With so many questionable seed sources these days, I think it’s a good idea to experiment with seed saving in our gardens. Doing so allows us to maintain a continuous supply of heirloom seeds for our own use, plus we can share or trade the seeds with others, keeping these plants in cultivation.
I’ve had good luck saving seeds from veggies like basil, daikon, lettuce, pumpkin, and radish, as well as flower seeds like zinnia, marigold, and nasturtium. The technique varies a bit from veggie to veggie, but allowing one or two plants to go to seed is a good idea if you’d like to save some money on seeds and continue to have a steady source of seeds to plant.
What does that mean, though, letting veggies go to seed?
It means that you’re allowing some plants to complete its life cycle rather than harvesting before it has a chance to do so. A vegetable plant’s sole purpose is to regenerate. Most of them do so by creating seed to perpetuate the life cycle, but we often harvest vegetables before they have a chance go to seed. Of course, plants like tomatoes, pumpkins, and peppers have visible seeds inside the fruit; for these, it’s not necessary to let them “go to seed.”
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Saving seeds from your garden
If you’re interested in saving seeds from some of your garden plants, note that heirloom seeds or open-pollinated seeds will “come true” from year to year. In other words, you’ll end up with a plant with the same characteristics from year to year.
This is not true with hybrid seeds. Hybrid seeds may very well sprout, but certain qualities that may have been valuable in the first generation might be lost in subsequent generations.
With plants like tomatoes and peppers, the seeds are visible inside the fruit, the part that we eat. But other vegetables — lettuce, kale, and carrots, for instance — are grown for their leaves or roots. As we harvest the leaves to use in salads, we don’t see seeds. Instead of pulling that radish or lettuce plant for lunch, leave it in the ground and allow it to flower. For root crops and greens, the flowers are typically followed by pods.
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Note that often times when fruit is left on the vine to complete its life cycle, it may appear in your garden next spring as a volunteer. Tomatillos and tomatoes are notorious for popping up in my spring garden, unbidden. I embrace this, and often the volunteer plants that pop up are healthier than any that I cultivate. This “method” leaves a lot of room for error — for one thing, you’ll never know what variety has self-sown. Which is why many gardeners like to save seed and plant it themselves.
If you are intent on saving seeds from your garden to replant a favorite variety, be mindful that many crops can be cross-pollinated by wind or pollinators like bees and butterflies. While you might not see it in the current crop, the seeds that develop in a cross-pollinated plant may have unexpected features when you grow them next year. For instance, a gourd plant that cross-pollinates with a nearby pumpkin may net a bumpy pumpkin next season. To avoid cross pollination of different varieties, plant them at some distance. Serious seed savers sometimes call for a distance of a half mile!
How to save seeds from brassica plants
Also known as cruciferous vegetables, crops such as cabbage, broccoli, cauliflower, and mustard all produce seeds in a similar manner. When left in the ground to mature, these plants will send up a flowering stalk. (At this point, it’s a good idea to stop harvesting leaves from the plant as they’ll likely be bitter.) Each of the flowers on that stalk will turn into a seed pod over the course of a couple of months. Left to its own devices, the seeds will drop and scatter, often popping up in the garden the next spring.
To save seeds for replanting next year, wait until the seed pods get fat and look like they’re starting to dry out. You can harvest individual pods, or pull the plant and let the seed pods thoroughly dry on the plant. I like to hang plants upside down in a covered area that’s cool and dry.
Note: Some brassica crops are biennial; see below for more on saving seeds from these vegetables.
Once the pods are thoroughly dried out, break them open to reveal the next generation of seeds. Remove those seeds and store in an airtight container until the following planting season.
How to save pumpkin seeds
Unlike summer squash, pumpkins and other winter squash (such as spaghetti squash and butternut squash) are generally harvested at full maturity, when their color begins to change and the stems dry out. Once harvested, allow pumpkins to sit for at least 20-30 days before opening for seed saving purposes. With these veggies, it makes sense to simply save the seeds when you’re cooking one — you don’t have to forfeit it as you do with some other vegetables.
Cut the squash in half and scoop out the seeds and pulp. Place the pulp and seeds in a colander and rinse under cold water to remove the pulp. If you find that the pulp is difficult to remove, you can soak the seeds in a bowl of cold water for several hours to help break up the pulp. Set rinsed seeds on a kitchen towel to dry, then transfer to a piece of newspaper. Place seeds somewhere with good airflow and out of direct sunlight. When thoroughly dry (seeds should snap in two when bent), store in an airtight container in a cool, dark place.
Saving squash and cucumber seeds
Summer squash and cucumbers both have visible seeds in them upon harvest. But you’ll note that they’re small — those seeds are still immature. In order to save squash seeds or cucumber seeds, you’ll need to let the fruit grow to full maturity. Do this with a plant that’s nearing the end of its productivity. Both squash and cucumber will fill out and start to yellow (or even turn orangish) as they mature. As long as weather allows, you can leave the plants on the vine, giving them about two weeks or so after the color change.
When the fruits begin to soften, cut them in half and scoop out the pulp and seeds.
For summer squash and zucchini seeds: Place the seeds in a bowl of water and swish to remove pulp. Transfer rinsed squash seeds to a towel to dry, then put them on a sheet of newspaper somewhere with good airflow and out of direct sunlight. When thoroughly dry (seeds should snap in two when bent), store in an airtight container in a cool, dark place.
For cucumber seeds: To successfully save cucumber seeds, ferment them. This process makes it easy to remove the seeds from the pulp. Place the scooped pulp and seeds — along with a bit of water to thin the mixture out — into an uncovered jar. Keep jar at a temperature of 70-80ºF for 1 to 3 days. After fermentation, add more water to the jar and swish. The pulp will rise to the surface for easy removal, while the seeds sink. Transfer rinsed seeds to a towel to dry, somewhere with good airflow and out of direct sunlight. Store in an airtight container in a cool, dark place. [More on growing cucumbers here.]
How to save pepper seeds
If you’ve sliced open a bell pepper or hot pepper, you’re familiar with their seeds. To harvest viable seeds, allow the peppers to mature fully on the plant, to the point of softening. Cut the pepper open, either by cutting in half or removing the stem crown. Use the tip of a knife to scrape out the seeds. Transfer seeds to a dry towel or a sheet of newspaper and allow to dry for several days. Test their dryness by bending; a dry pepper seed should snap in half. Store in an airtight container in a cool, dark place. [More on growing peppers here.]
Use caution when saving hot pepper seeds, as the inner membranes around the seeds contain capsaicin which can burn.
Saving pea seeds and bean seeds
These are probably the most obvious seeds we can harvest from our garden.Think about peas and green beans. Shelling peas have fully formed peas — seeds — inside. Green beans are most tender when harvested young, but left to mature, those green beans will produce seeds. Those seeds will look suspiciously like the green bean seeds you planted. For all peas and beans, allow the pods to reach maturity. This means that you’ll allow green beans or snap peas to get much larger than you would if you were harvesting them to eat in the pod. If the weather allows, let pods yellow and dry on the vine. If rain threatens, harvest the pods and allow them to dry thoroughly. Once dried, open the pods and remove the peas or beans. Store in an airtight container in a cool, dark place. [More on growing beans here.]
How to save tomato seeds
As mentioned above, tomatoes have a tendency to self-sow in the springtime. Fruit that drops rots on the ground, resulting in the breakdown of the gel-like coating on the seeds over the course of the winter. To hurry up that process, gardeners can ferment the seeds and pulp, which allows easy removal of that coating. Choose your favorite tomato variety and cut a fully ripe fruit in half horizontally. This exposes the seeds. Squeeze the seeds and pulp into a jar. (Reserve the remaining squished tomato for cooking.)
Set uncovered jar in an out-of-the-way spot for 3-4 days. As the pulp ferments, it may develop a bit of mold on the top; this is okay. The fermentation process will cause the seeds and pulp to separate. When you see this happening, stir some water into the jar. Mature, viable tomato seeds will sink. Pour off most of the liquid and pulpy matter. Strain the remain seeds through a sieve. Rinse thoroughly under running water; drain. Spread tomato seeds on a kitchen towel to dry. Once thoroughly dry (a bent seed will crack in half), carefully remove the seeds from the towel and store in an airtight container in a cool, dark place. [More on growing tomatoes here.]
Saving basil seeds
Basil is a garden favorite and it’s easy to save seed from year to year. Choose one basil plant as your seed producer. Let it flower and watch as those flower heads turn to seeds. Allow the seed to brown on the plant. If wet weather threatens, you’ll want to clip them and bring them inside to dry. Pull the dry seed pods from the stem. Roll dry pods around in the palm of your hand to remove the small black seeds. Seal fully dried basil seeds in a paper envelope or jar and store in a cool, dry place. [More on growing basil here.]
All of the crops I’ve addressed above are annuals, meaning that they complete their life cycle in one season. A biennial crop needs two seasons in which to complete its life cycle. These crops include some brassicas (kale and cauliflower are two), celery, carrots, beets, and Swiss chard. In cold climates, this requires gardeners to dig up these crops and overwinter them inside. They’ll be in a dormant state during the cold months. When spring arrives, you’ll plant them in the garden again with the sole intention of harvesting their seeds.
This is a bit more work than many gardeners are willing to tackle, but for avid seeds savers it could be a fun project to tackle.
Store seeds properly
Once you’ve gathered and dried seeds from your garden, you’ll need to store them so they remain viable. Package them in recycled junk mail envelopes or put them in a glass jar with a desiccant packet to keep moisture at bay. Store saved seeds in a cool, dry place until it’s time to plant again next season.
Have you done any seed saving? What have you had the most luck with?
Originally published May 2011; this post has been updated.