rosemary leaves are turning black - hot weather - too much water

christina01862July 21, 2006

I have a rosemary in a pot in my home. It was doing great for a week or two, but now it is dying. I have read here, that it shouldn't be watered to much, but the leaves have started to turn black and dry out, so I have been giving it more water. This does not seem to be helping. It has been very hot and humid here (95 degrees) could it be the weather or does it look like it might have a disease.

I do not see any bugs or strange growths on it, I have no idea what I am doing wrong.

Here is a picture, is this plant a lost cause?

Thanks for any help!

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could be a fungus... or maybe sun burn, is it right next to a window? Is your HOUSE 95 degrees? Don't worry about that... it's way over 100 here and the rosemary is doing fine. If it's not 'windowburn' and not a fungus, it's definitely over watering...

    Bookmark   July 21, 2006 at 12:27PM
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I must say I've seen better rosemary plants! I notice that your pot is quite small, and also that it has no saucer underneath. So where does the excess water go when you give the plant a drink? I get the feeling you haven't given it enough water, actually, or that it's so rootbound that the roots can't access the water. I also notice that there is quite a bit of new growth on it that looks quite healthy. I suggest you repot it into a larger pot and cut it right back, leaving perhaps one healthy bit to help it regenerate. Or take cuttings of the healthy bits and start a new plant altogether. Rosemary is seldom happy indoors, so if you can take it outside, it stands a better chance of a happy future.

    Bookmark   July 21, 2006 at 6:30PM
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katwomn59(8b-Austin, TX)

That looks similar to what happened to my rosemary. I think it was too much water and not enough drainage. I use a fast draining mix but the screen I used at the bottom of the pot was apparently too fine meshed so the roots and fine grains from my mix accumulated on the bottom and impeded the drainage (at least thats my theory). And mine was outside in the heat (which is why I was watering it a lot). You might try cutting it back some and putting it outside. Rosemary can take quite a bit of heat.

    Bookmark   July 21, 2006 at 6:35PM
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Christina, that is definitely a fungus caused by too much water. Rosemary is a hot weather, dry weather plant, made to handle low moisture. Notice how thin the leaves are...water enters the roots, travels up the stem and exits through tiny holes in the leaves. Water exits a very thin leaved plant like rosemary slowly, so the more water you give it, it starts staying in the root area and rotting the roots. Pruning it at this time is a mistake, because you will be removing more leaves that the plant needs to get rid of the water. Try cleaning the diseased leaves of the stem, let the root ball dry out quite a bit and remove any dishes from underneath. You mention the pot is "in" your home. Make sure it gets at least 4 or 5 hours of sunlight, and again, minimize the water. It is hard to reverse this problem on rosemary once it starts but it can be done. Good luck.

Here is a link that might be useful: The Herb Garden

    Bookmark   July 27, 2006 at 8:04AM
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The heat is not the problem with our garden herbs, the humidity and excessive rain is another matter. I have never had success with Rosemary in the house. I do have success now with Rosemary in an outdoor, raised bed (good for very wet zones). If cold is a problem in winter, try Arps (I believe it is hardy to at least 6b zones). I have noticed however, that some of my plants have been suffering from the excessive rainfall and humidity, and there's not much we can do about that.

    Bookmark   July 27, 2006 at 10:52PM
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I have also tried Rosemary as a houseplant with no success. I like to keep one on the kitchen windowsill, so what I do now is rotate plants in and out. When the growth starts to get "leggy" and soft in the house, I move it out. Even in a window, the light inside just isn't enough, and at low light conditions, rosemary gets really soft. When that happens it is even more susceptible to disease and rot. The combination of soft growth, low light, high humidity and possibly poor drainage is a "worst case scenario" for rosemary. A plant growing outside in full sun will normally have tougher leaves with shorter internodes and will be more resistant to disease. But like I said, that doesn't stop me from continuing to bring them into the house for convenience. I just know they are "guests" and can't stay for long.

    Bookmark   July 28, 2006 at 12:11AM
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I have a very nice rosemary plant that I've been growing indoors for a while now and it's doing well...probably 8" to 10" tall and branching nicely...almost bonsai-like. I have been heeding the advice here....not overwatering. But I am also careful not to let it dry out. The tag for the care of the plant that came with it said that rosemary won't recover once completely dried out.
When I have access to my desktop computer, I'll post a pic of it on photobucket. I also have had good success indoors with lettuce leaf basil, greek basil, lime mint and pineapple sage. I've plans to start some Kentucky Colonel mint indoors and some sweet basil. The lime mint and pineapple sage was just planted as an experiment. I had some cut and indoors in vase and they both developed very nice looking roots in the water, so I transferred them to a soil medium, and they did well.
All my indoor plants are in clay pots like the one used by the original poster of this thread.

    Bookmark   July 29, 2006 at 4:13PM
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Please help!
Why are the leaves on my Rosemary cutting turning black??
The cuttings were grown in a glass of water and they loved it! Roots and all, transferred them into a pot and now I have black leaves! Any ideas for me???

    Bookmark   August 3, 2011 at 2:45PM
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