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  • From: Don Yellman <don.yellman@webformation.com>
  • To: North American Fruit Explorers <nafex@lists.ibiblio.org>
  • Subject: [NAFEX] Microwaving Soil
  • Date: Sat, 12 Jan 2008 13:12:02 -0500

Jerry;

I sprout and grow out many seeds in my attached greenhouse structure each
winter, many of them maddeningly small, like moss rose, geranium, impatiens,
and petunia. As the old eyesight fails, I have taken to working with a
magnifying glass, but have to be careful not to sniff or sneeze or it's over,
since these seeds can be compared to dust. Spreading them evenly over the
surface of a flat is also a challenge.

The biggest problem I used to face with these and many other seeds was lack
of soil sterility, leading to damping off. Now, when I prepare a flat or
pot, I microwave the container for several minutes until the soil comes out
steaming, then plant when it cools down. How long to leave the soil in the
microwave depends on the power of your unit and the soil volume, but I
generally use 3 minutes for 3 full 4-inch pots, or a small flat. Damping off
dropped to zero after I began microwaving. You can use any soil/peat mixture
you happen to have around. The soil should be moderately moist to generate
steam.

I use clear, domed flats for seed starting, and two old waterbed heaters
linked in series with a light dimmer rheostat to supply bottom warmth, and
strike for about 80 degrees. Have to remember to turn it off each morning
when the sun comes out, but the domes come off in less then a week as the
seeds germinate, and then I don't have to worry so much about excessive heat
buildup.

Microwaving the soil has turned out to be the most important step I take in
my seed starting procedure, especially with expensive and very tiny seeds,
but also tomatoes and cucurbits.

Don Yellman, Great Falls, VA



  • [NAFEX] Microwaving Soil, Don Yellman, 01/12/2008

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