Rosemary - White powdery substance

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 Dan Charette { snipped-for-privacy@thesonicfrogFUZZ.com} Remove the "FUZZ" from my e-mail address to contact me.
"I may not always be right, but I'm never wrong."
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I have yet to see a Rosemary of any kind, brought inside for winter, go without powdery mildew. It is simply too humid in most homes for Rosemary. A sunny window, even southern exposure, is still less sun than if you had it outside in the shade. They do not thrive indoors.
opined:

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I live in Alberta and I have a thriving 15 yr old rosemary plant in my kitchen, in a south-facing bay window. It spends only 3 months of the year outside. I've never had mildew on it, but then, I might be lucky. It grows like the clappers and I have to crop it frequently. The main stem is now about 1.5" in diameter.
Graham
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That is quite rare. I wonder if it's the bay window part? If you bay window sticks out, the plant may be receiving more light than if you had a flat window. You've mastered it, that's for sure. Many people water their plants to death. Me included!
Victoria
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opined:

Because it is vigorous, it's a heavy drinker. An early sign that it needs water (+ a small amount of Schultz) is a slight twist in the leaves that becomes more pronounced if you ignore it. During the summer, I have to water it nearly every day. I now have some French lavenders in pots that are even more vigorous. The Spanish is very delicate and vulnerable to aphids and the English lavender seems to be more susceptible to spider mites. Graham
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That's interesting. I have Rosemary 'Tuscany Blue' and have had it for about 6 years, moved it 200 miles from Dallas to Austin and our median temperatures here in summer are 95-100 degrees for about 4 months, and I never watered it yet. Maybe once when it was first planted.

Eh, lavender. I have some. It's always a mess. I give up on it.
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In article snipped-for-privacy@suifdgj.net says...

I brought two inside for the winter and one looks like it's dead. Will it come back next Spring? It seems had I left it outside in the cold it would have fared a lot worse. I thought Rosemary was perennial. How do you keep it going year after year if you don't bring it inside?
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On Sun, 14 Dec 2003 06:39:32 -0600, Mark Anderson

I keep mine outdoors and they are growing well. They keep their leaves during the winter and don't mind freezing temperatures. Indoors, you need to provide as much sunlight as possible and be careful about overwatering. No fertilizer.
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says...

outside!! I have mine in a south facing bay window. It drinks like a fish and I fertilize it. It has been rootbound for years but according to some authorities, this is the way to treat it. Graham
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There are many varieties of Rosemary. Like many herbs it seems to grow well without special attention. I've read that it doesn't like strong winter winds, though there is little wind here between two mountain ranges. The cutting I rooted last spring are growing well and I'll need to start trimmimg it to the shape I want (Christmas tree) else it will eventually look straggly like its mama. Nice dark green color and bushy herb.
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There is a variety which will tolerate, oh, USDA Zone 6b in a protected situation. Against a southern side of the house, but dry. Rosemary 'ARP' is one of the more hardy types. Another was developed by Madelaine Hill, it may be called 'Hill' for all I know. I don't recall. Does anyone remember the one she found which is hardy?
V
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opined:

Well, down here in Texas I've seen Rosemary 5 feet tall and wide. They get rather large here, needless to say. Many people use them as evergreen hedges. You can't beat the fragrance. Most every raised wall has prostrate Rosemary dripping from it. A beautiful and useful plant.
V
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I'll have to admit that my old Rosemary was a bit ratty appearing and had outgrown its allotted space, which is why I discarded it. I don't need that much Rosemary. <G> BTW, one of our local nurseries has Rosemary in pots for sale that were trimmed and decorated to resemble miniature Christmas trees. The scent and color were correct, but the word "tacky" still came to mind as I viewed them. I suppose making a buck is an American tradition, but....
John
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Graham
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I have a variety that has survived in Zone 6b for the past four years without any particular winter protection. Last fall I over wintered a cutting that rooted after being used as a county fair exhibit in my sun room. This spring I discarded the old plant that had become overgrown and woody and planted the cutting. in its place. It's doing fine. I find rosemary far easier to grow in 6b than lavender, which will not tolerate wet feet during the winter. Rosemary is far more forgiving and seems to thrive on a bit of water and fertilization during hot weather. BTW, the original rosemary had grown to 2 1/2' X 2 1/2' when discarded.
John
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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 nNJ usa z7ish
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rosemary is adapted to cool wet (well drained) winters. sf bay, z 15
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Man, are you one lucky dude! Paghat would kill to have a plant that produces that magical white powder that she sniffs up her nose.
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