring communities are not growing seed crops of the same brassica species, for example)
• Training and technical support

The hub does not replace community seed saving — it supports and coordinates it. The goal is distributed capacity with light coordination, not centralised control.

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CRITICAL UNCERTAINTIES

Uncertainty	Impact if Wrong	Resolution Method
Proportion of OP vs hybrid in NZ commercial seed stocks	If lower than estimated, seed sovereignty transition takes longer and is more difficult	Inventory of actual seed stocks (Doc #8 census)
Crop performance under nuclear winter conditions	If worse than expected, food production falls short; if better, more options are available	Field trials in first growing season; systematic performance recording
Seed viability of existing stocks	Older seed lots may have lower germination than assumed	Systematic germination testing of all stocks
Availability and willingness of heritage seed network holders	If key collections are lost or holders do not cooperate, OP genetics are reduced	Early contact and relationship-building; incentivise cooperation (Doc #1, Category C)
Pollinator populations under nuclear winter	Reduced insect pollination affects seed set for cross-pollinating crops	Monitor; develop hand-pollination protocols as backup
Extent of farmer seed-saving knowledge	If less than assumed, training takes longer to reach effective skill levels	Assess through Doc #8 skills census; scale training accordingly
UV effects on pollen viability and seed development	Elevated UV may reduce seed quality in ways not previously observed in NZ	Field observation; shading trials
Canterbury seed production viability under cooling	If Canterbury becomes too cold for reliable seed production, NZ loses its primary seed multiplication region	Monitor; develop alternative seed production regions (Waikato, Bay of Plenty, Hawke’s Bay)

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CROSS-REFERENCES

• Doc #1 — National Emergency Stockpile Strategy (requisition framework for seed stocks)
• Doc #3 — Food Rationing (seed distribution aligns with food security priorities)
• Doc #8 — Skills and Asset Census (establishes actual seed stocks and seed-saving expertise)
• Doc #74 — Pastoral Farming Under Nuclear Winter (pasture seed requirements)
• Doc #75 — Cropping Under Nuclear Winter (growing conditions and crop selection)
• Doc #78 — Food Preservation (processing of harvested produce)
• Doc #80 — Fertilizer and NZ Phosphate (soil fertility for seed crops)
• Doc #79 — Greenhouse Construction (protected growing for heat-loving seed crops)
• Doc #100 — Harakeke (NZ native plant resource)
• Doc #158 — School Curriculum (seed saving as core educational content)

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1. Seed counts per gram from various seed company data (Kings Seeds catalogue, Yates Growing Guide). Yield figures are approximate for NZ conditions under normal growing. The multiplication ratio is illustrative — actual yields vary enormously with conditions, and would be lower under nuclear winter.↩︎

2. AgResearch, Margot Forde Germplasm Centre information. https://www.agresearch.co.nz/our-research/germplasm-centre/ — The approximately 80,000 accession figure is widely cited; exact current numbers should be confirmed with the Centre. The range 75,000–85,000 reflects uncertainty about whether all documented accessions remain viable. The collection is predominantly temperate grassland and forage species, reflecting NZ’s pastoral research focus.↩︎

3. Seed storage longevity under controlled conditions is well-documented in the seed science literature. See: FAO/IPGRI Genebank Standards (2014) for international standards on base and active collection storage. Under -20°C and <5% seed moisture content, many orthodox seeds remain viable for decades.↩︎

4. Plant & Food Research (formerly Crop & Food Research and HortResearch) maintains germplasm collections across several NZ sites. https://www.plantandfood.com/ — Specific collection sizes and locations should be confirmed directly. Some collections are research-active; others are long-term maintenance.↩︎

5. NZ seed industry structure from industry directories, company websites, and MPI agricultural sector data. Kings Seeds: https://www.kingsseed.co.nz/ ; PGG Wrightson Seeds: https://www.pggwrightsonseeds.com/ ; South Pacific Seeds and others identified through NZ seed industry sources.↩︎

6. This estimate is based on seed industry structure: NZ seed companies typically hold carry-over stock from the previous season plus current-season inventory, representing at least one full planting cycle of normal domestic demand. The actual figure is commercially sensitive. Confirmation would require direct inventory through the skills and asset census (Doc #8).↩︎

7. Canterbury’s dominance in NZ seed production is noted in multiple MPI and industry sources. The 60–70% figure is an estimate based on the concentration of seed production and processing infrastructure in the Canterbury region. Exact figures vary by year and crop type.↩︎

8. Estimate based on Retail NZ data on garden centre numbers and hardware store networks (Mitre 10: ~80 stores; Bunnings: ~50+ stores; plus independent garden centres). Exact count would be established through census.↩︎

9. The proportion of open-pollinated versus hybrid seed in NZ retail and commercial channels is not published in aggregate. The estimates in this document are based on analysis of seed catalogues (Kings Seeds, Yates) and consultation with seed industry sources. These figures are approximate and should be verified through actual inventory.↩︎

10. Farmer-saved cereal seed in NZ is well-established. The Foundation for Arable Research (FAR) provides guidance on seed saving and grain quality. https://www.far.org.nz/ — NZ Plant Variety Rights legislation permits farmers to save seed of PVR-protected varieties for their own use (the “farmer’s privilege”).↩︎

11. Koanga Gardens heritage seed collection. https://kofruitandvegetrees.co.nz/ — Kay Baxter’s work at Koanga Gardens over several decades has assembled one of NZ’s most significant collections of heritage and open-pollinated vegetable varieties adapted to NZ conditions.↩︎

12. This figure is derived from the multiplication ratios in the table above. For example, 1 kg of mixed vegetable seed at an average of 300–500 seeds per gram and yields of 0.3–3 kg per plant produces a wide range of total food output. The “tens of thousands” figure assumes a favourable species mix weighted toward high-multiplication crops (lettuce, tomato, cabbage). Under nuclear winter conditions, actual yields would be lower — probably 30–60% of normal depending on crop and region.↩︎

13. NZ planting calendar from multiple sources including Kings Seeds growing guide, Yates NZ gardening calendar, and NZ Gardener magazine. Regional variation is significant — these dates are approximate for temperate North Island locations.↩︎

14. The 4–8 week seasonal shift is an estimate based on the relationship between temperature and growing-degree-day accumulation for temperate crops. A 5°C reduction in mean temperature delays the accumulation of growing degree days (base 5–10°C depending on crop) by roughly this amount. The range reflects variation between crops with different base temperatures and between NZ regions with different baseline climates. See Doc #75 for detailed analysis of growing conditions under nuclear winter.↩︎

15. The dominance of F1 hybrid cultivars in commercial vegetable seed is a global trend well-documented in the seed industry literature. See: Howard, P.H. (2015), “Intellectual Property and Consolidation in the Seed Industry,” Crop Science. NZ’s market follows the global pattern, with hybrids dominating most commercial vegetable crops.↩︎

16. The proportion of open-pollinated versus hybrid seed in NZ retail and commercial channels is not published in aggregate. The estimates in this document are based on analysis of seed catalogues (Kings Seeds, Yates) and consultation with seed industry sources. These figures are approximate and should be verified through actual inventory.↩︎

17. Yield depression in F2 generations from hybrid parents is well documented in plant breeding literature. The 20–50% yield reduction range is typical for many vegetable crops, though the exact figure varies by species and the degree of heterosis in the F1. See: Allard, R.W. (1999), Principles of Plant Breeding, 2nd edition, Wiley; Simmonds, N.W. and Smartt, J. (1999), Principles of Crop Improvement, 2nd edition, Blackwell Science.↩︎

18. Seed viability data compiled from multiple sources: Harrington, J.F. (1972), “Seed Storage and Longevity,” in Kozlowski, T.T. (ed.), Seed Biology, Vol. III, Academic Press; Justice, O.L. and Bass, L.N. (1978), Principles and Practices of Seed Storage, USDA Agricultural Handbook 506; and practical experience documented by seed saving organizations (Seed Savers Exchange, Heritage Seed Library UK). Actual viability varies significantly with storage conditions.↩︎

19. Harrington’s rules of thumb for seed storage are widely cited in the seed science literature. Harrington, J.F. (1972), as above. The rules are approximations that hold reasonably well within the range of temperatures and moisture contents relevant to practical seed storage but should not be extrapolated beyond this range.↩︎

20. Silica gel absorbs approximately 30–40% of its own weight in moisture; dry rice absorbs roughly 10–15%, and powdered milk approximately 10%. These improvised desiccants require replacement every 1–2 weeks in humid conditions compared to silica gel’s 4–8 weeks (silica gel can also be regenerated by oven-drying at 120°C). Based on standard desiccant comparison data and seed-saving practice guidance from Seed Savers Exchange.↩︎

21. The loss of seed-saving knowledge in developed countries is discussed in: Nazarea, V.D. (2005), Heirloom Seeds and Their Keepers, University of Arizona Press. In NZ specifically, the shift from farmer-saved to commercial seed occurred over approximately 1950–1990 for most vegetable crops. Some farmers (particularly organic and heritage growers) have maintained seed-saving practice.↩︎

22. Isolation distance recommendations from: George, R.A.T. (2009), Vegetable Seed Production, 3rd edition, CABI Publishing; and Seed Savers Exchange guidelines. Distances vary with landscape features, pollinator activity, and the level of genetic purity required. The figures given are minimum recommendations for maintaining varietal integrity.↩︎

23. Tomato seed fermentation technique is standard practice in seed saving. The fermentation process breaks down the gel coat (which contains germination inhibitors) and kills several seed-borne pathogens including bacterial canker (Clavibacter michiganensis). See: George, R.A.T. (2009), as above.↩︎

24. Seed drying temperature thresholds from Justice, O.L. and Bass, L.N. (1978), Principles and Practices of Seed Storage, USDA Agricultural Handbook 506. The 35°C safe maximum is a conservative threshold widely used in seed-saving guidance. Some species tolerate slightly higher temperatures, but the margin of error is small and the consequences of exceeding the threshold are irreversible. The 40–50°C damage range is for seeds at typical post-harvest moisture content (12–20%); fully dried seeds tolerate somewhat higher temperatures.↩︎

25. The development of locally adapted crop populations through farmer selection is documented in extensive literature on participatory plant breeding. See: Ceccarelli, S. and Grando, S. (2007), “Decentralized-participatory plant breeding: an example of demand-driven research,” Euphytica. In NZ, the Heritage Food Crops Research Trust has documented local adaptation in heritage varieties over multiple decades.↩︎

26. Māori kūmara cultivation is extensively documented. See: Furey, L. (2006), “Māori Gardening: An Archaeological Perspective,” Department of Conservation Science Publishing; Yen, D.E. (1961), “The adaptation of kumara by the New Zealand Māori,” Journal of the Polynesian Society. Pre-European Māori developed kūmara cultivation to approximately 38°S latitude — among the most southerly sweet potato cultivation in the world.↩︎

27. Kūmara temperature requirements from Plant & Food Research kūmara growing guides and commercial grower resources. Soil temperature for kūmara planting is typically recommended at 18°C or above. https://www.plantandfood.com/↩︎

28. Roskruge, N. (2007), “Hokia ki te whenua,” PhD thesis, Massey University — documents over 40 named taewa varieties with detailed morphological descriptions. The Tahuri Whenua collective works to maintain and promote taewa cultivation.↩︎

29. Harris, W. and Heenan, P.B. (2004), “Phenotypic variation of Cordyline in New Zealand,” NZ Journal of Botany. Hue (gourd) cultivation by Māori is documented in the ethnobotanical literature; see: Leach, H. (1984), 1000 Years of Gardening in New Zealand, Reed.↩︎

30. NZ school numbers from Ministry of Education. https://www.education.govt.nz/ — NZ has approximately 2,500 schools (primary, intermediate, secondary). Most have grounds that could support garden plots, though urban schools may have limited space.↩︎

31. Seed yield per school garden is an estimate based on typical seed production rates for common open-pollinated vegetables. A single well-managed lettuce plant allowed to bolt produces 5,000–10,000 seeds (~10–15 g); a broad bean plant produces 10–30 seeds. A garden of 50–100 m² devoted to seed production of four species could realistically produce 1–5 kg of mixed seed. The number of home gardens supplied depends on the seed quantity per crop — a gram of lettuce seed supplies many gardens while a larger allocation of bean seed is needed per garden.↩︎