Seed Saving Made Simple Part II – Summer Squash, Winter Squash and Cucumbers

With the arrival of cooler September weather and shorter days, the harvest of both produce and seeds is now well under way for home gardeners in our area. This week, Cathy Christie from the Kingston Area Seed System Initiative (KASSI), continued her discussion of open-pollinated seed saving, focusing on members of the Cucurbitaceae or gourd family including squashes and cucumbers.


Cucumbers, Cucumis sativus are among the easiest of seeds to save. Did you know that we eat cucumbers when they are immature? To save seeds, allow the fruit to mature on the vine, growing large and turning yellow or orange (depending on the variety). To some, these large and over ripe cucumbers are a missed opportunity for a salad, but Cathy sees this end of season bounty as a chance to save seeds!

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To do so, simply cut the cucumber in half lengthwise, scoop the seeds into a bowl and compost the remaining flesh or add them to your sauerkraut. According to some sources the seeds and their protective gelatinous outer coating should ferment for a day or two.  You can use a whisk to gently help dislodge the outer coating.  Cathy suggests that you watch them closely so that they don’t sprout.  After fermentation simply add fresh water, stir and decant the liquid along with any immature seeds that float to the top. Repeat as needed and then dry the seeds on a screen or wax paper. When fully dry, store in a labelled glass container.

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Classification of Squash

Plants in the squash family have been grown for thousands of years, most domesticated from species originating in South America. 

We generally divide the squashes into either winter or summer types. Summer squash (e.g. zucchini) have relatively thin skins and soft flesh and seeds. They are eaten right after harvest as they do not store well.  Winter squash (e.g. butternuts, pumpkins) have thicker rinds, hard seeds and are harvested at the end of the season, cured and stored for the months ahead.

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Taxonomically, squashes are in the genus Cucurbita. There are four cultivated species, three of which we grow most often as a food crop: Cucurbita maxima, C. moschata and C. pepo.  Within each of these are many different varieties. All bear large yellow blooms with both male and female flowers occurring on the same plant. They are insect pollinated and if you were watching closely over the summer months, you no doubt noticed the native squash bee cruising among the flowers in your patch. 

  • C. maxima – mostly winter squashes including Hubbard, buttercups, turban and banana, as well as mammoth pumpkin. Soft round stems that turn corky when mature
  • C. moshchata – Canada crookneck, recent butternut cultivars such as the popular Waltham butternut, cheese pumpkins. Tan, buff or pale orange rind
  • C. pepo – includes both summer squash (zucchini, patty pan) and winter types (acorn, spaghetti, pie pumpkins, decorative gourds)


While these three different species (C.maxima,  C. moschata and C, pepo) are generally not cross compatible, squashes will cross pollinate with others of the same species, and so if seed saving is intended, each must be isolated from others. Isolation distances are long – up to 1500 metres, which is not always practical for a city gardener! Alternatively, they can be hand-pollinated to ensure the resulting seeds will be like the parent plant.  If cross pollination has occurred, the next generation will be an entirely new (and potentially tasty) variety.

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To hand pollinate a squash and thus ensure true-to-type seeds, simply brush some pollen taken from the male flower onto the stigma of the female flower. Wrap the flower tightly and secure it

Saving Squash Seeds

For winter squash types, seeds are typically mature when fruits are normally harvested for eating. After harvest, they benefit from a period of post-harvest ripening or curing in a cool dry location off the vine before being placed in long-term storage. This allows the seeds to mature.  Interestingly most  winter squash become sweeter the longer they are stored.   . When ready to eat, cut it lengthwise, gently to avoid damaging the seeds. Scoop the seeds out and remove as much pulp as  possible by hand.  Rinse and then dry completely on a screen or wax paper. Store in a labelled glass jar. And of course, enjoy the flesh for dinner!

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To save seeds from summer squash such as zucchini, allow a few to grow large and slightly over-ripe, and then process as described above for cucumbers.


Cathy’s favourite resources for more information about seed saving are:

Lee Buttala and Shanyn Siegel, eds. The Seed Garden; The Art and Practice of Seed Saving. Decorah IA, Seed Savers Exchange Inc., 2015.

Seed Savers Exchange

Seeds of Diversity Canada