The Ultimate Guide to Cosmos

Cosmos is an absolute must-have in your garden. A gorgeous cottage garden favourite. Cosmos are half-hardy annuals- that means they grow, bloom and set seed and die all in one year, meaning that you need to sow fresh seed each year. 

The good news is that these are quick and easy to grow from seed, flowering in as little as 12 weeks. These are brilliant in borders and also can be planted in containers or pots too.

Sow Cosmos seed into module trays or pots, leave on a warm sunny windowsill until germinated and then move into a zippy or greenhouse and grow under cover, watering occasionally to ensure the soil doesn't dry out.


Once your Cosmos seedlings have two set of leaves, you can 'pinch them'. Watch this video for guidance on how to 'pinch' them for bushier plants with more flowers.

In May, harden them off for around week by placing in either an open cold frame or on a patio, before planting the Cosmos plants out where they are to flower. 

They look best when planted in 'three's' so the borders look full.
Ensure you deadhead Cosmos throughout the season. By taking off the spent flowers this will encourage more flowers to bloom. You can also feed the Cosmos plants with tomato feed weekly or fortnightly for even more flowers.


If you haven't already purchased your Cosmos seeds then go and have a look at my 'Cute Cosmos' pack or the individual seed packets which are available. 

Plus, do share any pictures of your Cosmos with me @therosepressgarden- I absolutely love seeing your photos!


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