Introduction to Seed Saving, Part 2: Wet Seed Production

This article is a follow-up to the article from last week about High Mowing’s production of dry seed crops, highlighting Ruby Streaks mustard.  The Seed Production Farm grows approximately 12 acres of seed crops each year.

What are “Wet Seeded” Crops?
The majority of our late season crops are wet seeded.  Wet seeded crops are those that house the seed inside the fruit.  Pumpkins, watermelons, squash, cucumbers, tomatoes, and peppers are all wet seeded crops.  Wet seeded crops, like dry seeded crops, are easy to grow, save, and maintain.  We’ll follow our seed crop of Long Pie pumpkin through the wet seed extraction process.

HMS Seed Production Farm: Producing Long Pie Pumpkin Seed

We start wet seeded crops in the greenhouse.  Cucurbits grow quickly, so our Long Pie pumpkins are started in larger 24-cell trays.  With some cucurbit plantings, before transplanting we carefully dunk whole trays of transplants in a Surround WP and water mix.  Surround WP is a kaolin clay-based insect deterrent that we use to manage cucumber beetles, at least until the plants have established in the field.  We transplant with a waterwheel transplanter into black plastic mulch for added heat, and weed control.  During planting, transplants are fertilized with Neptune’s Harvest Fish Seaweed blend diluted in water.  If the weather is still cool, or for any plants that we don’t dunk with Surround WP, we cover transplants with remay.

Roguing

During the growing season plantings are weeded and rogued.  For example, zucchini must be single stemmed.  Any multi-stemmed zucchini—a genetic trait—are pulled (rogued) from the population before flowering.  Multi-stemmed zucchini do not put as much energy into producing fruit, so they are less desirable.  Zucchini reverts to multi-stemmed when not rogued.

Isolation of Cucurbits

As with any seed crop isolation is of the utmost importance.  Cucurbit crops, which are insect-pollinated, need a half mile isolation from any other plantings in the same species so that they don’t accidentally cross.  Long Pie Pumpkins are Cucurbita pepos.  This means that they will cross with anything else in that same pepo species.  This includes many of our pumpkins, all of our summer squashes, and several of our winter squashes.

Seed Maturity

Wet seeded crops are harvested at normal maturity.  Because we are not worried about the storability for keeping through the winter, and only interested in making sure that the seed is fully mature, pumpkins and winter squash are left to cure for two weeks extra after the plant has died (either from powdery mildew or from heavy frost).  This means that the Long Pie Pumpkin is allowed to turn completely orange in the field.

Seed Harvest and Extraction

Harvest: In preparation for extracting seed in the field, especially for larger cucurbits, we harvest all the fruit into piles on the black plastic

Extraction: We use the ‘Liberty 5000’ seed extractor to extract cucurbits.  Ol’ Lady Liberty has easily pulverized millions of pounds of fruit, extracting thousands of pounds of seed.  In 2012, we extracted three varieties of pumpkins, three varieties of summer squash, four varieties of winter squash, two varieties of watermelons, and two varieties of cucumbers.  Our seed extractor is indispensable to our seed farm infrastructure.  Tom named the extractor the Liberty 5000 because he figured it liberated him from 5000 hours of hand extraction of cucurbits per season…and that was back in 2002!

We tow the trailer-mounted extractor into the field with a pickup and toss the fruits into the hopper.  The process of extraction is partially gravitational and utilizes a small engine to turn a pulverizing drum at approximately 250 rpm and a screened turning barrel that turns around 20 rpm.  Smaller cucurbits, like cucumbers, are loaded into 5-gallon buckets and dumped into the hopper, while larger melons and squash are tossed into the hopper.  The fruits are pulverized by the pulverizing drum.  Tossing cucurbits, especially watermelons and pumpkins, into the hopper can quickly resemble a three point competition amongst the extraction crew.  I try to evoke a young Larry Bird, the man was lights out with a 20ft jump shot.

The pulverized mash falls down a diagonal shoot and into a turning hopper.  The turning hopper is outfitted with screens that correspond closely with seed size.  As the hopper turns, seeds fall through the screen, onto a copper deck, separating seed from most vegetable flesh, which drops on the ground and is left as a snack for the deer.  Seed is shoveled into 55-gallon drums in the bed of a truck. Inevitably vegetable flesh mixes with the seed.  The screens do keep this at a minimum however.  Drums are filled halfway with the seed mixture.  Once the seed crop is harvested into the back of the truck, we return to the warehouse and unload the barrels.  Labeling of drums is of the utmost importance at this point.  Remember: Label. Label! LABEL!

Seed Processing and Cleaning
The 55 gallon drums of seed and flesh are filled with water and left to ferment for two or three days.  The drums need to be stirred 5-6 times per day.  The fermentation process is not imperative for squash, melons, or pumpkins, like it is for tomatoes and cucumbers (fermentation is important to break down the gelatinous outer seed coat so that the seed is “primed” for germination).  However, fermentation does help to breakdown any flesh that remains after extraction, and makes the cleaning process easier. We ferment the seed/flesh mixture for approximately three days: just long enough to separate the flesh from the seed.  Seeds will germinate if they are fermented for too long.

After fermentation, seed is washed and dried.  We use a series of screens when washing and drying seed.  Seed/flesh mix is spread over the screens and washed with a hose with good water pressure.  We pick out any large pieces of flesh. After washing, seeds are spread on a 12x4ft wood framed screen to dry in the greenhouse.  Box fans are placed above and below the screened seed to increase airflow for drying.  When seeds are dried they are labeled, bagged and brought into the warehouse for germination testing and further cleaning.

Stats on our Long Pie Pumpkin Crop

  • One acre of pumpkins yields approximately 20,000 lbs of fruit
  • Once extracted, 500-600 gallons pulpy seed remains or 20 barrels once watered down
  • In 2012, we planted 1,500 Long Pie Pumpkin plants on 1/3 acre; yielding 208 lbs of seed
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2 Responses to Introduction to Seed Saving, Part 2: Wet Seed Production

  1. Thanks for the detailed description. Your extractor reminds me of my Squeezo fruit strainer. I may try it out for saving pumpkin seeds.

  2. lance b says:

    We love our Squeezo! let us know Laura how that works out.

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