Saving winter squash seeds
December 5, 2018
I like "Delicata" winter squash. With my most recent purchase, I wondered if I saved seeds, would they produce true "Delicata" squash next fall or some cross-bred anomaly?
Squash are part of the Cucurbit family, which also includes melons, pumpkins and cucumbers. Their monoecious flowering habit is unique among vegetable crops. They produce male and female flowers on the same plant. Pollen must be transferred from a male flower to a female flower of the same species to produce the expected squash variety. Cross-pollination can occur between varieties within a species. There is a garden myth that you can't plant cucumbers next to squash or melons because they will cross-pollinate and taste funny. Even though these plants all have a similar flowering habit, the female flowers of each crop can only be fertilized by pollen from male flowers of the same species. This means that Cucurbita pepo species such as summer squash, pumpkins, gourds and some winter squash can cross with each other but can't cross with muskmelons (Cucumis melo) or cucumbers (Cucumis sativus) since they are different species. In addition, these last two also won't cross with each other or with other Cucurbita species (https://hortnews.extension.iastate.edu/1996/8-23-1996/crosspol.html).
I don't know which variety of "Delicata" I bought, but "Cornell's Bush Delicata" (Cucurbita pepo "Delicata"), bred by Jahn and Moriarty from Cornell University, is not a hybrid, but an open-pollinated variety, so I'm hoping mine is, too. While hybrids might occur naturally through random crosses, commercial seed producers generally control the crosses to allow them to supply exactly the variety farmers want without deviation. These crosses are labeled F1 hybrids. Seeds from F1 plants genetically are unstable and cannot be saved for use in following years, so farmers have to buy seeds for their preferred varieties year after year. Open-pollinated means seeds are pollinated by insects, birds, wind or humans and can be saved. Open-pollinated seeds might be genetically diverse if pollen has been shared between different varieties within the same species. However, if this hasn't happened, the seeds should remain true. To safeguard this, female flowers can be hand-pollinated from the male flowers on the same plant.
To save winter squash seeds, separate them from the pulp by rinsing them in a large mesh strainer. Spread them out on a paper towel or screen and let them dry for a week or so in a warm dry place where rodents can't get them. Then, store them in envelopes or paper bags (not plastic) to avoid moisture retention. Plant next year.
JoAnne Skelly is associate professor and Extension educator, Emerita at University of Nevada Cooperative Extension. She can be reached at firstname.lastname@example.org.