Tuesday, November 22, 2016

Fluid Seeding, aka Cornstarch Gel Germinating

Several sites recommend using a cornstarch gel for planting out delicate barely germinated  seeds, or as a medium for germinating them.  It's used because after a seed has germinated artificially it will continue to grow even though it's too cold for them to germinate in the ground.

In an area with a short growing season you can gain a couple weeks of growing time by pre-germinating. 

The claim is that the gel and sprouted seeds can be squeezed from a bag into the prepared seed bed without damaging the delicate new roots.  If you are germinating in a dish of gel, you can spoon a sprout and some gel and place it where you want it.  The gel cushions the roots during transfer and provides a small reservoir of moisture for the first few days.

I tried germinating seeds on a dish of gel because my success rate when planting directly is usually poor.  Keeping a garden plot damp during a seedling's delicate early days is not easy in the arid Southwest.
In short, it didn't work.  The gel liquefied and went sour and fermented before the seeds had sprouted.  In desperation,  I spooned the seeds from the decomposing gel and planted them anyway.  Some survived the experience, but only until the fence installer dropped all his tools and a couple of bags of concrete mix on them.  There's a reason my winter garden is late.

However, plenty of people on the web are claiming it works, so here's the way it's supposed to work.  I will try it again next spring before declaring it a total failure.

The recipe for 1 cup:

  • 1 cup of water
  • 2 teaspoons of corn starch (or more, depending on how thick you want the gel)
    The gel will thicken as it cools, and I can tell you from experience that 3 teaspoons per cup of water is way too much.  You want a consistency about that of pancake batter or medium gravy, not library paste.
Shake the cornstarch and water together in a container with a tight-fitting lid until there are no lumps left, then dump it into a small saucepan and bring it to a boil over medium heat.
It is done when it becomes almost transparent.  It will thicken as it cools.

CAUTION: Stirring too much after it has gelled will break down the gel and make it runny again.  Also, if you cook cornstarch too long, it un-gels and thins out again.

Squeezing Sprouts

If you have germinated seeds on paper towels, gently dump them into a plastic bag of cooled gel.  Mix it gently to distribute the sprouts.  Cut a corner of the bag to make a suitable size hole  and gently squeeze gel and seeds into the furrows. It's like squeezing icing out of a frosting bag.

Cover the seeds with the right depth of dirt.

Germinating and Spooning the Sprouts

The method I tried was scattering seeds on a shallow dish of gel to germinate.  In theory, they will sprout and you can use a spoon to transfer individual sprouts into the growing bed at the right distance, then lightly cover them. 

My seeds sprouted, but not fast enough. Soaking the seeds overnight before scattering them might make this work.


Fluid seeding at Colorado State:  http://www.colostate.edu/Dept/CoopExt/4dmg/VegFruit/fliud.htm

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