cosmos stubbornly refuses to bloom

[gregpresley]

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?

[Beecrofter]

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.

[Jenny]

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.

-- Jenny - Low Carbing for 5 years. Below goal for weight. Type 2 diabetes, hba1c 5.7 . Cut the carbs to respond to my email address!

[Andrew Ostrander]

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.

[Diane]

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

[Andrew Ostrander]

No it doesn't, but I believe the original poster and I had large plants that wouldn't bloom, a different mystery.

[gregpresley]

[Diane]

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

[Diane]

OK, here's the foliage, anyone?

Diane

[gregpresley]

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). "Diane" > OK, here's the foliage, anyone?

[Diane]

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

[escapee]

Are you sure this is not threadleaf coreopsis?

Need a good, cheap, knowledge expanding present for yourself or a friend?

[Diane]

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

[escapee]

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.'

Need a good, cheap, knowledge expanding present for yourself or a friend?

[Diane]

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

[Pen]

You've got horsetail.

[Diane]

Horsetail? The pic I posted is horsetail?

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