How to save squash seeds

Wondering how to save squash seeds? These yummy vegetables are great candidates for beginner seed saving!

To save squash seeds, start by pollinating blossoms by hand to avoid cross-pollination. Collect ripe hand-pollinated squash from 6-12 (or more) plants of one variety. Slice into each squash and remove the seeds with a clean spoon. Wash the seeds with clean water and discard any seeds that float. Place the seeds out to dry for a day or two until they are crisp. Label and store in an airtight container.

Read on to learn all about how to save squash seeds!

How to save squash seeds
Seeds from ‘Long Island Cheese Squash’ (Cucurbita moschata)

Introduction to saving squash seeds

Squash seeds are one of the simplest seeds for novices to preserve for future planting. Unlike many other vegetables, squash plants are not self-pollinating. They require assistance from bees or other insects to spread pollen from the male flowers to the female flowers. Each flower only blooms for one day, so timing is crucial if you want to save seeds from your own squash plants.

If you’re growing more than one variety of squash (or your neighbors are growing squash), it’s important to hand-pollinate the flowers to avoid cross-pollination. Cross-pollination will result in squash plants that are not true to type and may produce fruit that is less desirable. To hand-pollinate, transfer pollen from the male flower of one plant to the female flower of another plant.

Planting squash for seed saving

Plant a minimum of six to twelve squash plants of the variety you’d like to save in the fall. This will ensure you have a large quantity of viable seed that is genetically diverse.

Squash plants are not self-fertile. Each plant grows both female and male blooms, but the female flowers must be fertilized with pollen from a male flower on a different plant in order to produce good-quality fruit and seeds.

Use two plants of the same variety to pollinate each other. A single plant pollinating itself won’t lead to good seeds. To avoid accidentally pollinating a plant with its own pollen, space the squash seeds out enough so it’s clear which vines belong to which plants.

Choose an open-pollinated variety

Make sure the squash you select is open-pollinated. Seeds saved from hybrids (F1 crosses) will not save true to type. It’s also good to note the species of squash (most are Cucurbita pepo, Cucurbita moschata, or Cucurbita maxima).

Here are some great open-pollinated squashes:

Isolation between varieties of squash

Squashes of the same species but different varieties should be kept separate. So, if growing both dark green zucchini and sugar pie pumpkin, which are both Cucurbita pepo species cultivars (even though zucchini is considered a summer squash and pumpkins are considered a winter squash), you’ll have to take care to isolate blossoms for true-to-type seed saving. The distance between your squash varieties will help keep them separate from pollinators, as well as any physical dividers that you create.

Squash plants have large isolation distances for seed saving. Isolate varieties of the same species by at least 800 feet (250 meters). Because this is such a large distance, it makes more sense to isolate and hand-pollinate individual blossoms rather than the entire patch.

To save squash seeds, either bag individual flower buds before they open or hold them closed to prevent insects from entering. You may either seal them shut with tape or keep them closed with a clothespin or hair clip. If you have an entire hoop house with insect netting, that’s even better (as long as you keep it to a single squash variety inside for true-to-type seeds).

Companion planting for seed saving

Many seed savers like to add a variety of flowers to the garden. These blossoms are intended to keep pollinating insects engaged and distracted. Instead of moving from plant to plant, we want bumblebees to spend their time around these other flowers instead of traveling between squash plants. Planting a tall crop like corn between varieties will also decrease cross-pollination.

Growing squash for seed saving

Grow healthy squash plants by watering them often, removing any sick leaves, and examining for pests. Apply a slow-release organic fertilizer and mulch the ground surrounding the roots to keep them cool and wet.

Isolating blossoms for pollination

Watch for emerging squash blossom buds to catch them before they open. The tips are generally greenish-yellow, and are still straight and pointed rather than rippled at the end.

Before the flower buds open, place a mesh or silk bag over them to protect them from dust. Alternatively, tape or a clothespin/hair clip the petals shut to keep insects out and allow for gentle hand pollination with a paintbrush or flower-to-flower.

Hand pollinating squash blossoms

Pollinate squash blossoms early the next morning. Blossoms close in the afternoon and flower pollination tends to be less successful at very hot temperatures.

Find a female flower on each plant to be pollinated. It should still be held closed but should look like it wants to open. Each flower to be pollinated will need to have pollen from a male flower from a different plant brought to it (of the same variety if trying to save true-to-type).

To identify which squashes are hand-pollinated, tie a label or a ribbon onto the stem below the blossom before pollinating. Remove the petals from the male flower and open the female flower. Tap the exposed anthers onto the stigma of the female flower. You can also use a small paintbrush to apply the pollen if that’s easier.

Care after pollinating

Once pollination is complete, pull closed the petals on the female flower and bag it or clip it shut again. Repeat this process for each taped/clipped blossom on each plant. Each one should get its own label and bag or clip so you can keep track of which was pollinated.

After pollination, the flowers will wilt and die back. The fruits will mature and ripen as normal. Thin large squash like Hubbard back to 1-2 squash per plant. Medium-sized squash like kabocha can be thinned to 3-4 per plant. Allow them to stay on the vine until completely ripe before harvest.

Choosing squash to save seeds from

Squash should be left on the vine to ripen. They should have a very firm rind that cannot be pushed with your fingernail. The stem must be dry and rigid.

Harvest the hand-pollinated pumpkins that were intended for seed saving. To achieve genetic diversity, you’ll need at least 6 pumpkins. Save seeds from distinct individuals or plants only if they appear to be healthy and disease-free.

Cure the pumpkin by leaving it in a warm place for a few weeks. Many winter squash seeds like Cucurbita maxima and Cucurbita moschata should then be stored whole for a month or two prior to harvesting the seeds.

How to save squash seeds?

To save the seeds, cut the squash open and scoop out the pulp and seeds from the seed cavity into a bowl. Separate the seeds from the stringy pulp and rinse them well with clean water. The viable seeds tend to sink to the bottom of the bowl while seeds that float on top of the water are usually discarded to the compost pile.

Spread them out to dry on a plate, cookie sheet, coffee filter, paper towel, waxed paper, window screen, baking sheet, or in a fine-mesh strainer. They should be in a single layer, and hopefully, spaced out from one another. A minimum air temperature of 72°F will help speed up the drying process. Avoid using a dehydrator or oven since the intense heat might damage the seeds.

When they’re completely dry, seal the dry seeds in a glass jar with a good lid or an airtight plastic container and keep them in the fridge or freezer. You may want to store the seeds inside the jar (or lots of jars if you’re saving from multiple pumpkin varieties) within a larger airtight container for extra protection.

Saved squash seeds should last for 5 years if stored properly. To test if they’re still viable, plant 5-10 seeds in a moist potting mix and keep them warm (70-80°F is ideal). The germination rate should be at least 70%.

Mary Jane Duford
Mary Jane Duford

Mary Jane Duford is a passionate gardener and well-acclaimed authority in the world of horticulture. As a certified Master Gardener and Permaculture Garden Designer with over a decade of hands-on experience, she has honed her skills to cultivate a deeper understanding of the natural world around us. Beyond her gardening prowess, Mary Jane holds a distinct edge as a Professional Engineer, an expertise that often intertwines with her gardening methodologies, bringing a unique perspective to her readers.

She is the proud founder of the renowned gardening website, Home for the Harvest, a platform dedicated to helping fellow gardeners, both novice and experienced, find their green thumbs. Her gardening expertise hasn't gone unnoticed; she's been spotlighted as a go-to gardening expert by notable publications like Better Homes & Gardens, Good Housekeeping, Mother Earth News, Real Simple, and the National Garden Bureau.

Delving deep into specific fields of study within horticulture, Mary Jane has an extensive knowledge base on sustainable gardening practices (including permaculture), soil science, and selecting cultivars well-suited to home gardeners. Her passion isn't just limited to plants; she's a staunch advocate for holistic, eco-friendly gardening techniques that benefit both flora and fauna.

Currently residing in the picturesque Okanagan Valley, Mary Jane cherishes the time she spends with her family amidst nature, always exploring, learning, and growing both as a gardener and as an individual.

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