Processing Squash Seeds

Harvest squash when skin is hard and difficult to scratch with fingernail. If time allows, cure/ripen indoors or in a shaded area for 3 weeks or longer (optional).

With large seeds and a dryish interior, squash is one of the easier fruits to save seed from, a fun project to do with kids. You can choose from either Dry Process or Wet Process.

Dry Process (no water necessary)

1. Cut open the squash and scoop out seeds. 
2. Use your fingers to separate the seeds from the stringy interior mass. 
3. (Optional: Rinse seeds in a colander under a stream of water, agitating to remove any remaining debris stuck to the seeds.) 
4. Spread seeds in a single layer on a plate, cookie sheet or screen and let dry, stirring occasionally to aerate evenly and prevent sticking.

Squash seeds are easily separated from the stringy flesh

 

Wet Process

1. Cut open the squash and scoop out seeds.
2. Place the seeds with pulp in a large bowl or bucket. Add twice as much water as the seed/pulp mix and stir vigorously to loosen seeds from pulp. If the pulp clings tenaciously to the seeds, allow the seeds to sit in the water overnight or up to a day or so. Stir again vigorously and perhaps massage the pulp with your fingers to finish loosening the seeds.
3. If most of the seeds sink to the bottom, these are good, viable seeds and you can proceed to step 4. 

   If many seeds are floating, pour everything into a strainer with holes smaller than the seeds. Spray with water and stir or massage the seeds to clean off the pulp. A spray nozzle helps with this. Then proceed to step 5. 

   In many cases, good, viable seeds are dense and will sink to the bottom; poor quality seeds and pulp tend to float. However, some seeds, e.g., C. maxima seeds, float whether they are good or bad, so all must be collected, dried, then winnowed (see below).  Check out this discussion for further thoughts on sinkers and floaters.

4. Pour off floating seeds and debris and add more water. Repeat the process until only heavy seeds are left. Pour seeds into a strainer and allow to drain.
5. Wipe the bottom of the strainer to remove as much moisture as possible. Thinly spread the seeds on a glass or ceramic dish, cookie sheet, or window screen, and let dry. Do not dry on paper as the seeds may stick to it. Stir occasionally to aerate evenly and prevent sticking.

Air drying squash seeds in a styrofoam tray

Seeds should be dried as quickly as possible to prevent molding or germination. If your climate is humid, a dehydrator set at 100 F or less can be useful for drying. However, before putting seeds in, be sure to check that it reliably maintains this temperature without fluctuating. An increase of 20 degrees or more can kill the seeds.

A safer alternative is to run a fan on a low setting to increase air circulation in the room. This will help move moisture away from the seeds more quickly. Be sure to adjust the distance between the seeds and the fan to avoid blowing the seeds away!

Seeds are dry enough for storage when they are not easily dented by a fingernail and snap crisply when bent in half. Mature viable seeds will be firm and plump, not brittle or hollow. 

 

Winnowing

If your dry seeds are a mix of good heavy seeds, light undeveloped ones, bits of pulp, and/or the translucent papery skin from the surface of the seeds, you may want to separate the good seeds from the debris to save storage space and also for sharing purposes. Separation is easily achieved using the ancient, low-tech method of ‘winnowing’, which involves airflow to separate the heavy seeds from lighter debris. Check out this video to see a demonstration of this method at its simplest. 

Alternatively, a screen or colander with holes smaller than the seeds can be used to sift out small, crushable debris.

Useful seed cleaning equipment

 

If you are storing the seeds before sending them to Going to Seed:

Ideally, store seeds in a cool, dry space in airtight glass or thick plastic containers, or plastic bags (freezer type, >4 mil thick). If rodents, insects and other seed eaters are a problem, glass jars, metal boxes or 5-gallon plastic buckets with tight-fitting lids offer good protection. If you are unsure of the dryness of your seeds, include moisture absorbent packs in the container to reduce humidity, or store in paper envelopes or cloth bags to allow moisture from the seeds to escape (with the caveat that these are not rodent- or insect-proof!) Keep in mind that your climate and storage space will determine the method that works best for you. If you’re a new seed saver, check your seeds regularly to catch problems before any damage becomes a total loss.

 

These sources discuss in more detail important points to keep in mind for drying and storage of seeds:

When Good Seeds Go Bad: How long can you store seeds?

Breed Your Own Vegetable Varieties by Carol Deppe, Chelsea Green Publishing Co., p 255 (requires free account if accessing through Internet Archive)

The Seed Garden, L. Buttala & S. Siegel, eds., “Seed Quality and Storage”, p. 93 (Seed Savers Exchange), only some pages visible in this preview, must scroll down to p. 93 or 95 (Check your local public library for a copy. They may be able to order it if it’s not already in their collection.)