Frillylily said:if that is the case it means I planted all these seeds and didn't get even one to actually sprout. It has been 10 years since I've grown them but was so sure it was them when they started sprouting.

Well I wouldn't give up on them yet, if they're ragweed they'll flower eventually and the references I looked at seemed rather inconsistent about the foliage arrangement. I've had problems in the past with Cosmos bipinnatus not flowering, but I've always acquired C. sulphureus as already blooming plants so there was no question of their identity.

I still think they are far too handsome to be ragweed.

I usually don't bet, but in this case my bet still goes with cosmos. Along with all the self-seeded cosmos sulphureus I let grow on my property, I also let some grow in a pot with my plumeria. Here are pictures and it shows hairy stems. These are at least a foot or more tall and have not bloomed yet. As a matter of fact, I have one cosmos sulphureus plant that is blooming and it is about 2 feet tall, but I have a lot of others that size that have not bloomed yet.




One problem I see is that if it is cosmos sulphureus, they may be too close together. I would thin them to one plant every foot. If they get to be 6 feet tall like mine do, they may overshadow those zinnias.

I've had Cosmos sulphureus, (many years ago,) which grew into like some monster sized, giant form !
Like, about, over six feet tall. I'm being quite serious, here...

The seeds were in a packet (which were included, for free,) & have since forgotten, with just exactly what it was, they had been distributed with...It was so very long ago.

You might try to research that. About others too, that also had similar experience, & had grown these giant sized, Cosmos.
Perhaps may be some images you might locate or past discussions about the very subject, as a topic. (Quite possibly, with images of them.)

I don't know, if was a result of some sort of an experimental attempt, at hybridization. Or quite what, was the cause. As I do think I may recall, I wasn't the only one, & others had even taller ones.

We also had Cosmos sulphureus grow over 6' tall at our community garden and bloom later in the season and we had the shorter ones grow 2 or 3 feet tall, bloom earlier. You did plant the seeds so wait it out. Ants can move seeds around.
I have pulled out flowers assuming they were mugwort and we had members grow beautiful tall, mugworts, insisting they were not weeds. You can always look at your surroundings along the wood edges and roadsides, see what is growing there and compare.

okay well here are pics of the ones I grew before-10 years ago. They never got over 12-18 inches tall at the most. Maybe I bought the wrong kind? Is there a variety that looks like this, self seeds like a weed on drugs and blooms like crazy all summer? They were thinish, wispy and airy, not a thick heavy plant. That's how mine did for the 14 years I lived there.
But the leaves of what I have now do look like what I remembered, just that they are much larger.

The "giant" form, of the Cosmos doesn't usually even begin to flower, until well towards Autumn.
(Some, may have rather large blooms, too.)

I'd allowed them to grow, to eventually see what they'd ever do, & had some difficuly with even producing the flowers.

There may even probably be (a rather, quite old) post here, that specifically mentions these in one Forum, about these Cosmos.
Strange as they are.

In 2009, July 4, in the plant I.D. Forum, a question was asked. Something to the effect, as titled; "giant tree size Cosmo has me perplexed." (Thread was Closed, as apparently, was "solved.")

Look at the Fifth post, for an image of size of one Cosmos sulphureus bloom, & comments made in the Post, to that Thread.

Showing much larger size of the flower, of the C. sulphureus, & comment of just how tall the future generations of plants, sown from those seeds, were growing.
(I had to use Google, as apparently attempting to "search", in Plant I.D. Forum, at garden.org doesn't extend that far back, in time.)

Frillylily, those pictures from 10 years ago look like cosmos sulphureus, but there is a 'Cosmic Orange' that is supposed to be short. I don't grow that one, so am not quite sure of the coloring on it. The database here does not list a height, but here is a link to a site that has more detail. Maybe that is what you had?
https://georgeweigel.net/plant...

Shawn, that reference comes from Dave's Garden, not NGA. Dave Whitinger used to own Dave's Garden back then, but sold it and started up NGA (previously known as All Things Plants) in July 2011, so you won't find any threads before that on here. Here's the thread you referenced:
https://davesgarden.com/commun...

My Cosmos Sulphureus Bright Lights blend. Lush, healthy foliage, hairy stalks, not blooming yet, only one plant out of several has buds.

Remember, the more you water them, the later they'll bloom.

Thank you for correction of my error, Vickie.
Also, for providing link, too.
I'm just rather over tired, & wasn't paying close enough attention to have noticed, that it had been posted at Dave's Garden.

(There is also, a very similar post, in Garden Web/ Houzz Forum, from long ago, too. About similar topic, with image. Plus, even in a Blog, too.)

While I've actually grown this gigantic form of Cosmos (suplhureus ?) before. Which tends to flower much later in Autumn.

I've also grown a Cosmos, what in Asia is called "Ulam Raja", (which can grow tall like a huge weed, for "greens".) Not sure that's quite the same as caudatus species, or not...

What I don't know, is if it has origins from a wild species , or is a hybrid instead, (be it, intentional, or otherwise,) & may have crossed with some other closely related species, & then soon becomes stabilized.

I do know those older, 'Cosmic', & 'Klondike' (or Klondyke ?) series, were produced, & bred for shorter sized plants.

(I'd grown 'Early Sensation', or something similar seed cv. of bipinnatus, some half century ago. Flowered, about, only 6 inches tall...)

Perhaps these huge growing, much later flowering types, started to "revert," back towards original heights, & form.

I just don't really know, for certain, about the origins, & yet I do happen to know, that they do exist.
There are even old Cosmos bipinnatus seed cvs. which were much taller varieties than usual, such as 'Lady Lenox', & mammoth.

(Edit, to correct another, error.)

Well, my Cosmos bright lights have buds on them and they're only around 6" tall! All the other Cosmos I've grown were various heights; iIve had them from 1.5' all the way to 6' tall.

I just thought was rather a "curiosity", to have grown it, so many years ago. As at first, I'd thought was a weed, & almost mistaken it for one, too.

While I think Luther Burbank had published a book, about 100 years ago. In it, had claimed he'd hybridized, (what is often called the "Chocolate Cosmos,") or Cosmos atrosanguineus, into both a white, & pink flowered forms.

I can't verify, if true or not. While he apparently stated in print at least, as having done so, & having achieved those results.

While C. atrosanguineus isn't extinct in MX. & still grows wild there, in spite of what is so often repeated on internet as "truth", as no longer existing in the wild. While in fact, was never "extinct" there, & stil isn't...

While I'm fairly certain there were a number of older, annual type Cosmos varieties of which existed, long before I was ever around.
Those genetics may have still influenced, & contributed to much of what currently is a rather wider selection of seed grown cv's. available, nowadays.

It would be of some interest, to know just exactly how this "giant form of sulphureus," ever started, as in just how it ever arose.

all I've ever seen of sulphureus was rather short. I've never seen the giant one.

We have had cosmos at the Community Garden, both C sulphureus and C. bipinnatus grow as big as tall sunflowers.
I grew Ladybird from Swallowtail last year which was a nice short mix. I planted the seeds the beginning of June and they were in bloom by August. They did burn out before the end of the season. You can see they were the height of zinnia in the first picture. Bright Lights is supposed to also be3 to 4 feet, but I am almost certain those ended up being the tall ones over 6' that the other member planted. He did grossly overplant the seeds, so they had nowhere to go but up.

We've planted bright lights in one of our MG projects by the lake, but they never get tall there, probably because that's basically wildflower gardens and we don't ever fertilize and don't water very much in the summer.
Beautiful pics, Loretta!

I think it is who you buy the seeds from too. I feel some companies collect their own seed and sell them. Then the results aren't as stated.

Sounds about right.My bright light seeds were Burpee seeds. Although they get more expensive every year, I have found Burpees to have really good seed. I try to buy off the rack and not online because the racks are much cheaper.

The 'Bright Lights', is a rather old variety.
At times, some cultivars need to have what's often called "reselected", or have culled out, those that don't nearly grow anything closely resembling like, they used to.
That isn't to say, one possible rather very similar looking annual, is Cosmos caudatus. Which often has pink flowers, & the Asian form is rather "leafy", as that's just what it had intended to be grown for.

That isn't to say, wild species form, of some sulphureus, or bipinnatus aren't rather tall growing. (Or, had originated from some much older, taller, seed grown varieties.)

I'd simply much rather prefer to try growing again, these 'Back Magic' "Chocolate Cosmos," from seeds, instead. Which sprouted, 6, out 6. Not even listed in Database here, & in my "plant list," simply included under Cosmos atrisanguineus, (being, just a seed grown cultivar of it.)
At least is fragrant, with dark velvety blooms, & perennial in my Zone. As I do so happen to very much, enoy, & appreciate it.

Not, that if you prefer to be contented with, & happy or pleased with the taller huge forms of Cosmos. (As there certainly isn't anything wrong with doing so, as far as I'm concerned.)
I've grown many kinds of different Cosmos in my days, of over about half Century spent gardening. I had started actually, while even quite rather younger, at that..

As some just may really do enjoy those giant form Cosmos. Be it an older variety, some species, (reversion, or hybrid, ) of bipinnatus, or sulphureus.
I just think of them, as being part of a garden, to enjoy.

(I'll leave it at that, as I think the topic of I.D. has been discussed thoroughly enough, in adequate detail.)
Enjoy those Cosmos , & please have a safe, & Happy Fourth of July !

Grow both orange and yellow Cosmos ... seeds gifted by a Gentleman gardener down the road. Love the pollinators attracted to them ... just wish they didn't grow so tall [spouse thinks is looks junky -- told him it was a Cottage Garden - so far, he has bought it]