[NAFEX] Germinating Petunias

Stephen Sadler Docshiva at Docshiva.org
Tue Jan 2 03:20:13 EST 2007

Well, technically, petunias are edible, including the fruit - so we're not
completely off topic...

-----Original Message-----
From: nafex-bounces at lists.ibiblio.org
[mailto:nafex-bounces at lists.ibiblio.org] On Behalf Of Don Yellman
Sent: Monday, January 01, 2007 11:49 PM
To: nafex at lists.ibiblio.org
Subject: [NAFEX] Germinating Petunias


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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