BartJY
Full Member
Posts: 41
Joined: Fri May 20, 2016 6:47 pm

Cosmos troubles

Hi Folks,

My Cosmos don't seem to be doing very well.

I planted the seeds a little more than a month and a half ago. To date the tallest plant is about 8" tall and the smallest about 3". With all the others somewhere in between. Is this normal for them? I would have thought that by now they would have been much bigger. I've read that they like poor soil and are very drought resistant. With the recommendation being don't fertilize or water them. Well, I got poor soil. Mostly clay with some mulch on top. And as for watering, only when it rains. But, I have cheated twice and watered them because they looked like that were on their last legs.

So please, enlighten me. Is this normal for the buggers? What am I doing wrong or right and shouldn't they be two or three feet tall by now?

Thanks
Bart

nltaff
Senior Member
Posts: 142
Joined: Sun Apr 03, 2016 9:02 am
Location: Central NY (rural) Zone 5

Hi Bart, Where are you (zone or geo location)? Where are you trying to grow the cosmos (length of sun exposure)? Are the plants intact but merely small, or do they look like they are being eaten or affected by fungus or mold? Pictures might be helpful, along with info on the kinds of weather you've been having (rain frequency, overnight lows, etc.).

BartJY
Full Member
Posts: 41
Joined: Fri May 20, 2016 6:47 pm

I believe I'm in 7a. The plants are intact, just small. It's been dry. The plants are in a mixture of some potting mix and clay on top of clay. I've only watered them twice. Most of the time it's been dry. On average it's been 80s +/- and 60s at night.

Thanks
Bart

nltaff
Senior Member
Posts: 142
Joined: Sun Apr 03, 2016 9:02 am
Location: Central NY (rural) Zone 5

Bart, I've never fertilized cosmos, I've just stuck them in the ground and they grew. I've grown them in heavy clay soil where I used to live and I've grown them here in sandy, rocky, silty soil as well. I do think that for the length of time you've been growing them (about 6 weeks or so) they should look like the plants one would normally buy in a 6-pack. Whenever I've purchased them, they've been tall for 6-pack plants (6-8") just because that's their nature-tall and skinny. It is the point at which you are now in their growth that I've planted them in the ground and they usually take off. I'm not so sure about the advice on not watering however. The drought tolerant part certainly is true. They can be wilted and near dead-looking and they will bounce back with some water. My suggestion is to water them like you would any other annual and see if they don't begin to gain some of their intended height.

imafan26
Mod
Posts: 13961
Joined: Tue Jan 01, 2013 8:32 am
Location: Hawaii, zone 12a 587 ft elev.

If your pots are too small, they won't grow very much either.

nltaff
Senior Member
Posts: 142
Joined: Sun Apr 03, 2016 9:02 am
Location: Central NY (rural) Zone 5

An after-thought, check your seed packet to ensure you've planted full-sized cosmos. There are dwarf varieties that only grow a foot or two tall. Also, cosmos tend to self-sow and if your bird population doesn't take all the seed, you should end up with cosmos in the same site next year, sprouting up at an earlier date than when you planted them this year. I always liked to plant cosmos and cleome (a prolific self-sower, and curiously appealing flower) together. You might try snipping the spent flowers and dropping them at the foot of your existing plants for a while, before discarding them in the debris pile.

BartJY
Full Member
Posts: 41
Joined: Fri May 20, 2016 6:47 pm

Dwarf variety? Hum, that could be it. The seeds were given to me in a clear plastic packet. No description of what the variety is.



Return to “Flower Gardening & Garden Design”