Cosmos are annual flowers with colorful, daisy-like flowers that sit atop long, slender stems. Blooming throughout the summer months, they attract birds, bees, and butterflies to your garden. Growing easily from seeds, cosmos even survive in poor soil conditions! Here’s how to grow cosmos.
About Cosmos
Cosmos produce 3- to 5-inch daisy-like flowers in various colors, including pink, orange, red and yellow, white, and maroon. Their flowerheads may be bowl– or open cup–shaped. These beautiful plants can reach 6 feet tall.
Cosmos grow in both beds and containers—and they also make great cut flowers!
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Cosmos
I started my Cosmos indoors> I have put them in my greenhouse and also outdoors to Harden off . They seem to start out well but once about 3 or 4 inches tall the leaves begin to turn brown and die. I've lost several plants to this. Could it be over watering? They die from the bottom leaf set up.
Extending your Cosmos season
As a kid in Nova Scotia more than a few years back, I grew Cosmos in our back garden. After seeding direct into the garden, I watched as the young plants started to grow. As they began to flower, I chose one plant and picked off ALL the buds. That plat did not bloom all summer but it developed into a massive plant about 4 feet high with a stalk well over an inc in diameter. As the rest of the Cosmos reaced the end of their productive life, I let this giant finally bloom, and bloom it did. Surviving a number of frosts on its own, it showed off it colours well into December after all its garden mates were just a memory.
If you decide to try this, pick several of your plants to "debud" among the rest of your plants. You should end up with a long lastinf show of colour from these pretty and delicate looking beauties.
Good Luck!
Transplanting Seedlings
Are Cosmos stems adventitious like tomatoes? Can I bury the stems deeper when I transplant them?
Thanks!
white powder on soil and leaves
hi i have this now on my cosmos I planted in small planterbox. It's only a handful amount on the soil but I noticed beforehand 5-10 small white powdery on leaves of cosmos. Can I use Neem oil for this? I'm thinking it's a matter of powdery mildew fungus problem? Thanks by the way on responding on my previous inquiry.
cosmos in containers
Hi! how can I grow my cosmos to 5 ft tall if I will only plant them in rectangular plantboxes?
tall cosmos
Try these: yellow cosmos (Cosmos sulphureus), which can grow 4 to 7 feet tall.
seeds
I have orange cosmos here and they just grew in my front yard. They're beautiful. What stage of a spent bloom are the seeds in? When the heads and stems are still green and the petals have fallen? Or do I wait for the stems to turn brown and the heads are dry and I see spikes? They're not even shaped like "balls"; they look almost dead.
cosmos seeds
The botanical name for the orange variety is Cosmos sulphureus. Most cosmos varieties develop seedheads if you leave the faded flowers on the plants. The seedheads may look a little different—spiky—but you’ll be able to see and collect the seeds after they have dried.
The seeds are in the center of the flower. As the flower dries they start to separate and you can see them quite clearly about an eighth of an inch long. Let them dry right on the flower but make sure you get them as they start to open up and separate. Put the flowers into a paper bag and shake out the seeds.
There is a wealth of knowledge in the comments by editors and gardeners below. We invite you to peruse it.
Cosmos in pots at the end of the season
I have some lovely cosmos in a pot but now it's coming to the end of the season, I was wondering what I should do with it? I don't have a shed that I can store it in - will it still re-seed in the pot?
Reseeding Cosmos
Cosmos are aggressive reseeders, so it’s likely that you’ve got some seeds in the pot already. However, if the pot has had cosmos this year, you’re better off starting with fresh soil next year. This way, you won’t risk the continuation of pests and disease, and next year’s plants will have plenty of room and nutrients to help them grow their best.
To save seeds, watch for seedpods to develop on the plant and snip them off just before they a start to look dry. Keep these in a paper bag in a cool, dry place and spread the seeds once again in the spring.
Cosmos not seeding.
My cosmos bloom, but the seeds are too thin/tiny and weak. How to improve the seed grow for repotting? Also the stem are weak. How to strengthen the stem. Im leaving in Singapore is Singapore suitable for planting cosmos? There is one strong cosmos plant but not blooming. Should I cut it off?
Cosmos Problems
Lack of blooming could be caused by too much water, too little light, or too much fertilizer. We’re not personally familiar with the climate in Singapore, but if it’s too humid and wet, the cosmos may struggle. They prefer to be grown in well-draining soil in full sun.
Watering
How often and how much water should I water my cosmos plant and also how much soil should I use if I'm using 4" terra cotta pots and all-purpose soil? I'm doing an experiment for school and I need exact measurements.
Cosmos turning brown from the bottom up
My cosmos were during beautifully and the last few times I went out to dead head and water them I found several of the branches turning brown. I love these flowers and were so proud they are doing well up till now. Have watered them to much which I usually do daily cause it has been so hot and have fertilized them at least several times since planting them early this summer.
Need Help with Diseased Flowers
Hello, my daughters Cosmos have developed some sort of growth or disease - is this normal and can we get rid of it? They look like spikey legs growing on the stem. I have pictures but can’t upload them. My daughter grew these from seeds and they are beautiful - except this one. Please help. Thanks Bob
Spikey legs on stem of Cosmos
Since you could not provide a picture I'm not sure what you are looking at, but after the blossom dies off the blossom will be replaced by the seed heads which look like round "spikey balls" on the end of the branch. These spikey balls are made up of many seeds which can be easily harvested to be used for next year or they can be allowed to fall to the ground and reseed themselves.
Cosmos Seeds
"Where can I purchase Cosmos seeds. I'v checked local nurseries but they don't have them.
cosmos
Where can I buy cosmos seeds?
Cosmos Seeds
Try an online dealer, such as Burpee, Park Seed, or Territorial Seed Co.
Cosmos seeds
Dollar Tree when seeds were available
cosmos seeds
I bought mine here and am very happy! myseedneeds dot - com
PURCHASE OSMOS SEEDS
I got mine from Wilkinson's for about £1/2
Cosmos seeds
Go to American Meadows. I have liked everything I have purchased
Cosmos seeds
I would like to purchase cosmos seeds--variety of colors & some that do not grow really tall--Thank you!
Cosmos,Colors and Sizes
How to Plant and Grow
Looking for cosmos seeds
I am looking for cosmos seeds . Where can I get different coloured cosmos flower seeds.....Looking forward
Cosmos
Next to wild white Daisies with the yellow eye, Cosmos are a favorite. I too have a sandwich bag of Cosmo seeds. I am excited to get winter over so i can get the seeds growing. Thank you for the information. My question is," can i mix wild daisies in the same garden with the Cosmos?" Thanks again.
What plant to pair with Cosmos
This advice is too late for you, but hope it helps others. We’d sow our cosmos seeds in March or April. Harden off the seedlings before planting out in a sunny spot. Many flowers mix well with cosmos. We haven’t tried daisies but I’m sure they’d grow. It depends on the color of the cosmos. Against a white daisy, we probably would not pick a white cosmos; it would be better to have a deep magenta cosmos. However, it’s a personal preference!
cosmo seeds
i have a sandwich bag full cosmo seeds. plz sumone tell me how many seeds i need to plant per plant.
Cosmo Seed Spacing
Hi John,
Plant Cosmo seeds 2 feet apart to give them adequate space. This distance also gives them the benefit of leaning on each other when they are mature.
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