How to Grow Cosmos Plants in your Garden

Gardener's HQ Guide to Growing Mexican Aster, Ulam Raja, and Cosmea

Members of the Cosmos plant genus are half hardy perennials or half hardy annuals.

They bloom with daisy like flowers in rich red, yellow, orange, pink or white.

They generally have stalks of about 30 to 120 cm in height (depending on species).

Common names for Cosmos include Cosmea and Mexican Aster.

How to Grow Cosmos

If planning to grow Cosmea, Mexican Aster and other Cosmos members outdoors then the seeds should be sown out after the last frost of spring at a depth of 3 mm (1/10th inch / lightly cover).

They prefer to grow in a sunny area of the garden that has poor soil of PH 5 to 7.

If you are planning to fist grow Cosmos indoors as starter seedlings, then they should be started off about five weeks before they are due to be put out in spring (following the last frost).

They take about half to one and a half weeks to germinate at a temperature of about 21 to 24 degrees centigrade.

Caring for Cosmos in the Garden

Once growing it is best to pinch out the growing tips of the plant when it reaches an height of about 40 cm to encourage bushiness and more blooms. Cosmos requires watering during prolonged dry spells.

I hope that you enjoyed this guide on how to grow Cosmos plants. You may also enjoy the following Gardener's HQ growing guides: How to grow Liatris spicata and Senecio plants.