Winter Seed Saving: Pumpkins and Squash

pumkinssmBy Jill Henderson – Show Me Oz

With winter in full swing, the last thing you might be thinking about is gardening. But the two actually go together like pumpkin pie and whipped cream! In fact, if you grew your own pumpkins or squash this year, the holidays are the perfect time for saving seed!

The funny thing about winter squash and pumpkins is that most people think of them as separate vegetables. But the truth is, they belong to a very large family  called the Cucurbit, or Cucurbitaceae, family. Other garden relatives in this large and diverse family also include gourds, summer squash, cucumbers and melons of all types. But unlike their summer cousins, winter squash have relatively dry, sweet flesh that is protected by semi-hard outer skins, or shells, that allow them to be stored for long periods of time.

The first step in saving the seeds of these winter fruits is to understand their botanical connections to one another so they will grow true to type in your garden next year. If you haven’t read my article, Saving Seeds: Open Pollinated vs. Hybrids, now might be a good time to jump over and check it out. It explains in detail how crops cross pollinate and what you need to know to save pure seed.

If you want the short version, here it is: Basically, every plant in the world is classified through a system of nomenclature, which allows us to see how they are, or are not, related. Just like us, all plants belong to a family. Their names can span many generations and include ancestral relationships. Plants are classified in descending order from Kingdom through Variety. For basic seed saving purposes, we need only focus on those names that represent the Family, Genus, Species and Variety.  For example:

Hubbard Squash (Cucurbita maxima “Hubbard”) is broken down this way:
Family – Cucurbitaceae
Genus – Cucurbita
Species – maxima
Variety (or named cultivar) – Hubbard

The more names a plant shares with another plant, the closer they are related. If two plants do not share the same species name, they cannot pollinate one another at all. If they do share the same species name, they will almost always have the potential to pollinate one another. If those same two plants also share the same variety name they have the ability to produce seeds that will bear exact duplicates of one another (i.e. a pure strain) when pollinated by one another.

Cucurbits are a large and diverse family of plants that have a tendency to cross-pollinate. If you save seed that was crossed with a different variety within the same species, the plant that grows from that seed may not be what you expect it to be.  For those new to saving seed, allow me to explain in more detail.

squash flowerssmOnce you know how different plants are related, it is easy to understand how they reproduce, since plants belonging to the same genus use the same process. In the case of Cucurbit species, like winter squash and pumpkins, all have separate male and female flowers on each plant. To complete sexual reproduction, the flowers completely rely on insects to move pollen from the male flower to the female flower. To attract pollinators, Cucurbits often have large, showy flowers with exposed reproductive organs. This method of pollination is very effective, but not necessarily selective. It essentially allows insects to deposit pollen from both related and unrelated species. If the pollen comes from a flower of the same exact species of squash, then the resulting seed will bear the same exact fruit when planted. If not, it’s anyone’s guess what the offspring will look and taste like.

There are four species of Cucurbits that we need to keep an eye on: C. maxima, C. mixta, C. moschata, and C. pepo. In general, you can grow one variety of squash from each of these four species without worrying about cross pollination. The real problem lies in knowing which variety belongs to which species, as that isn’t always obvious. That is why I have included the following list of species and their varieties. Keep in mind that this list is not 100% complete. If in doubt, simply ask the company from which you bought your seed.

  • Cucurbita maxima varieties include banana, buttercup, Hubbard, Hokkaido, kubocha, sweet keeper, red kuri, delicious, French turban, and marrows. All of these varieties will cross pollinate each other, but not those of other species.
  • Cucurbita mixta varieties include all cushaws, many green-and-white striped squash, Japanese pie, silverseed gourd and Tennessee sweet potato. All of these varieties will cross pollinate each other, but not those of other species.
  • Cucurbita moschata varieties include, cheese type squashes and pumpkins, all butternuts, and winter crooknecks. All of these varieties will cross pollinate each other, but not those of other species.
  • Cucurbita pepo varieties include many types of gourds, winter squashes such as acorn, delicata, cocozelle, English marrow, most types of sweet pumpkins and all summer squashes including yellow, crookneck, scallop, spaghetti and zucchini. All of these varieties will cross pollinate each other, but not those of other species.

There are conflicting reports of cross breeding within the different species of the genera, but for the home seed saver, the best method of ensuring purity is to grow only one variety of each of the four species during the growing season. Otherwise, isolate varieties within the same species by up to a mile or hand-pollinate individual flowers.

As previously mentioned, harvesting seeds of winter squash are pretty straightforward. Simply cut open the fruit and scoop out the seeds into a large bowl or bucket. Add a generous amount of water and rub the seeds away from the fleshy membranes. Pour off any floating seeds and chaff, repeating as necessary until the water contains only ripe seeds, which sink in water. Drain the seeds well and dry on a rigid surface such as a ceramic plate (never paper) away from direct sunlight until the seed breaks when folded in half. Store seeds in a dark cool place.

Now that you know how to save the seeds of your home-grown winter favorites like pumpkins and squash, you’ll never have to buy seeds of that variety ever again! Enjoy!

Learn more about saving seeds with my book
The Garden Seed Saving Guide

Whether you’re a weekend gardener, homesteader, or serious survivalist, saving seeds is a money saving skill that every green-thumb should to have. An excellent resource for beginners and experienced gardeners alike, The Garden Seed Saving Guide takes you step-by-step through every aspect of saving seeds. If you want to save money, become more self-sufficient and avoid genetically modified food crops, The Garden Seed Saving Guide is for you.  Available from Groundswell Books at Amazon

Feel free to share with a link back to this site!  Thanks.

Jill Henderson is an artist, author, and the editor of Show Me Oz . Her books, The Healing Power of Kitchen Herbs, The Garden Seed Saving Guide and A Journey of Seasons can be found in the Show Me Oz Bookstore. Jill’s work has also appeared in The Permaculture Activist, The Essential Herbal, Acres USA, and Llewellyn’s Herbal Almanac.

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13 responses to “Winter Seed Saving: Pumpkins and Squash

  1. Saving seeds has become one of my favorite new pastimes. It takes planning, but with gardening, planning is the most fun part, especially during the dark winter.
    When it comes to Cucurbita, I am establishing a 4 year schedule. I plant some varieties from only the 4 species that you mentioned above, thus ensuring that what I plant stays true to the parent. The next year I plant different varieties of the same 4 species. When the 4 years are up, I plant the seeds that I saved from the 1st year and so on… When it is all said and done, I will have 16 varieties of Cucurbita saved up. When stored properly, the seeds will remain viable for 6 or more years. I give most of my seeds to my friends and neighbors.
    If I had more time, I would attempt hand-pollination, but alas, it is not to be.
    As a bonus, pumpkin seeds are edible, and are very tasty when salted and roasted. My kids love them.

    I enjoy reading all of your articles.

    • Thanks for your comment cbarru, I’m glad you’ve enjoyed the articles. Your cucurbit rotation plan is an excellent one – thank you for sharing it. Not only do you have an abundance of seed to replant and to share, but you also have the pleasure of enjoying many different cucurbits throughout the years!

      I am like you in that I don’t find hand pollination an efficient use of limited gardening time, though if pressed, one could hand pollinate only a few flowers and still come away with a ton of seed! Thanks again!

  2. Another great article. Thanks, Jill.

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  4. Thanks for the tips, Jill! I wrote an article about pumpkins for Missouri Life magazine (, and was delighted to learn about their natural history! Baker Creek Heirloom seeds contracts with gardeners to grow different pumpkins in just the method you described.

    On site though, they also plant different cultivars in hoop houses covered with a biodegradable material. To pollinate, bumblebees from Europe come in boxes with nesting material, a food source, and holes for oxygen. Those boxes get attached at the very end of the hoop house so they can come back to nest but stay contained to that cultivar. Once pollination’s over, the bees are set free! Fascinating stuff.

    This is my first year as a grown-up with a yard, so I’m excited to save seeds from a big Cushaw that’s chilling on my porch. It came from Hartsburg, where all kinds of pumpkins run rampant, so the seeds might produce some hybrids. But that’s part of the fun, right?

    • Thank you, Tina. I’m so glad you enjoyed it. We love to grow squash in our garden, but we’ll never get anywhere near the 140 varieties Kate Kammler grows! Wow, that’s a lot of squash (and pumpkins)!! I’ve heard of people bringing bees into greenhouses, but I never really knew how they did it. Very cool. And you’re right about cross pollination creating hybrids. But if you are excited by the possibility of the outcome, then you might also like to learn to breed your own stable variety. I suggest the book, Breed Your Own Vegetable Varieties, by Carol Deppe. If nothing else, it’s an incredibly interesting read! 🙂

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