Cosmos – Easy Care Annual That Does Not Mind Poor Soil

Do you possess a brown thumb instead of a green one?   If your soil very poor?  Then this is the flower for you!  One of the easiest annuals to grow from seed is Cosmos. They are prized for their prolific, silky, daisy like flowers and their  easy-care nature in the garden. They will tolerate even poor soil conditions and make lovely cut flowers.   They even seem to thrive on a bit of neglect.

Candy Stripe Cosmos

Photo adaptation from one found onAmerican Meadows

Can I Grow Cosmos in My Garden?

Absolutely!  Cosmos are one of the easiest plants to grow and actually like a bit of neglect.

Growing tips for Cosmos:

  • Plant Cosmos in full sun (they don’t mind afternoon shade in the hottest conditions) and give them protection from strong winds.  I plant mine along a fence line with sunflowers and they are a delight to behold.
  • Cosmos need even moisture to get started, but when they mature, they are very  drought tolerant which makes them great for our North Carolina summers.  As with all annuals, they will produce more and larger flowers, if they are watered regularly.
  • The plants get quite high. Mine were about 4 feet tall last summer.  They are not too bad about flopping over, so not much in the way of  supports is required.
  • Cosmos will flower from early summer until frost.  Plant them after the date of your average last frost.  Don’t worry if you accidentally plant them too early  They are a self seeding and seem to “know” when to germinate, so the seeds won’t suffer from exposure to a late frost.
  • Don’t fertilize.  If you do, you will end up with lush foliage and not many flowers.  Cut the plants in half when the seed pods outnumber flowers.  This will rejuvenate the plants for the second half of the growing season.

There are so many types of Cosmos available that it is a matter of personal choice. (I wrote about the Chocolate Cosmos in a previous article.) One of my Favorites is the Candy Stripe Cosmos. It is available at  American Meadows. Just click the picture below for more information.

Have you grown Cosmos from seed?  What is your favorite variety?  Please leave your comments below.

Disclosure of Material Connection: Some of the links in the post above are "affiliate links." This means if you click on the link and purchase the item, I will receive a small commission from the sale, but the price is the same for you. I am disclosing this in accordance with the Federal Trade Commission's 16 CFR, Part 255: "Guides Concerning the Use of Endorsements and Testimonials in Advertising."

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  8 comments for “Cosmos – Easy Care Annual That Does Not Mind Poor Soil

  1. AJ
    04/13/2015 at 2:23 pm

    How long do Cosmos take to germinate ? I planted some Cosmos Summer Sunshine last Wed (APril 8) , hvnt’ seen any seedlings so far. Also , are they good to be transplanted?


    • admin
      04/13/2015 at 3:05 pm

      Hi Aj. I can’t remember exactly, but when I planted mine, I am pretty sure they were up in about a week. Does it say how long to germination on your seed package? They do need moisture until they get going but are pretty heat resistant and drought resistant after that.


  2. AJ
    04/13/2015 at 3:14 pm

    Well, I got these seeds from the library seed share program, didnt find much info on the package. Also, I have them in starter pots, without a plastic lid or cover on top. Should I cover them , to help them retain moisture ? Its getting warmer here (Bay area, california)


    • admin
      04/13/2015 at 7:33 pm

      Hi AJ. Covering does help to retain moisture but be sure to remove at first sign of life.

      Some seeds just don’t germinate. I would have thought they would by now.

  3. Gladie Peuler
    06/07/2017 at 10:12 am

    HI..when you plant outside from picked seeds from last year. Can you just sow them on top of the soil or do they have to be covered with dirt.

    I did it last year and they were awesome, I just don’t remember this step!’

    Thanks so much

    • Carol
      06/07/2017 at 10:14 am

      Hi Gladie. I always cover mine lightly. Carol

  4. Michelle
    06/28/2018 at 5:00 pm

    I started dahlias, Cosmos, and Shasta daisy seeds inside. I live in zone 6, Boston area. Rooted cuttings of the dahlias, have plenty of shasta’s but only one cosmos still alive. On the last transfer to larger pots, I lost all but one.
    What did I do wrong? They were growing great outside. I read your article and only got one flower that I wouldn’t even call a flower. It was more of a bud that tried to flower but didn’t make it all the way. I didn’t know that Cosmos don’t like fertilizers. That is most likely the reason for only one bud. After two days of being placed and divided into larger pots, slowly all but one withered and eventually died. I lifted to check the roots, they were not great and noticed that the stems got soft. I transferred them prior and didn’t loose any, maybe one-two.
    What should I do with one cosmo? Plant it anyway??

    • Carol
      06/28/2018 at 9:34 pm

      Hi Michelle. Soft stems sounds like rotting. That would normally happen with too much water. I’d still plant the one, but there is probably also time to try growing it again from seed. Seedling grow quickly this time of the year. You might just need to start over. Carol

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