RE: iris DIGEST V1 #564

I am interested in the discussion of the effect of soil temperature on
seed germination and the health of irises.  I got the last of my summer
seed harvest into the ground last week, at least three weeks later than
last year.  They had been dried, soaked for ten days with frequent water
changes then kept wrapped in wet cloths in a black plastic bag in the
bottom of the frige for three months.  The seeds looked good, fat and
firm.  I planted them six inches apart and covered them with seed
blanket suspended about eight inches above them.  

After reading Linda and Griff's comments, I took my soil thermometer out
and found that the temperature under the cover at noon today was 68
degrees F.  Soil temperature out from under the cover was 64 degrees,
the same as the air temperature.  I expect the little plants to start
showing up by the end of January and for germination to be mostly
complete by the end of February.  Seed blankets will come off about a
month later when danger of frost has passed.

This is the third year I've used this method with good results so far.
Last year I had two plantings, one in mid-November and the second Dec.
30.  The earlier planted ones have done notably better than the later
ones many of which succumbed to heat last summer.

I used the soil thermometer last July to test the effect of shade
screen.  Under the screen on a 110 degree day, the soil registered 95
degrees, while outside the screen the soil temperature read 105 degrees.
The irises stayed green under there while the ones that didn't get any
shade turned yellow, but I had very little rot in either place.  I let
them go much drier than usual, watering them only every two weeks.  What
rot I had came after an October rain when the weather was much cooler.  

Francelle Edwards

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