Growing cosmos flowers is easy!

The versatile cosmos is a generous and easy addition to your cut-flower patch, writes Eliza Henry-Jones.

A mix of 'Picote' and 'Purity' cosmos flowers.
Photo: Melanie Kercheval

Native to Mexico, cosmos are part of the sunflower (Asteraceae) family. They are the sort of plants that give far more than they demand, providing ample food for bees, butterflies and other beneficial insects foraging in your garden. 

Soil and position

Cosmos is an unfussy plant – I tend not to worry too much about the soil in our cosmos beds because they’re really quite happy with whatever they’re given. Cosmos loves heat and doesn’t enjoy having wet, boggy feet. Planting somewhere sunny with good drainage will help keep your cosmos blooming throughout summer. On the hottest of days when so many plants seem parched and listless, cosmos will still be thriving.

Pinching and staking

To promote more vigorous growth, ‘pinch’ your cosmos plants when about 20cm tall. This means taking the top few centimetres off your plant. Make sure you make the cut with clean, sharp snips, just above an existing set of leaves. 

After pinching, your plant will send up new stems, which will ultimately result in stockier more robust bushes and more gorgeous blooms. 

Cosmos plants will generally top 1 metre when fully grown. Many growers advise staking or netting. However, they seem to do just fine without support in my relatively unsheltered patch, giving me plenty of flowers to share!

Eliza Henry-Jones has written all about planting cosmos in the Spring 2021 issue (OG 128). You can get a copy delivered to your door by ordering onlineOr look for the tomato cover at your newsagents!

128 cover

By: Eliza Henry-Jones

First published: October 2021

Related topics

Gardening Basics, Spring, cosmos, annual flower, cut flowers, Issue 128 -- September/October 2021, Ornamentals