Saving Squash Seeds: Learn About Squash Seed Harvesting & Storage

By: Amy Grant

Have you ever grown a blue ribbon hubbard squash or another variety, but the next year the crop was less than stellar? Perhaps you have wondered if by collecting seeds from the prized squash, you might get another crop just as amazing. What is the best method then for squash seed collection and saving those premium squash seeds?

Squash Seed Harvesting

More and more often of late, plants and seeds available at the local home and garden center are comprised of hybrid varieties that have been engineered to retain selected characteristics. This hybridization, unfortunately, breeds out the plants’ innate ability to adapt to inhospitable or challenging conditions. Luckily, there is a resurgence to save some of our heirloom fruit and vegetable varietals.

Saving squash seeds for future propagation can be a bit of a challenge since some squash will cross pollinate, resulting in something less than appetizing. There are four families of squash, and the families don’t cross pollinate, but members within the family will. Hence, it is necessary to recognize what family the squash belongs to and then only plant members of one of the remaining three nearby. Otherwise, you will have to hand pollinate squash to maintain a “true” squash for squash seed collection.

The first of the four major families of squash is Cucurbit maxima which include:

  • Buttercup
  • Banana
  • Golden Delicious
  • Atlantic Giant
  • Hubbard
  • Turban

Cucurbita mixta counts amongst its members:

  • Crooknecks
  • Cushaws
  • Tennessee Sweet Potato squash

Butternut and Butterbush fall into the Cucurbita moshata family. Lastly, are all members of Cucurbita pepo and include:

  • Acorn
  • Delicata
  • Pumpkins
  • Scallops
  • Spaghetti squash
  • Zucchini

Again, back to hybrid varieties, often the seed is sterile or doesn’t reproduce true to the parent plant, so don’t try squash seed harvesting from these plants. Don’t attempt to save any seeds from plants that are afflicted with disease, as this will likely pass to the next year’s generation. Select the healthiest, most bountiful, flavorful fruit to harvest seeds from. Harvest seeds for saving from mature fruit towards the end of the growing season.

Storing Squash Seeds

When seeds are ripe, they generally change color from white to cream or light brown, darkening to a dark brown. Since squash is a fleshy fruit, the seeds need to be separated from the pulp. Scoop the seed mass out of the fruit and place it in a bucket with a bit of water. Allow this mix to ferment for two to four days, which will kill off any viruses and separate the good seeds from the bad.

Good seeds will sink to the bottom of the mix, while bad seeds and pulp float. After the fermentation period has completed, simply pour off the bad seeds and pulp. Spread the good seeds on a screen or paper towel to dry. Allow them to dry completely or they will mildew.

Once the seeds are absolutely dry, store them in a glass jar or envelope. Clearly label the container with the variety of squash and the date. Place the container in the freezer for two days to kill off any residual pests and then store in a cool, dry area; the refrigerator is ideal. Be aware that seed viability decreases as time passes, so use the seed within three years.

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Seed Life Chart

To help you figure out if your seeds are still viable, refer to the following chart, which indicates the life expectancies of certain types of vegetable seeds stored under ideal conditions. The chart has been modified from D.N. Maynard and G.J. Hochmuth, Knott’s Handbook for Vegetable Growers, 4th Edition (1997).

Vegetable – Years
Asparagus – 3
Bean – 3
Beet – 4
Broccoli – 3
Brussels Sprouts – 4
Cabbage – 4
Carrot – 3
Celeriac – 3
Cauliflower – 4
Celery – 3
Chard, Swiss – 4
Chicory – 4
Chinese Cabbage – 3
Collards – 5
Corn, Sweet – 2
Cucumber – 5
Eggplant – 4
Endive – 5
Fennel – 4
Kale – 4
Kohlrabi – 3
Leek – 2
Lettuce – 6
Muskmelon – 5
Mustard – 4
Okra – 2
Onion – 1
Parsley – 1
Parsnip – 1
Pea – 3
Pepper – 2
Pumpkin – 4
Radish – 5
Rutabaga – 4
Salsify – 1
Spinach – 3
Squash – 4
Tomato – 4
Turnip – 4
Watermelon – 4

Cleaning Them

Squash seeds need to be cleaned before they can be dried because fruit fibers stuck to the seeds can rot or mold, destroying the seeds. The process of removing the fiber debris from the seeds begins with filling a container with cold water and adding the seeds. Let the seeds sink to the container's bottom, and the debris will float on the water's surface. Discard all seeds that float to the surface because they are hollow and will not germinate. Pour off the dirty water, and refill the container with fresh cold water. Stir the seeds with a spoon or your hands to loosen more debris, and pour out the water again. The procedure must be repeated until the seeds are clean. Then the seeds can be poured into a colander to remove the excess water. Pat the seeds dry with a paper or cloth towel.

  • Squash seeds need to be cleaned before they can be dried because fruit fibers stuck to the seeds can rot or mold, destroying the seeds.
  • Then the seeds can be poured into a colander to remove the excess water.

Planting Location

Plan ahead by planting your yellow squash far from all other members of the Cucurbita pepo species, including zucchini and certain pumpkins. Doing so will prevent your yellow squashes from cross-pollinating with non-yellow squashes and producing seeds that result in plants that have fruits exhibiting traits of both parent plants' fruits. In open areas, Cucurbita pepo species' plants pollinate other such plants up to 1/2 mile away. Trees, fences and buildings reduce the problem. So plant your yellow squash in a protected location separate from similar vegetables. Also, plant only one non-hybrid variety varieties don't always cross-pollinate well, and seeds from hybrids don't produce plants true to the parent plants.

Storing Seed

Once completely dry, seed should be stored in a cool dry location. If you have room, storing in your refrigerator is ideal. Make sure the storage containers are completely dry. Envelopes or ziplock bags work fine, as well as baby-food jars, etc. Most seed will stay good for at least 3-4 years. Don’t forget to label everything with both the plant name and date!

An Additional Caution

Some diseases can be spread through seed from infected plants. Following is a list of some of the diseases that can be spread through seed:

  • All Cucurbits
    • Angular Leaf spot (especially cucumber)
    • Gummy stem blight
    • Scab
    • Squash mosaic virus
  • Muskmelon, Cucumber, Watermelon
    • Anthracnose

If you know that your plants have any of these diseases, you should not save the seed. However, most people will have no idea whether their plants are infected with particular fungi, bacteria, or viruses. A good rule of thumb is to simply save seed only from plants that have healthy, normal-looking leaves and fruit.

  • Seed Saver’s Exchange. 3076 North Winn Road Decorah, IA 52101 Phone: 319-382-5872
  • “The Organic Seed Grower” by John Navazio. 2012. Chelsea Green Publishing, White River Junction, VT.
  • “The Manual of Seed Saving: Harvesting, Storing, and Sowing Techniques for Vegetables, Herbs, and Fruits” by Andrea Heistinger 2013. Timber Press, Portland, OR.

How to Collect Seeds From Zucchini Squash

Avid gardeners are regular when it comes to saving seeds from one year’s crop, for the purpose of cultivating next year’s garden. While it might seem easy to just pull a couple of seeds from a plant, and save them for planting, there is a particular method to it, and several factors that need to be kept in mind.

Things Required:

– Zucchini
– Bowl
– Spoon
– Paper towels
– Envelope or paper bag

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The first and most important step is to choose a zucchini squash from a plant that is healthy and green, and has always produced flavourful, good quality fruit. You reap what you sow, so make sure the fruit you choose for collecting comes from a plant with a good history. Once you pick a fruit, make sure you cut it open and have a little sample – do not choose fruits that come from diseased plants, are from the very end of the harvesting season, or taste bitter.

Next, use a sharp knife to slice the zucchini in half. Place the halves on a flat counter, with the cut side up, and use a spoon to scrape out the seeds from the centre of the fruit. At this point, the seeds will be trapped in the pulp of the fruit, so give them a good wash, to separate the seeds from the pulp. However, while it is essential to wash them, make sure you do not soak the seeds.

Then, spread the wet seeds out onto a flat, clean tray, and look through them carefully, inspecting them. Remove and discard any seeds that are crushed, flat, or do not appear to be in very good condition. These will not bear any fruit.

Now that you have washed the seeds, and removed any bad ones, proceed to spread them all out on a paper towel, and let them air dry naturally. As they dry, keep the seeds away from any moisture, or from excessive heat – for example, do not keep them near your kitchen sink, or put them out to dry in the sun.

After the seeds have dried completely, you can store them in paper bags, or even in envelopes. Make sure you select a storing space that is cool and dry – this will increase the longevity of the seeds, and they will keep for a couple of years, as long as you make sure they are not exposed to any sort of moisture or extreme heat.

Watch the video: Partykas Farm A Field of Pumpkins.

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