[NAFEX] Germinating Petunias
don.yellman at webformation.com
Tue Jan 2 02:48:42 EST 2007
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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