Vegetable Seed Saving: What You Need to Know

Winter squash and pumpkins should be left on the vine until after a light frost. To save seeds, cut the fruit open and scoop out the seeds. Pick out any squash “guts” and dry the seeds on a towel for at least a week (in dry conditions). You can tell these larger seeds are completely dry when you can easily break them in half.

If the squash aren’t quite ripe before a hard freeze, you can cut them off the vine, leaving part of the stem attached, and store them in a cool place for three to six weeks to finish maturing before collecting the seeds.

For summer squash and cucumbers, allow them to ripen past the edible stage because the seeds need to be fully developed. Toward the end of the season you can allow them to stay on the vine until they’re dead before harvesting.

Cucumbers need to be fermented like tomatoes. Follow the same techniques of scooping out the inside and soaking in water for several days. Dry the ones that consistently sink to the bottom on a plate or towel. 

Alternating years

Biennial crops, such as carrots and parsnips, don’t form seeds until the second season, making this a perfect time to plan for next year’s seed collection.

For carrots, cut back the foliage to roughly 1 inch tall and mulch heavily. In the spring, the plants will send up flower stalks. Carrots have perfect flowers, but they need to be pollinated by insects.

The good news is not many home growers save their own carrot seed, making cross-pollination with another garden variety unlikely. Carrots will readily cross with wild Queen Anne’s Lace,  so if it is prevalent in your area you’ll need to isolate the carrot flower heads with a bag or netting and hand pollinate.

Once the seed head dries out, you can shake out the seeds or rub the head between your hands over a plate to collect the seeds. Allow them to dry further for a few days before storing.

As with carrots, leave parsnips in the ground through the winter after trimming back the leaves. Mulch well once again to make sure they survive the cold temperatures. Parsnips will form large seed heads the following year. Once they’re mature, cut them off and hang them upside down to dry with a collection plate underneath.