Hi,
Can anyone suggest something to give/feed my cosmos to jump their growth? I really want bigger plants and the season is almost over!
I read that fertilizer isn't great because the nitrogen only encourages green growth.

Hi Diane,
Welcome to the National Garden Association forums.

I recommend Miracle-Gro Tomato Food for nearly everything. It is a water-soluble formula that you can apply as a foliar feed, a drench, or pour it around on the ground. It is reasonably complete and has more Magnesium than most complete formulas. I use it for my zinnias and my son uses it for tomatoes, (who knew?) egg plants, and peppers. As they say, use it according to the label. I dilute it one tablespoon per gallon for my zinnias. It comes with a little green plastic measuring spoon that provides the right amount for the "standard" garden watering can (a little over a tablespoon).

If I weren't already breeding zinnias, I probably would be breeding Cosmos. They come in a variety of colors, flower forms, and plant heights.

ZM (not associated with the Miracle-Gro company)

ZenMan said:Hi Diane,
Welcome to the National Garden Association forums.

I recommend Miracle-Gro Tomato Food for nearly everything. It is a water-soluble formula that you can apply as a foliar feed, a drench, or pour it around on the ground. It is reasonably complete and has more Magnesium than most complete formulas. I use it for my zinnias and my son uses it for tomatoes, (who knew?) egg plants, and peppers. As they say, use it according to the label. I dilute it one tablespoon per gallon for my zinnias. It comes with a little green plastic measuring spoon that provides the right amount for the "standard" garden watering can (a little over a tablespoon).

If I weren't already breeding zinnias, I probably would be breeding Cosmos. They come in a variety of colors, flower forms, and plant heights.

ZM (not associated with the Miracle-Gro company)

Thank you!!

I checked up the product and see the NPK is 18-18-21. Do you think this is too much nitrogen? Is it common to use a tomato/veg fert for flowers?

It's interesting, I thought cosmos were a popular plant, but so far, no other replies from people who plant them!
They are a wonderful plant and Think they are highly underrated. Very showy and easy to maintain.

I see many cosmos in Utah gardens. I usually use a little 10-10-10. It is good to improve the soil in the fall where you intend to grow annuals the following spring.

Hi Diane,

" checked up the product and see the NPK is 18-18-21. Do you think this is too much nitrogen? "

Not at all. That is a very evenly balanced NPK group. It also contains Magnesium, Copper, Iron, Manganese, and Zinc. All of those are vital elements that a plant cannot live without.

ZM

DianeD123, the labels on fertilizers designating them for particular plants are misleading. "For Roses" or "For Tomatoes" only means it is a good balance for those plants, but doesn't mean you can't use it on other things. You didn't post photos of your plants, so we don't know what other factors might be affecting growth—sun exposure, soil quality, watering routine, in pot or ground, etc. Whether you planted them from seeds or seedlings from the nursery, did you check the packet or label to see how big they get? Cosmos varieties range from very small to quite large.

Also, at this time of year nearly everything in the garden can use a nitrogen boost. It's the nutrient first and most likely to leech from the soil. Anything roughly balanced as described above will do.

@nmoasis
I'm attaching some photos of my backyard. I planted around the border to get some privacy, but as you can see, the ones at the right side are growing out of control and the left and middle need some help!
I suspect the grass fertilizer leaked there hence the huge stems and no flowers.
Nitrogen supposedly makes the greens big and little flowers.

I planted from seed, the pink, purple and white mix.
(It's my first year planting and I made the mistake of overseeding so they are very close together)
I really want to get the other side growing and give it a boost!

Dianed123, you did overplant. Miracle-Gro also makes a Bloom Booster fertilizer. I have used it for heavy bloomers in the past after it was recommended to me from a nursery owner here in NJ. His plants always looked better than everyone else's. It is 10-52-10.
We had a member at our community garden plant a mix like yours very close too. Maybe it is the same mix. His grew very tall, like 6 or 7 feet, maybe more. His were in a raised box filled with compost but it was only 2' x 8'. They turned out to be fall blooming plants. They bloomed a lot once they started and bloomed until frost. They reseeded every year until we pulled them out as they would flop and block the pathways.

Diane, You certainly had success growing those from seed! Yes, nitrogen does stimulate green growth, but many lawn fertilizers are especially high in nitrogen and/or formulated specifically for green, lush grass. So if it washed into the bed on the right it would have the same effect on those cosmos. I'm also looking at the soil there and wondering if it is better (richer, loamier) than the strip along the fence, which might have previously been grass (?). That can make a big difference.

Did you use the same seeds for all beds? There is such a sharp sudden difference in the height of the plants it makes me wonder if they are two different varieties. Dwarf cosmos grow about 18-24 inches, regular ones up to 72 inches. Overcrowding will stunt growth, because there are too many roots beneath the soil competing for the nutrients and the plants above are all competing for air and sunlight and room to spread out. I would thin both patches by one-third to one-half. Also, if you have humid, damp weather, overcrowding is an invitation to fungus and mildew. The roots are are too close to pull them up, so use garden clippers and cut them off at the base. I know it sounds contradictory that you'll get more flowers with fewer plants, but it's true. (Plus I know it's hard to do, mentally, after you grew them all from seed. Ouch ) All of them will be happier and healthier with more room. Then go ahead and use whatever balanced fertilizer you decide on. I hope they give you lots of flowers.

I was wondering that too. Did you plant two different types or did you plant one later than the other? I would also try to thin it down, but by cutting because you are going to disrupt the roots. The only thing is, they will probably start to flop so I would experiment a little.
Also, I would throw down a little compost in between. If I remember right, cosmos will root along the stems so if you mound up just a little compost it should be OK.
When did you plant the seeds? We had a cold start this year. I have cosmos I planted in early June from seed. It was cupcake and they aren't blooming yet either. Sonata self seeders just started blooming. They are smaller. Ladybird cosmos which are the yellow/orange/reddish short type came into bloom pretty quickly.

@nmoasis
Thank you so much for your replies! Again I am a newbie and really had no idea what I was doing.
I ordered my mix from American Meadows, they aren't dwarf, all of the same seeds.

A long story but will make it short. I planted my first batch at the left side on June 15. I had absolutely no idea what I was doing and before I knew it, I scattered the entire pack (1/4 pound) only at the left side of the fence.
I had to reorder more seeds and planted the back and right side a week later.


They were packed in there at the left but I couldn't get myself to pull them all out until a month later when I realized I'm not going to see flowers if I wouldn't do it. So I pulled out the entire bed and transplanted the bigger ones back in some new topsoil.

The ones at the right that are huge was actually the second batch of planting on June 22rd!

I had another mishap when the grass weed killer also got on the edge of the bed and I had to pull out a decent amount and transplanted from some more grounded areas to the front.

@lorettaNJ I would love to see your cupcakes! Can you show me what they look like at this point?
I was actually wondering why it was rooting at the bottom of the stem. Why is that? I thought I did something wrong there.

So at the end of the day... should I just pull or cut at the bottom to get these guys healthier? I probably already messed with their root system.

I'm attaching some of the pics of the original overcrowding, LOL.

The good news is that it was a great learning experience and can't wait until next year to grow them again properly.

Diane, What fun you've had! According to the American Meadows seed site, 1/4 pound of their cosmos seeds covers almost 1000 square feet.

So just press on and thin them. Cut them at the base, no pulling. Do you still have the seed packet? All seeds come with planting instructions, it will say "plant seeds x inches apart" or "thin seedlings to x inches apart." That's how far apart they should have been, so thin them accordingly. They'll be fine!

@LorettaNJ, I'd never heard of cosmos rooting along the stems so I looked for it. Found only two references, one from a home gardener and this...I don't know how reliable this website is, but thought you might be interested.
https://www.melindamyers.com/a...

Well I'm sure these cosmos didn't have aster yellows. But before I go any further, I'll take pictures of the cupcakes tomorrow. They're not blooming yet and they're going to look lonely compared to these. I did buy a lot of Cosmos seeds this year but I didn't get many started. If I can find some old pictures of those tall closely planted Cosmos, I'll post them here. The stems were huge by the end of the season.

@nmoasis, yes I did have fun! But ended up being so much more work than necessary because of all of the mistakes.

I read the instructions on the packet. But since it was wildflowers, it didn't say how far to plant them apart, rather just scatter by hand. So before I knew it, the entire pack was gone

I don't think anything is wrong with my cosmos that rooted at the bottom. I'll upload a pic of them tomorrow.

@lorettaNJ can't wait to see your cupcakes! I really want to plant those next year. I only saw those after I planted the typical pink purple white pack.

The cupcakes are only in bud. I planted them last year and didn't get any cupcake forms as pictured. I tried another supplier this year and planted what was left from last year. They have better conditions so we'll see what comes out of it. I think I ended up with seven or eight plants.

Oh and the cosmos do root where they are near the ground. Both the yellow/orange/reddish type and the pink, purple and white type. I didn't get a picture. Also, if you search, people root cosmos from cuttings.

Good to know, thanks!

@LorettaNJ such fantastic growth and a great stem! I wish mine all looked like that
Well, better luck next year, I won't give up.
Would love a pic of the cupcake when it flowers (and a recommendation of where to buy!)

One of the buds on cupcake colored up. Will it or won't it be a cupcake?