4 tips for growing cosmos in your garden

June 23, 2015

With their long, slender stems and lacy foliage, cosmos are an attractive, fast-growing way to add colour to the garden and they make great cut flowers, too.

4 tips for growing cosmos in your garden

What kind of cosmos to grow?

Most cosmos are grown as annuals.

  • The most popular of several species is Cosmos bipinnatus, a native of Mexico, which sports red, white, pink or purple flowers up to 10 centimetres in diameter on top of 1.2- to 1.5-metre stems.
  • Another species, C. sulphureus, boasts eight-centimetre flowers in shades of yellow and orange, and it's a great choice if you live where summers are hot and humid.

1. Find the ideal soil

  • Lean, well-drained, sandy soil is actually the preference for cosmos.

Don't give them large doses of fertilizer, or the plants will become giants that won't bloom until late summer.

  • Instead of fertilizer, make sure your cosmos get plenty of bright sunlight and adequate moisture.

2. Grow from seed

Cosmos are easy to grow from seed.

  • Sow seeds right in the garden from spring to early summer.
  • If you buy seedlings or start seeds indoors, set out the little plants at about the time of your last spring frost.

3. Get deep in the soil

  • Plant seedlings deep, so that all but the top ten centimetres  of stem is buried.

Like tomatoes, cosmos often develop roots at the base of their stems.

  • As the plants grow, hill up a little soil around the base of each plant, which encourages them to bush out and stand steady in gusty summer storms.

4. They can smell delicious

  • For a distinctive aroma of cocoa, try chocolate cosmos (C. atrosanguineus), which has dark burgundy blooms and velvety petals.

Many flowers smell great, and it's an incredible to think that you can pick which great smell you like best.

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