Saving Squash Seeds for Next Year’s Garden: 7 Pro Tips

Did you grow the biggest pumpkin of your gardening career this year? Were your delicata squash particularly beautiful? Are you just looking to spend less money on seeds next year? There are many reasons why you may want to save squash seeds for next year’s garden. The process is simple and rewarding. Plant biologist Emily Estep will walk you through the steps and provide 7 pro tips.

A close up shot of an orange vegetable crop cut in half that is one process of how to save squash seeds

Contents

Many gardeners enjoy saving seeds at the end of the growing season so they can create free home-grown packets to grow again in spring. Over time, you can cultivate your own heirloom varieties and share them with friends and family. These local heirlooms are usually well-suited to your environment and thrive with minimal effort.

This is particularly fun to do with squash. Whether it’s a butternut or a pumpkin, sometimes you’re just really proud of a certain gourd and want to grow it again. Re-growing from these fruits can create a lineage of plants that thrive in your garden. It may just become your autumn tradition.

While a lot of perennial flowers make it super easy to save their DNA—often it’s as easy as cutting off the spent flower head, putting it in a paper bag, and shaking it up—the process of saving squash seeds is a bit more complicated.

Whether you’ve been saving pumpkin seeds for years, or you just have a particularly stellar squash you’d like to replicate and want to try this procedure out for the first time, we’ve gathered a list of pro tips to help you through the entire process.

Waltham Butternut Winter Squash

Waltham Butternut Winter Squash Seeds

Our Rating

Waltham Butternut Winter Squash Seeds

Vegetable Spaghetti Winter Squash

Vegetable Spaghetti Winter Squash Seeds

Our Rating

Vegetable Spaghetti Winter Squash Seeds

Honey Boat Winter Delicata Squash

Honey Boat Winter Delicata Squash

Our Rating

Honey Boat Winter Delicata Squash Seeds

Don’t Waste Time With Hybrids

A close up shot of various hybrid vegetable crops with various patterns and colors ranging from orange, white, and green.
Hybrid varieties will produce fruits that are not true to its parent.

Before you get excited about re-growing your favorite squash in the garden, it’s critical that you understand that hybrid varieties will contain seeds that are often sterile or produce fruits that aren’t true to the parent.

Saving from hybrid fruit in the hopes that you can recreate this year’s crop is a waste of time. Taking the steps to harvest seeds, dry them, and store them properly will not allow you to grow these squash once again. If this is new information to you, then your first step should be to confirm whether your plants are hybrids or not.

For example, ‘Carnival’ is a hybrid winter squash. Gardeners love it, because it’s the best of both worlds. It’s a fun and unusual-looking variety that looks great in fall decor, and it’s also delicious and easy to incorporate in lots of cozy meals. Because ‘Carnival’ is a hybrid, you cannot collect the seeds and grow more ‘Carnival’ next year. They will germinate with different traits than the original hybrid. You have to buy them from a reputable seed seller.

If you’re not sure if your plants are hybrids or not, simply do a little research. Hopefully you still have the seed packets or plant tags, which may tell you if they’re hybrids or not or should at least tell you the plant’s name, so you can Google it. 

If a plant is labeled “heirloom,” then you can definitely re-grow it from seed. Additionally, if your plant is just a generic classic like “butternut” or “zucchini,” it will probably be true to type as well.

If you’re simply not sure, proceed with caution but proceed nonetheless. Even if you are unable to grow the same squash next year, you will still learn a lot and will be better prepared for next year with more knowledge and experience.

Avoid Cross-Pollination

A close-up shot of an organic vegetable crop that is blossoming with yellow vegetables in an outdoor area.
Choose the right species because some can cross-pollinate with each other.

Another potential pitfall that could get in the way of your seed saving operation is cross pollination. If you are growing multiple types of squash at the same time, pollinators may cross-pollinate. This means that any collected seeds may produce a hybrid of the two parent plants.

You could have exclusively heirloom varieties in your garden, but if the bees cross-pollinate them, the next generation will ultimately produce different-looking fruit. This is difficult to manage, since you simply can’t stop mother nature. 

Preventing Cross-Pollination

To prevent cross pollination, choose your squash carefully. There are a few major species, and the varieties within those species can cross-pollinate with each other. Those from the different species are much less likely to cross-pollinate.

  • Cucurbita pepo includes pumpkins, delicata, zucchini and more.
  • Cucurbita moshata includes butternut squash.
  • Cucurbita mixta includes crookneck types.
  • Cucurbita maxima includes Hubbard, banana squash, and more.

For example, if you are growing zucchini and pumpkins at the same time, there is a high likelihood that they will cross-pollinate and will ultimately not be true to seed. Conversely, if you are growing pumpkins and butternut, it’s safe to guess that they probably won’t cross-pollinate and will indeed be true to seed.

Make a list of all the Cucurbita species you’re growing at the same time. Confirm that you know the specific species for each, and compare. You may discover that you’re growing multiple within the same species, and cross-pollination is likely. 

If you’re absolutely thrilled with specific zucchini this year and want to grow them again—but you’re growing them right next to some pumpkins—it’s not safe to assume that collecting and cultivating the seeds will yield what you are hoping for.

However, seeds from the prized crookneck squash you’ve been delicately caring for all season in this hypothetical scenario should be reliable for next year.

Harvest At The Right Time

A focused shot of a person wearing a blue shirt and jeans holding various vegetable crops that grows in the summer with colors ranging from dark green, orange and yellow.
Make sure the crops have had enough time to develop.

If these two major hiccups have been avoided—possibly attempting to save and re-grow hybrid varieties and possibly trying to re-grow seeds that were cross-pollinated—you should be in a great spot to save for next year’s garden.

Before you sever a big, beautiful acorn squash from the vine and start cutting it up, you need to make sure it’s had enough time attached to the plant to grow, start developing seeds, and fully mature.

Mature vs. Immature

Consider zucchini. Usually, we harvest and eat zucchini when it’s young and tender. We intentionally remove these fruits when the seeds are not yet developed because their texture isn’t appreciated. If you wanted to save seeds from a zucchini, you’d need to let it sit on the vine much longer than usual.

Meanwhile, we leave pumpkins for Halloween carving on the vine until they’re fully ripe, with tons of mature seeds. This is a pretty cut and dry scenario, as most gardeners know when pumpkins are fully ripe. Other winter varieties are harvested late in the season when their seeds are mature, too.

For more unusual varieties of squash, when growers don’t know their ideal color, the timing can be a bit more challenging. Discovering the perfect time can be even more confusing for summer squash varieties that we harvest young, such as zucchini and patty pan types.

A good rule of thumb is to wait for these squash to reach their mature size and then start slightly changing color. Once their color begins to shift, they’re not going to get any bigger. At this point, the rinds should begin to harden as well. If you can’t easily dent the rind with your fingernail, then the fruit is likely fully ripe (and so are its seeds).

Scoop Out As Much As Possible

A focused shot of a round orange vegetable crop that is sliced in half showcasing its organic matter on a wooden surface.
Use a clean knife to cut the crop in half and take a spoon to scoop out the insides.

You’ve spent all season carefully growing your beloved squash. You’re confirmed that the variety should be true to seed and that it was unlikely cross-pollinated. You’ve confident that the fruit is mature, with well-developed seeds inside.

Now it’s time to retrieve as many of these precious seeds as possible. While you may be thinking that you only need a few to grow this variety again next year, more is better. You want to hedge your bets and gather as many as you can.

If they’re not all viable or if some rot during storage, you’ll be glad that you have many more. Plus, you can easily share extras with friends. They will be particularly advantageous to your neighbors, for whom the plants should grow equally well in your local conditions.

How To Scoop and Rinse

Use a clean, sharp knife and gently cut the squash in half. Using a large spoon, scoop out all of the seeds. At this point, don’t worry about removing all of the goopy flesh. Just focus on getting 100 percent of them. Transfer into a clean glass jar.

Add some water to your jar of goopy innards, and put a lid loosely on the jar. You want to leave this jar alone for a day or two, which should encourage its contents to ferment just slightly. This process breaks down a gelatinous lining that many seeds have and will allow them to dry fully for long-term storage.

After a day or so, pour the contents of the jar over a fine mesh strainer to remove the liquid and the pulp. Be sure to rinse all the goop off. A sink sprayer attachment can make a significant difference. If you don’t have one, try spraying them (still in the strainer) with an outdoor hose. 

Dry Thoroughly

A close-up shot of an organic vegetable crop's germ that is drying on top of a wooden surface.
To dry them, spread them over a paper towel.

Now they must be dried thoroughly. If you do not dry them properly, they can collect mold over time and can even rot. The last thing you want is to retrieve the fruits of your labor in early spring to find that they’re in a state of decay.

An easy way to dry them is to lay them out in a single layer across a paper towel or a brown bag. Make sure that none of them are overlapping; they need to be in a single layer. Set them in a dry, cool place and wait for them to dry. If you’re patient, you can do this on the kitchen counter. (If you have young kids or pets who like to get into things, the kitchen counter may be risky.)

Quicker Methods

Another way to speed up the process is by placing them in a dehydrator. Usually, setting the dehydrator to about 115 or 120°F (46-49°C) is ideal. Consult the directions on the dehydrator for specifics, and set an alarm on your phone so that you don’t forget that the dehydrator is on.

You could also put them in the oven. Place them in a single layer on a lined sheet in the oven at 150°F (66°C) for about an hour. Be careful not to leave them in the oven for too long. You don’t want them to burn, especially after all your hard work.

You will know that they’re dry enough when they pass the snap test. To conduct this test, simply sacrifice one of your seeds by bending it in half. It should snap cleanly in two, implying that it’s fully dehydrated. At this point, there’s no need to worry about excess moisture that could cause rot.

Store Properly

A close up shot of three jars with a the dried germ of an organic vegetable crop that is placed indoors.
Avoid storing in humid areas and choose a cool, dry place.

Presumably you won’t be attempting to germinate until next spring, or possibly late in winter if you intend to start the plants indoors. This means you will need a place to store seeds properly and safely.

Even though they may be fully dehydrated, they are still at risk of molding and decaying if kept in a humid area. Often, our pantries and closets are more humid than we realize. Definitely avoid storing in humid areas like bathrooms and laundry room closets, but you may also want to skip the kitchen pantry or garden shed in favor of a garage.

Cool and Dry

Dry and cool is the best case scenario. A garage or a dry basement is your best bet. If you already have a spot where you store winter squash and root vegetables in winter, this is probably a good location for storage. Consider whether your garage gets hot, which is sometimes a problem in warmer regions.

Sealed

Put your seeds in a sealed jar to prevent any moisture from getting inside. Really, any sealed container will do. You’re mostly trying to keep bugs and other critters away. You can also add a pack of silica gel in the jar to further absorb any excess moisture that you may have missed. 

Don’t forget to label your container, especially if you’re saving multiple types of squash seed. Write down the name of the plant and the date of harvest. 

Freezing

You can also freeze them, as long as they are truly and completely dry. This is sometimes the best option when we don’t have a cool, dry alternative. If you’re in an apartment thinking you don’t have an ideal spot—try storing in the freezer.

However, if you’re using the freezer for storage, note that temperature fluctuations can cause germination issues. If the power goes out, for example, germination may begin.

Test Viability

A top view shot of a vegetable crop's germ soaking in water on top of a wooden surface in a bright well lit area.
Test the viability by soaking in water. Those that sink are viable.

When you’re ready to use your seeds, you may want to test their viability first. If you’re starting a bunch of them in a flat, you may not mind if a lot of them don’t germinate, but if you’re direct sowing, you’ll want to know in advance if they’re viable.

Stored seeds often last up to four years when dried and stored properly. Of course, there’s always variability in mother nature. Some may not last as long, while others may last far beyond the 4-year milestone. 

Sink/Float Test

Fortunately, there’s an easy way to eliminate those that are not viable right away. It’s called the “sink/float” test. All you need is a glass of water. Submerge your seeds in the water and set a timer for 15 minutes. 

Once 15 minutes have passed, return to the glass to see which ones have sunk and which are floating. The floaters are not viable. Those that sank, however, should be good to go. Now you can start your squash seeds with more confidence.

Despite our best attempts to do things the correct way, sometimes you just get a bad batch or didn’t realize that something else was going wrong, such as higher humidity in your basement than usual.

This is why it’s so important to save as many as possible, as indicated earlier, so that you have a high chance of at least some of them remaining viable. Good luck germinating! 

Share This Post
A tall, sturdy stem supports clusters of vibrant green Brussels sprouts nestled between broad, glossy leaves, ready for harvest.

Vegetables

How and When to Harvest Brussels Sprouts: 11 Pro Tips

Not sure about exactly when to harvest Brussels sprouts? How do you get the most out of each plant, and how do you do so without causing damage? This long-season veggie is a bit different from its other brassica cousins. Plant biologist Emily Estep will walk you through a series of tips to make sure you’re on the right track.

Close-up of a gardener with blue pruning shears preparing to prune a squash plant with large green foliage and oblong light green fruits.

Vegetables

How to Prune Squash Plants for Bigger, Better Yields

Many vining plants benefit from pruning, and squash is no exception! If you want to maximize your yields, consider pruning these rambling vines for increased pollination, airflow, and squash production. Former organic farmer Logan Hailey explains how to prune the simple way.

Dry red hot peppers with wrinkled bodies stored in a glass jar for long-term preservation.

Vegetables

How to Dry and Store Hot Peppers

Hot peppers grow dozens of fruit per plant! Preserve those excess harvests with these tried and true preservation methods. Follow along with pepper gardener Jerad Bryant to learn how to best dry and store hot peppers.

Many flowers of showy plants for bees butterflies, serving as the flower's pollinators

Ornamental Gardens

23 Showy Plants That Feed Bees and Butterflies

Whether you want to encourage healthy bee populations or just simply love watching the butterflies, you’ll want to plant an array of showy plants that feed these fragile pollinators. These plants can add color and texture to your garden. Plant biologist Emily Estep walks you through a list of bold, flowering plants that bees and butterflies adore.