Re: CULT:JI Heat

I have had three JIs bloom. They are beautiful and worth the extra effort. The blooms
don't seem to hold up too well in the hot weather we are getting now
 (high 80s low 90s) . Do they like a more mild climate or do certain cultivars do better in the heat 
of So.Cal.?
Steve,
When you grow JI, you should forget anything you know and expect about growing irises and start with a clean set of expectations. First of all, in the best of growing conditions, each individual flower lasts for only 2 days. During that time, the flower may be changing in size, proportion and color. It is not unusual for a  flower to be be a full 2" larger by the second day. By the end of that day, the flower is rapidly fading. Each terminal end usually has 2 flowers which should not bloom at the same time. Some cultivars show no branching, no matter how well grown, while others will branch IF they are happy. If you only have first year plants, you may only have one or two bloom stalks and no branching. You can expect only 4 days of bloom from one stalk and the flower on the first bloom after transplanting is rarely up to show quality. You may ask, "Why bother?" Well, by the third year, on a well grown cultivar, you may have 40+ bloom stalks, which do not all open the same day. "Springtime Snow", my earliest bloomer, is still showing color after 3 weeks!

Now, specifically to the question of heat affecting bloom, of course it does. Intense heat is likely to cause the buds to "melt" so that the flower will not open properly and it is worse if the humidity is low. The outer petal on the bud acts like a shrink wrap and the inner petals turn to mush. I have found this to be much worse when the temperatures soar just before bloom. I have set up sprinklers just for evaporative cooling when that occurs. Providing afternoon shade also helps. I find that 6 petal cultivars and those with less substance suffer more from the heat.

R. Dennis Hager
on Delmarva where it finally rained!
 
 

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