cosmos stubbornly refuses to bloom

I haven't planted cosmos in several years. I planted the dwarf variety 3 years ago, and have just enjoyed the chance reseeding (the dwarf variety seems to reseed a bit less prolifically than the taller varieties). This year, I have many plants of various sizes, from 6 inches to about 2 feet tall, all of which have been blooming for the past month or more - however, I have one plant which has a huge healthy central stalk, numerous strong healthy branches, and not only no flowers, but not a single flower bud. It is about 2 1/2 feet tall by now, less than a foot from other cosmos which have been blooming for weeks. I would say that the central stalk on the non-blooming cosmos is nearing 2 inches in diameter, and is practically becoming woody. Since we sometimes have a killing frost in mid-September, I'm starting to think that I won't see a single flower off that plant. Has anyone else had that kind of a cosmos experience?
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After composting and soil improvement in my yard for the past 25 years I can't grow cosmos either, my soil is too rich. Cosmos prefer poor soil to bloom well- but I bet you have a ton of pretty foliage.
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I don't have the answer, but I got a cosmos just like the one you describe in a batch I bought on closeout from a garden center. All the others in the pack grew nicely. The one just turned into a huge bushy weed. I noticed it seemed a bit hairier than the ones that flowered, though the leaves were similar enough.
I pulled it out to give the others more room.
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however,
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I've had the same experience. One year I had cosmos plants that grew huge but wouldn't flower. I tried adding flower fertilizer, Potassium something I think it was, and breaking off the roots near the plant, but they would not bloom.
I agree with the idea that the soil is too rich. When I first started my garden and the soil was poor, cosmos flowered well. Now my soil is enriched. However, the year mine wouldn't flower, I looked around the city and saw other gardens in which the cosmos was flowering poorly, so I'm not certain of my explanation, maybe it was just the weather.

however,
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I planted some a few years ago, they were great. I don't think they have ever rebloomed. My job ended June 30 and I've spent more time in the gardens this summer, and I have a ton of little plants, all 12" or less, and no blooms. I purposely didn't weed them out thinking I'd have a mass of colorful blooms this summer.
We do have good soil but that doesn't explain why they bloomed the first year and never again, does it?
Diane Zone 6
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No it doesn't, but I believe the original poster and I had large plants that wouldn't bloom, a different mystery.

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Diane, cosmos are annuals, so I wouldn't expect them to rebloom - only to self-sow themselves so that a new generation could bloom the following year. I'm wondering how you have little seedlings around if the cosmos hasn't bloomed the past few years....

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Damned if I know! Maybe I should take a pic. But they sure loke like little Cosmos plants. I thought it was my moonbeam spreading *way* out but they are a bit different. I think I have the good camera with me so I'll grab a pic and send you the link later.
Thanks!
Diane
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OK, here's the foliage, anyone?
http://old-homes.net/pix/ours/flowers03/IMG_1040.jpg
Thanks!
Diane
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The pic could be cosmos foliage - it's hard to tell with the ends weighted down with water. I suppose it's possible that some seeds survived underground for several years and germinated when the soil was disturbed, although I wouldn't normally think of cosmos seeds as being that persistent. (Usually hard-coated seeds like grains and beans seem to have a longer "shelf-life".) There are a few other plants with very fine thread-like foliage, including nigella. Have you ever planted that? (Just thinking out lout).
anyone?

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No, it doesn't sound or look familiar. Sorry, I didn't think about the water. That area gets full souther sun against a white house and my dryer vents nearby. However last winter was pretty hard and I almost lost all my roses, so I would be surprised as well if they lasted
Considering it's September I guess I'll rip them out and plant real ones next year. I really liked them.
Oh, I do have a Coreopsis Moonbeam nearby but it doesn't look *quite* the same as that.
Thanks,
Diane
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opined:

Are you sure this is not threadleaf coreopsis?
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I do have moonbeam in the same area but it's a *little* different. Do they spread seeds? The main plant still comes up in the same place. If it is coreopsis, would reseeds not rebloom?
Thanks,
Diane
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opined:

Any plant has the ability to re-seed, if it makes seeds. Since 'Moonbeam' is a hybrid, it may have re-seeded, but did not have the characteristics of the 'Moonbeam.'
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Thanks! Since my issue is apparently not cosmos-related, I'll bow out of this thread. And I'll plant more cosmos next year as well. :)
Diane
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You've got horsetail.
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snipped-for-privacy@hotmail.com (Pen) wrote:

Horsetail? The pic I posted is horsetail?
http://old-homes.net/pix/ours/flowers03/IMG_1040.jpg
I really should take another.
Anyway, it never gets more than 6" tall and is only in this one garden (and has been).
When pulling some today I notices the bottoms of the stems were usually black.
I'll take some pix and start another thread.
Thanks!
Diane
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