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  • From: Don Yellman <don.yellman@webformation.com>
  • To: nafex@lists.ibiblio.org
  • Subject: [NAFEX] Germinating Petunias
  • Date: Tue, 02 Jan 2007 02:48:42 -0500

Jerry:

Germinating very fine seeds like petunias, geraniums, impatiens, portulaca
etc. can be a challenge. One where a small sniffle can bring disaster. I
usually work with a magnifying glass, but easy it's not. I wonder if you
could improve your procedure by using transparent plastic covers to maintain
humidity at the surface. I use plant trays with close-fitting clear plastic
domes, which will hold 8-10 individual 4-in. pots. It shouldn't make much
difference what planting medium you use, so long as it is sterile to prevent
damping off of tiny seedlings. If you can't find plastic domes, plastic wrap
might be a workable alternative. But the domes or wrap should come off as
soon as the seeds germinate to prevent overheating if they are on an electric
mat. I use 2 waterbed heaters in series with an ordinary 600W light dimmer
switch, and aim for about 80 degrees F, as measured by a thermometer inside
the dome.

If you are unsure of whether your planting medium is sterile, moisten it and
give it a zap in the microwave. I do this routinely with my 4-in. pots,
giving each group of 4 pots 3 minutes to reach temperature. You will see the
steam begin to rise from the planting medium, but if the plastic pots start
to melt and slump, that is too much. This practice does add a somewhat
time-consuming step to seed germination, but it completely eliminates damping
off, which is caused by soil fungal organisms. Let the soil cool down before
spreading the seeds on the surface. Tiny seeds ought to germinate even in
pure vermiculite if it is moist and warm. I think you might want to bump up
your germination temperature a bit, and cover as suggested above to hold in
the heat and retain surface moisture.

This may be an OT post, but hey. Let's call it Petuniex.

Don Yellman, Great Falls, VA




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