Non-flowering Cosmos

A certain number of the yellow cosmos I plant come up with huge shaggy leaves and thick stems but never produce a single flower. This is true of those I purchase in sets and those I plant from seed.
Last year I left them in assuming they'd eventually bloom, but they didn't. This year I yanked them.
What's the explanation? --Jenny
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I would imagine you yanked them because you are impatient and impetuous and you always expect instant gratification!!!
Try taking it easy and don't give yourself a stroke!!

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Jenny wrote:

I've got Cosmos sulphureus "Bright Lights" in several spots with a couple of ragweed plants growing up among them, which I only just recently noticed when they outstripped the cosmos in height while failing to produce any flowers. The foliage is pretty similar--are you sure it's all cosmos you're looking at?
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DrLith wrote:

Mine are also Bright Lights and yes, they do look a lot like Ragweed, though the seedlings are subtly different.
When I was young I had an extreme allergy to ragweed that would cause my windpipe to close if I were in a field of it. So I am pretty good at identifying it and I pluck out the seedlings I find in my yard as soon as I see them.
But beyond that, last year I left the one non-flowering cosmos that I had bought at a nursery until near frost and it not only didn't put out cosmos flowers, it also did not grow the characteristic ragweed flower. So I'm pretty certain it wasn't ragweed.
It's not a big issue, between the ones I planted and the volunteers from the previous year, I'm all set for flowering cosmos. I was just curious what might be going on. --Jenny
http://www.geocities.com/lottadata4u/ Type 2 Diabetes info http://www.geocities.com/jenny_the_bean/ Low Carb info
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The first thought that comes to mind is whether they get at least 6 hours of sun/day. But you probably already considered that factor.
Suzy O

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I get a lot of self-seeding cosmos, and some started to bloom around July 1 - others have yet to bloom - in many cases, the plants are within 2-3 feet of the others in nearly identical soil/water conditions. I have to assume that there are genetic factors involved as well as the usual suspects - light and/or heat triggers.

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The same happened to me this year. I raised about 20 cosmos from seed, and maybe two or three did not bloom at all, but where becoming larger than the others (thicker stems and much taller). They were grown besides flowering cosmos, so probably a genetic thing.
Good to hear I not the only person with these mutants in my garden. :-)
Cheers,
-- Storm

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Too much fertilizer.
Storm wrote:

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our cosmos, raised from seed, have been particularly poor this year
They go in the front garden in full sun (when it's out..!!) Howeve this year the show has been mostly flowerless
-- dotCompost
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In article snipped-for-privacy@gardenbanter.co.uk says...

I get a lot of cosmos in a first year wildflower seed planting. I think they dominate because there are no perennials around taking up space. Anyway, I've noticed cosmos blooming in all different stages of the summer season here in zone 5 Chicago. Some plants bloom early and often in June while others wait till July, August, and September. I have noticed that for some reason some cosmos just grow into a big bush with lots of foliage. These usually bloom late September, early to mid October. I actually prefer this type of cosmos because the foliage makes for a nice accent to my gardens and in general, I'm kind of bored with the cosmos flower and after they flower they get all spindly and ugly looking. Many times patience pays off and its nice to have things still going when fall weather arrives. My latest bloomer is Pineapple sage and if the weather cooperates, that won't bloom till November. If the weather doesn't cooperate it never blooms at all and I just grew a huge green bush all year. No big deal though. IMHO, green and big is good too.
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Mark Anderson wrote:

Well, if these big cosmos only bloom in Late September or early October, I'm glad I yanked them. We get our first frost so early here that they would barely begin to make a show.
And besides, I need that bed space for my ice pansies!
--
--Jenny

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