I'd like to see that! 6 feet is way more than any cosmos I've ever witnessed.

I imagine there might be patches of soil that are much richer than others - or maybe it's near another area that's getting fertilized? Conversely, there might be areas where the soil is depleted or contains something that interferes with nutrient absorption?

i doubt the size of the seed makes any difference.. but the genetics inside the seed will ...

are you actually getting the same golden cosmo from the seed???

in other words.. do they come true from seed .. if not ... then its genetics ....

any chance at some pics???

ken

I guess I should be saving seeds from the giant plants, separately. I've been trimming them off early, before the seeds mature.

I guess I should be saving seeds from the giant plants, separately.

==>> that would be one way to try to control the genetics ... but even then.. you might still get the random results ... but it should favor that tall ones ...

the only way to be in total control .. is to buy new seed every season .. of a named variety.. from a quality vendor .. predictability is the whole point of buying named varieties ....

but then.. whats the fun in that .. lol

ken

Genetics. Did you happen to mix two different species? I have both Cosmos sulphureus and Cosmos bipinnatus. The seeds are indistinguishable without careful inspection, but they don't cross-breed. I collect separately and store in separate envelopes.

Sulphureus are short. Colors vary (yellow, yellow-orange, orange-red), but mine over time have turned fire engine red with orange streaks as that's the direction I've been pushing them over the years. I don't favor any specific height so they tend to be about a foot in extremely rich soil.

Bipinattus are tall and can certainly hit four to six feet in rich soil and well-fed for some cultivars. My own "Bright Lights" variant after some (decades of) breeding in my own gardens is a bit taller than when it started out. I tend to favor the taller plants because they produce more seed. Colors are yellow, orange, and red, but over time I've bred the reds out and favored the yellow, yellow-orange, and orange as the red is covered by the shorter ones and I took out the ruddiest plants.

(addendum) There's also Cosmos pacificus, which will crossbreed with some difficulty with the sulphureus, I forgot about that one. So that could be a factor, too. Those get up to about 8 feet tall under optimal conditions and usually pink, magenta, or a pale purple. I haven't seen them in years and don't use them, they're too tall for my gardens and I don't like the branchiness of the plant anyway even if I forced them to dwarf. I'm not familiar with the crossbreed results as I've never done it.

I'd have to poke deeper if you're sure you only have one species. Dahlia have so many chromosomal copies that they can express a huge variety of heights, habits, and flower colors and sizes in one plant. Breeding there can be unpredictable, but collection on the cosmos has always been very linear, so I don't think that's the issue. But I'm not a hundred percent sure.

Thanks, everyone! Very helpful.

All my Golden Cosmos seeds/plants have come from one small plant I bought years ago. I am a sloppy seed collector/storer so I have planted older and newer seeds indiscriminately (and still wonder if age matters with this plant).

My Tropical Milkweed - which shares the same planting bed - grows to extreme sizes or stays small, so maybe it is the bed. Some areas have builder's concrete rubble and/or roots closer to the surface than other areas.

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In website of Lady Bird Johnson Wildflower center : "Cosmos has been so intensively hybridized.... Hybrids do not breed true from seed, so the seeds... may have none of the characteristics you may expect"

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Irma, about your Cosmos : How long does any flower usually last, (at least somewhat fresh state)? During which months do plants flower? Do butterflies frequently drink from them?

A golden cosmos flower lasts 2-3 days (I guess).

I start seeds outdoors in containers after "cold" FL weather, so from March on, I guess. A neighbor direct-sowed a bunch much earlier, in a deep mulch/composted long hill, full sun, and they were 2-3 feet tall very quickly... eventually they all turned brown together. They do seem to have a definite life span.

I guess by May mine are blooming, but the first plants to bloom are small as are the flowers. As the summer progresses and the rains finally come (July or August) the plants get their largest size. In July the first garden batch expired; they were 2-3 feet tall, don't know exactly how old they were. I guess they will bloom until the weather cools in December, but I think they will not be as tall and robust by then.

I'd love to try a red or red-ish version, is anyone has seeds.

I will send golden seeds to anyone who asks.

Oh, and about the butterfly question: no, butterflies ignore it. UPDATE next day: first Monarch or Queen I have seen in a couple of months TODAY was sipping on the cosmos flowers. Perhaps because the nearby Tropical Milkweed is currently flowerless.

Hey Irma

I just wanted to stop in and say Hello, even though I don't know if I can help with your question.

Several years ago, you sent me some of your orange cosmos seeds and I planted them in the cul-de-sac garden across the street from me. They grew and bloomed profusely and now they come back every year.

About the same time, someone else sent me a pack of "Bright Lights" and only one germinated and lived. I planted it in my backyard, where it grew to 6' and looked like a dang tree. I really thought I had mislabeled and since it didn't bloom for 7 months, I figured it wasn't a cosmos at all. The foliage didn't look like the foliage of the ones you gave me.

But then it bloomed and the flowers look exactly like cosmos across the street even though the leaves and stems and growth patterns are different. So I figured I have two different cosmos varieties, like Morpheus says. However, that doesn't offer any help to your conundrum. Except that the plants in both beds have been coming back year after year the same as the originals that were planted. In other words, my back yard garden only grows the super tall Bright Lights cosmos and the cul-de-sac garden cosmos are the short, thin-branched ones, which get about 4'.

Wow, SusieQ, that is very interesting!!!