GardenBanter.co.uk - View Single Post - Rosemary

11-12-2003, 06:02 PM

From: Dan Charette
Date: Thu, Dec 11, 2003 9:54 AM
Message-id:

HI all...

I have a perplexing question regarding rosemary. I'm in Nebraska and
I've got some rosemary growing in pots that I took in from this
summer's growth outdoors. The pots sit in a southern exposure window
and they get as much sun as is possible this time of year. One of the
plants seems to be growing exceptionally well, but it has developed an
odd white powder on many of its leaves in the last day or two. This
powder just appeared out of the blue. It seems to me that I've sen
this before but I can't remember exactly what this means. Does anyone
have any ideas?
Thanks...

Dan

The tricky thing with rosemary indoors in wintertime is to make sure it doesn't
get too dry or hot. The dry air and the sunny window can contribute to powdery
mildew, which sounds like what you're seeing. Make very sure that the
(well-drained) potting soil absolutely never ever dries out completely and that
there isn't an extreme heat build up that remains around the plants overnight.
The powdery mildew won't necessarily cause the death of the plants but the
environmental factors that cause it may do just that. I occasionally see a
touch of PM on my overwintering pots of rosemary, but I keep them going
strongly anyway.

I haven't tried it but some recommend a dilute spray of baking soda (one-half
teaspoon to one gallon water) to be used at the first sign of powdery mildew.

Best,
Tyra
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