Seed Saving

Saving seed means you never run out of a variety you love, you stop paying for packets, and over the years your seed adapts to your own garden. Most of it is simple. The skill lies in knowing which plants come true and which ones cross.

Start with the right plants

• Open-pollinated varieties grow seed that comes up like the parent (“true to type”) ¹.
• Heirlooms are open-pollinated varieties passed down for generations for a quality like flavor, color, or hardiness ¹.
• Hybrids, labeled F1, are a deliberate cross of two parents. Their seed usually doesn’t resemble the parent, and some is sterile. For those you buy new seed each year ¹.

The easiest crops to start with are peas, beans, lettuce, and tomatoes. They’re annuals that mostly pollinate themselves, need little isolation, and need only a few plants to save good seed ¹.

What crosses with what

The common belief is that anything in the same family crosses: cucumbers with squash, or squash with watermelon. It’s false. Different species don’t cross. Varieties of the same species do: a zucchini and a pumpkin, for example, which are both Cucurbita varieties ¹. The fruit you eat this year looks normal either way; the cross only shows up next year, when you plant the seed.

That’s why distance matters. Crops differ in how far their pollen travels ¹:

If you can’t get that far apart, use one of the other two methods ¹:

• Time: stagger plantings so the varieties don’t flower together.
• Containment: cover flowers or whole plants with paper or mesh bags or row cover, then hand-pollinate: dab pollen from a male flower onto the female flower’s stigma with a small brush, or rub the male flower right onto it.

Carrots, beets, cabbage, kale, and onions are biennials: they flower and set seed in their second year ¹, so in Wisconsin they have to be overwintered in the ground under mulch or dug, stored, and replanted in spring.

Dry seed

Beans, peas, onions, carrots, corn, flowers, and herbs: let the seed mature and dry on the plant. Cut seed heads just before they’re fully dry if they shatter easily, then finish drying them in a single layer on a screen in a cool, airy place, or in a paper bag that catches the seed ¹.

Wet seed

Tomatoes, cucumbers, and melons hold their seed in wet pulp with a gel coating ¹:

1. Pick a fully ripe fruit (cucumbers for seed go well past eating stage, to yellow and soft).
2. Scoop the seeds and pulp into a jar with a little water.
3. Let it ferment 2 to 4 days, stirring daily. The fermentation breaks down the gel coat.
4. Good seed sinks; pulp and dead seed float. Pour off the top, rinse, and repeat until the seed is clean.
5. Spread the seed on a screen or paper towel to dry completely.

Storing

Keep seed cool and dry. Paper envelopes inside a glass jar keep out moisture and pests. Label every envelope with the crop, variety, and year ¹.

Try it

This fall, save seed from one open-pollinated tomato and one bean variety: ferment the tomato seed and let the bean pods dry on the vine. Next spring, plant some of each and compare them with the parents. If they come true, you’ve started your own seed line.