Return to the Cottage Garden Forum | Post a Follow-Up

Should I whack my Cosmos?

Posted by oakleyok OK z7 (My Page) on
Fri, Jun 25, 10 at 8:50

Remember how excited I was about growing these? I rue the day I planted them. lol.

I do have the other kind growing, the more "feathery" one's with pink flowers. I'll definitely plant them again.

Here's 2 pictures of the yellow Cosmos. In the beginning they were full of blooms, now they're mostly green bushy monsters in the garden.

I don't fertilize as was told, I don't over water them either. I let them dry out as much as I can.

No clue what's wrong.

If I cut them back will they start over and bloom for me?

One side of the garden:


The other side of the garden:


Follow-Up Postings:

RE: Should I whack my Cosmos?

There are all different types of cosmos. Some have grown to 10' tall for me! Do you know what kind you planted?

RE: Should I whack my Cosmos?

I have no idea of the specific name except that these Cosmos only come in yellow or orange. No other colors.

You can tell by the thickness of the leaves they're different from the "lighter" cosmos...the one's that are more fernlike, which is what I thought I was growing!

This is what I get from buying a plant that's not specifically labeled! grrrr.

Don't get me wrong, they were really nice a few weeks ago, now they're just an ugly bush with very few flowers. And I religiously deadhead them too.

RE: Should I whack my Cosmos?

they might be in a "resting" mode, getting ready to bloom again. Many flowers do that. I wouldn't hold off watering them though.

I pinch out the spent bloom from time to time and water mine every other day. They have been non-stop blooming, but the plants are not nearly as big as yours.

Here is a pic of mine taken June 20th:
Image and video hosting by TinyPic

Did you put any potting soil mixture in there that contains fertilizer? Most fertilizers and soil mixes with fertilizer are for growing healthy green leaves, unless they specify for producing flowers. MiracleGrow, for instance, is a great leaf making fertilizer, but it does little for making flowers. It is good for giving plants a mid-season shot in the arm, so to speak, when the weather is hot, or if I see leaves on my roses turning yellow and the plants defoliating. It helps them to recover, but you MUST continue to water, not matter what. If there is fertilizer in your soil mix, you MUST water or it will burn up your soil and your plants. I'm being redundant here to emphasize my point. ;)

I don't feed my flowers anything but compost. I add a LITTLE composted manure around my roses in the fall every year or two, and side-dress them with my homemade compost when I have enough made, usually in midsummer when they need a boost, but that is it. The nearby flowers benefit from the side-dressings I give my roses, but I do not give the other plants anything but good old H2O. I have to water every day here.

Your yellow Cosmos seems to be a different variety than mine. Mine came in a Meadow-in-a-can mix, so I have no idea what variety it is. It is light and airy and I like that. I can save you some seeds if you want some for next year. You'll never need to plant them again, and they transplant easily too, so you can spread them around.

(Yah, I really like the Sensation variety too - pinks, reds and whites).

I definitely would WATER yours from time to time and then hide and watch. They will soon start blooming for you again. Those are tough little plants.

So...where have you been young lady? Eh?
I was beginning to think you gone to the barn and the cows ate you! (old California pioneers joke) :)

Your big sister,

RE: Should I whack my Cosmos?

  • Posted by natal Louisiana 8b (My Page) on
    Fri, Jun 25, 10 at 13:11

Yours are most likely Cosmos sulphureus. The pink/white/red combo is Cosmos bipinnatus.

This article suggests cutting back to 12-18 inches.


Here is a link that might be useful: Cosmos sulphureus

RE: Should I whack my Cosmos?

Annie, they were planted in regular soil, no potting soil added.

We also have a ton of these growing near our road in our wildflower plot, so I won't need any seed for years. lol.

Oh Annie, you should see our tall Blanket flowers! They're beautiful and growing almost as tall as the Cosmos!

Next year I'll plant the "common cosmo" though. Orange is just not a good color for me for some reason.

Natal, that's funny, the first link you gave me is one I have in my Fave places and read it again today, but I overlooked the part that said to cut them back! lol.

They'll be getting a whacking tonight if I don't see many buds. There's still a few but not much to make a difference.

RE: Should I whack my Cosmos?

It's funny, I think I planted the same exact cosmos!!!!! And I also planted the more traditional, feathery leaved ones. And I, as well, will not plant these orange/thicker leaved ones again.

It just showed the flowers on the seed packet so I didn't know I'd end up with these huge leafed things. I much prefer the traditional feathery ones myself. It's just funny because I have the same exact situation.

RE: Should I whack my Cosmos?

You know, I love them both and always grow them both - the pink/white ones go in my butterfly garden and front borders and I use the 'Bright Lights' orange/yellow ones in the hot color beds out back. Mine look rather like the pics you post this year as well - but when it gets hot and dry and they stress some they will really bloom their hearts out - and I find the seeds drop and I get a whole new crop of fresh blooming plants by late summer. Love them. :)

RE: Should I whack my Cosmos?

cindysunshine (what a cute ID),

Maybe that's why mine is blooming so well - everything gets stressed out in my garden. It's always dry. :(

RE: Should I whack my Cosmos?

Sometimes your doing something right without knowing it. My sister
planted some mixed Cosmos seeds where I had a pool filled in. I'm
too busy with my flowers and vegetables, that I hardly ever water her
flowers. The Cosmos are doing great in all different colors. There's
another yellow flower seed she threw in there. It's very pretty, but I
don't know what the flower is. I'll take a picture of it today, so you
can identify it. I believe it's a wild flower. Will try to save seeds from it.

RE: Should I whack my Cosmos?

Kry, that's funny! I was SOOOO looking forward to growing my first Cosmos this year.

I ended up cutting them back about 18 inches and they look a lot nicer.

These Cosmos are better grown near a fence as a backdrop.

But the other Cosmos, the more delicate one's you and I like, I'll be planting a lot of them next Spring!

These orange Cosmos I planted as plants. The other Cosmos I planted as seed (not a lot, darn it!), they came up so fast, and they're so pretty. I'll be growing a lot more of them next year for sure. I usually hate planting seeds for fear they won't come up, but the "common" Cosmos did great!

Roper, definitely send a picture!

RE: Should I whack my Cosmos?

That's so funny because that's the same exact reason I hate planting seeds...I have this fear they won't come up and THEN what will i do????????

I have found though that cosmos are incredibly easy from seed...I literally throw them on the ground and don't even cover them and up they go!!!!!!!

I also love them because you don't have to fuss too much with spacing...just throw them down and they'll grow, 1 mm apart or an inch apart!

RE: Should I whack my Cosmos?

Thank you, unknown people! I'm a-goin' out to get whacking! :D

 o Post a Follow-Up

Please Note: Only registered members are able to post messages to this forum.

    If you are a member, please log in.

    If you aren't yet a member, join now!

Return to the Cottage Garden Forum

Information about Posting

  • You must be logged in to post a message. Once you are logged in, a posting window will appear at the bottom of the messages. If you are not a member, please register for an account.
  • Please review our Rules of Play before posting.
  • Posting is a two-step process. Once you have composed your message, you will be taken to the preview page. You will then have a chance to review your post, make changes and upload photos.
  • After posting your message, you may need to refresh the forum page in order to see it.
  • Before posting copyrighted material, please read about Copyright and Fair Use.
  • We have a strict no-advertising policy!
  • If you would like to practice posting or uploading photos, please visit our Test forum.
  • If you need assistance, please Contact Us and we will be happy to help.

Learn more about in-text links on this page here