Survival gardening: calories from stored seed

What a garden can and cannot do for you

A garden is the second season of a plan, not the first week of one. Seed planted today is food in two to four months if the weather cooperates, and the pantry has to carry you until then. Anyone who tells you a seed tin in the closet is a food supply is skipping the part where you learn to grow it.

That is the honest case for starting now, while nothing is wrong. Gardening is a skill with a one-year feedback loop: you get one try per season to learn your soil, your pests, and your frost dates. A small bed you have grown for two summers is worth more than a vault of seed you have never opened.

Four crops that carry the calories

Lettuce and tomatoes are wonderful and they will not feed you. If the goal is calories, four crops do most of the work: potatoes, dry beans, winter squash, and corn. The numbers below are from USDA FoodData Central, per 100 grams, with our arithmetic per pound.

Read the table for the pattern, not the decimals. Dry beans and dry field corn are dense because the water is gone, which is also why they store so well. Potatoes and squash are mostly water, heavy per calorie, and still worth growing because they yield a lot from a small space. For scale: a 2,000-calorie day is about 5.7 pounds of potatoes, or about 1.3 pounds of dry beans.

• USDA FoodData Central (search any crop by name)

Zones and frost dates are two different maps

Most people start with the USDA Plant Hardiness Zone Map, and it is the wrong map for this job. USDA builds it from the average annual extreme minimum winter temperature, and it exists to tell you which perennials will survive your winter. Beans, squash, and corn do not survive any winter. They live and die inside one frost-free season.

The map that matters for these four is your frost dates. NOAA publishes the average date of the last spring freeze and the first fall freeze, meaning the last and first nights at 32°F or below, from the 1991 to 2020 climate normals. The days between those two dates are your growing season.

Every seed packet lists days to maturity. Compare that number to your season and you know whether a variety can finish where you live. Beans, squash, and corn are frost-tender, so they go in after the last freeze. Potatoes tolerate cool soil better and are usually planted earlier. Averages are averages: NOAA says plainly that any given year can differ widely, so leave yourself a margin at both ends.

• USDA Plant Hardiness Zone Map (USDA ARS)
• NOAA NCEI: when to expect your last spring freeze
• NOAA NCEI: when to expect the first fall freeze

Starting from stored seed

Stored seed loses vigor with age, heat, and moisture, and you will not know how much until something fails to come up. Test before the season, not during it: roll ten seeds from a packet in a damp paper towel, keep it in a bag somewhere warm, and count what sprouts over the next week or so. Seven of ten means plant a little thicker. Two of ten means buy fresh seed while you still can.

Know what kind of seed you stored. Hybrid seed is bred for one generation of strong, uniform plants. USDA's Economic Research Service notes that crops grown from seed saved off a hybrid crop are typically less vigorous and yield significantly less. If you plan to save seed, and you should, start with open-pollinated varieties, which grow true when saved.

Potatoes are the exception to all of this. You plant a piece of potato, not a seed. Garden suppliers sell seed potatoes grown for planting. Grocery potatoes are grown to be eaten and are often treated to slow sprouting, which is exactly what you do not want in the ground.

• Start small. A ten-by-ten bed you actually tend beats a quarter acre you abandon in July.
• Pick the sunniest ground you have. All four of these crops want full sun.
• Plan for water. A garden in a dry month drinks from the same supply your household does.
• Your county extension office publishes the local planting calendar and can test your soil. It is the best local source you have.

• USDA ERS: The Science of Seed (PDF)
• USDA National Agricultural Library: seeds and plants

Harvesting the four

Each of these crops tells you when it is ready, and for the storage crops the rule is the same: let the plant finish the drying for you.

• Potatoes: when the tops yellow and die back, the tubers are done growing. Dig on a dry day with a garden fork, taking care not to spear the tubers, and let the skins toughen somewhere dark and well ventilated before storing. Cut or damaged potatoes get sorted out and eaten first.
• Dry beans: leave the pods on the plant until they are dry and papery and the beans rattle inside. Pick when the pods and the beans inside are completely dry, then shell them by hand or in a sack.
• Winter squash: harvest when the rind is hard and a fingernail will not dent it, and before a hard frost. Leave a few inches of stem on. A squash without its stem rots from the top.
• Sweet corn: pick when the silks are brown and a kernel pressed with a thumbnail gives milky juice. It is at its best that day and fades fast.
• Dry field corn: leave the ears on the stalk until the husks are brown and the kernels are hard, then finish drying under cover.

Seed saving: closing the loop

Seed saving is what turns a garden from a purchase into a supply. It is also the part most guides skip. The crops differ a lot in how easy they make it.

• Beans are the easiest. Their flowers mostly pollinate themselves, so beans saved from an open-pollinated variety come back true. Save from your healthiest plants, from the dry pods you would have harvested anyway.
• Squash crosses freely. Insects carry pollen between squash of the same species, so two varieties grown side by side can give you odd fruit next year. Grow one variety per species if you want to save seed. Scoop seed from a fully mature fruit, rinse it, and dry it well.
• Corn is wind-pollinated and crosses with any corn nearby, including a neighbor's. It also loses vigor when saved from too few plants, so save from many ears across the patch, not your single best one.
• Potatoes are saved as tubers. Set aside firm, healthy, medium potatoes as next year's seed potatoes, and never replant from plants that looked sick.
• Dry every saved seed thoroughly, then store it cool, dark, and dry in a sealed jar. Label each one with the variety and the year. Unlabeled seed is a guess.

Storage that needs no preservation

Three of the four store without any processing at all, which is a large part of why they are on this list. Fully dried beans and dried field corn keep a long time in sealed containers kept dry and away from pests. Cured potatoes and winter squash keep well somewhere cool, dark, and dry, and each has its own preferred conditions. Check them weekly and pull anything soft before it spoils the rest.

Everything beyond that is preservation, and preservation is where this page stops.

What it all weighs

The seed weighs almost nothing. A season's worth for a family garden fits in a shoebox. The harvest is the heavy part, and the arithmetic is humbling. At about 1,510 calories a pound, one adult eating nothing but dry beans at 2,000 calories a day would need roughly 480 pounds of them for a year. Nobody grows that in a backyard bed.

That is the right way to think about a garden: it stretches a pantry and it teaches you a skill. It does not replace the pantry, least of all in the first year.

• Seed: ounces. Store it cool and dry and test it every spring.
• Tools: a spade, a digging fork, a hoe, gloves, and a way to carry water. Nothing exotic.
• Time: the real cost. Plan on regular hours every week from planting to harvest.
• Water: often the limit. In a dry spell the garden competes with the household for the same supply.

Bridge to the first harvest

A garden starts paying months after you plant it, so the first month has to be covered by what is already in the house. Our guide to staying put for the first month covers that pantry, the water, and the power, and the kit builder can assemble the gear for it against a budget.

• Staying put: the first month