Most of mine are 3 to 4 feet, but I have one monster that is at least 6 feet and hasn't put on any buds yet. I don't know the variety (lost the marker), but all of mine were commercial seeds.

Karen, I have about 4 that are at least 6 feet tall, I was just looking at them today,and wondering what the heck was going on.I have never grown Cosmos,is this unusual?
cAROL

hi just1morehosta, nice to see your name again here at wtrsow forum! :D

I'm so glad you're back!!!

If they are growing tall I assume you are referring to the C. bipinnatus species. Mine are at about the 5' mark in one bed and 3-4' in another. The difference is that one bed is much more fertile.
These ones CAN get pretty tall depending on soil fertility, water and space. I do that it is suggested to not fertilize if you don't want mass foliage at the expense of flowering.

My mother had some at seven foot last year, they flowered well too. I have some at six foot but most were around four or five. It is interesting. I planted them all in the same sfgarden with the same soil. I did expect some height so at least they are next to the trellis and not in front of anything else.

I have one over 6' tall and just starting to bloom. Last year, I had many that tall that never bloomed. This year, my second round of scattered seeds are a little over 3' tall. They are blooming profusely though.

The ones I planted were Daydream and Candy Stripe from commercial seed, but many of them are whatever color they want to be. One bed that has them got a mixture of compost and horse manure, the other bed got nothing, but I think rain runoff may have washed some of the compost/manure into the bed I didn't add it to, since the only thing separating the beds really is a chain link fence, and the composted bed sits slightly higher than the one on the other side of the fence. Eh, anyway, my cosmos have done much better this year than last year, just wish I could say the same for the nicotiana. They grew great last year, this year nada.

Karen

I have a variety of heights as well and dang if I can tell what variety they all are!! I thought some were picotee but I think they are candy stripe.

Mine were all winter sown, traded seed.

I have noticed that the tallest/healthiest of my clumps is planted in basically sand.

A few of the tallest are also getting the withered looking foliage and new buds.

Last year I had some cosmos inexplicably grow to seven or eight feet. The seeds were from a sack of odds and ends leftover from years past so I have no idea as to the strain. Frost about mid to late October and no sign they ever intended to bloom. Out little city is built on an ancient sand dune and I was not fertilizing the area so they didn't get much nourishment.

Thank you Neil,
It is nice to be back.
I commented on one of the postings about your garden,lookS wonderful, congratulations,you have done an amazing job.
Did any of your hosta seed come up?
Not one of mine did.
I think i gathered them to late in the season, but this year,I will have a BUNCH!

All my cosmos came from the same pack,and are grown in the same soil.Interesting to say the least.
I think they are picotee.
So nice to see you all again.
cAROL

Nothing came up. I've read somewhere that hosta are really tough to grow from seed.

wEEELLLLLLLLLLLL,If you wanna try again,I will have many.
Sorry you went to all that trouble of WSing, and none came up.Bummer eh
cAROL

Minor hijack...
I LOVE THESE!! Cosmos "Dwarf Sonata Carmine" from Swallowtail Seeds. I didn't have enough to fill the bed, so the back half is carmine, and the front is 'bright lights' (or maybe it was polidor...can't remember)
They're only about 12" high, and I am going to use these a LOT next season, and definitely fill this bed (although I'm liking the Carmine/Orange combination)

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I am glad to know huge cosmos is normal! This is my first summer with them, I got a small plant from someone else, don't know the strain, one part is tiny and has had 3 flowers, the rest is massive stalks with no flowers.

Those short ones look nice. I like the looks of them better than the tall ones. I might just have to get seeds of those and grow the shorties instead of the tall ones for my daylily bed. They would look much nicer.

Karen

Love the look of the dwarf ones also,thanks for the pictures
cAROL

I grew the dwarf Sonata and they are about 3 1/2 feet tall. They did bloom a lot, but like most taller plants here, needed staked against the rain/wind. I did lose a few that were knocked over by the wind and rain. And I didn't feed them anything.

Several years ago I WSed one called "carpet cosmos", a yellow-gold-orange mix like ladybird. They reseed like crazy and they do stay small- about 18 inches. Pretty, but I can't allow so many next year.

Also, you can try pinching them when they're small, or simply give them a haircut if they get too big. They'll bloom again in a few weeks.

Karen

I have picotee cosmos growing in front of my porch, and they are easily 6' tall. I will have tons of seeds from these too, I have been collecting them since they started setting seed.

In another bed I have a variety of plain pink cosmos, Can't remember the name, but these started blooming much later than the picotee, and are even taller!

Jenny P

This is what I have

light purple cosmos - 5.5 to 6'
cosmos radiance - 4 ft
orange cosmos - 3-4 ft
cosmic orange - 1ft to 18 inches

Hey, did I post the follow-up? I'm SO going to plant these again and FILL the bed next year! This was just about peak on September 25. Color is nowhere near as vibrant as it was in person!

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Great pic. My cosmos are still going, the Gloria's got six or so foot. I have some that look like psych with the extra petals but not fully double in white, pink and such and they are at least six foot and have loads of buds higher up.
In this pic the trellis is five foot so you can see if they were straight how tall they would be.
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Here is a wider view.
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This is what I have so far(2 orange not yellow),couple more behind these but not blooming yet

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I have been forunate in the past two years to have received one called "Double Click' and another called "Ladybird". They were both just about 18 inches tall, but I wasn't able to save seeds. So this year I have trades that are just labelled 'Cosmos' so I expect they are the jumbos and I'll plant them near the back fence. My first encounter with Cosmos was in my gardening infancy when I took a few seeds from the Experimental Farm. I direct sowed them in my front border and they grew over six feet, fell over the front laneway, and had stems bigger than my thumb!! It was horrible and then I couldn't
get rid of them for years. Now I will place them in the right place. It strange how it seems amusing now.

LOL mine just sprouted, they are about an inch tall...LOL

This threw me for a loop because I didn't look at the date. LOL. Mine haven't sprouted yet since I sowed them this past week. Good to know they get so tall, though. I'll do the rest of the seeds in the back of the garden in between the hollyhocks.

I've got volunteers from last year's plants popping up. Let's see how big they get in 2010!

Karen

LOL, caryltoo. i did the same thing. I couldnt figure out how everyones were 6' tall already and mine were 2"
Tammy

I'm renewing/bumping this thread to ask if anyone knows how to encourage Cosmos to bloom more/earlier? I have a mix of wintersown and volunteers this year which got between 4' and 6' tall and bloomed OK through the summer. Now, however, when frost is about to arrive, they are blooming like CRAZY! Is it possible to get this kind of action earlier? I wonder if the nutrients from the leaves I use as mulch finally ran out. I also pulled out other annuals that were spent and cut down surrounding perennials that were worn out. Maybe more space/sun? My bed is not that crowded to start with. I'm letting it fill in as the perennials mature. I guess I could just be satisfied with what I have, but they are SO GORGEOUS! I'd love to have them like this when the rest of the garden is in full swing. Let me know if you have any other ideas. TIA.

Martha

I'm with docmom above bumping this again because Cosmos information is spotty on these forums.

Frost was threatening so I cut some large stalks of flowering cosmos and put them in a vase - and forgot about them.

Most of the leaves and flowers look dead but there are many roots on the stems in the vase. Some roots are six inches long and branching.

I am a tinkerer, as a kid I wanted to be an alchemist, as a student I once worked in research. Suggestions as to what next to do with my cosmos are now being solicited.

Mine are between 5-6ft.
Only fertilizer they got was composted chix manure and shredded leaves. They did well in the Ohio clay soil.

This past year was the first time I planted cosmos. I'm still new at starting things from seed and I had completely forgotten what I had planted. I was starting to 2nd guess myself. For the longest time I didn't know if it would ever bloom, it just kept becoming this giant plant with a stalk as big as my wrist. I kinda feel bad mowing part of it down with the mower, lol. I was about to rip it out when I noticed it was finally getting some buds. I'm glad I waited, the show in the fall was worth it.

Mine seemed to stretch for the sun, I had planted them in a border between some leyland cypress trees on the side of my property. They were watered fairly regularly once a week. Maybe a sunnier location will bring about blooms sooner?

I took these pictures a bit late in mid October. The fence is 5ft?

I think these are thumbnails that will open larger if you click on them.
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The cut flowers on the stems that I reported on Oct 24th above produced some viable seed. I've about six seedlings growing in a tiny pot in the window.

just1morehosta......Cosmos will produce more greenery than blooms if the soil is very fertile......I'll try to find a link to that info.

Wow! That's tall! Mine are around 3-4 feet tall. I have the single variety with burgundy/pink flowers and a double variety, with burgundy flowers. Don't know the names as they were given to me at a seed exchange.

Another recent thread here: Cosmos height -

Ours is about 10 feet tall! As it was the end of October and frost imminent it was cut down. Grown from a packet of seed of unknown origin, all produce very tall plants with many blooms. Even as it was cut down there were dozens of blooms left. Three pots with maybe 20 plants, amazing!

We grew ours from seed directly in the garden. We put fish fertilizer on the plants twice once they matured . They are mostly 7’ tall and flowering very well. We thought they were growing taller than usual but it has been a bunch of fun to watch them grow

One of my cosmos from a pet of seeds has grown to over 8ft.!!!! And has flowered

And about 10yrs ago a Sunflower grew to over 8ft in the exact spot !!

Some of my Cosmos are 8ft tall this year too. It took forever for them to flower though.

We got our seeds from the Dollar Tree.... and I just measured the tall one. I know nothing about them, but ours measured exactly 12 FEET TALL!!

??? A 12 ft Cosmos? lol Sounds more like a sunflower!

I had to see if others in the growing world were experiencing super tall and thick-stemmed Cosmos! In years past, I was accustomed to Sonata or Sensation Mix, those would grow to 2-3 feet and I thought that was 'normal'. I am not sure what variety we planted this spring, they bloomed in pink hues; but oh my gosh - 6 to 7 feet tall and THICK stalks, like cornstalks or sunflower stalks! did not fertilize at all. They also branched out like crazy and some got too heavy and broke.