Growing Cosmos from Seed
Cosmos are wonderful for cutting as they are such abundant and giving flowers and have a very good vase life. They are also really good for pollinators, and well worth adding into your borders or growing them as cut flowers.
Thankfully, they are also really easy to grow!
Growing cosmos from seed:
Prepare your growing medium by either sieving peat-free multipurpose compost or using specialised seed compost. We also tend to add a handful of vermiculite to help aerate the soil.
Add compost to your growing container. You can either grow them in a seed tray and prick them out once they have grown their ‘true' leaves, or grow them in a tray with module cells (these will still need potting on, but can be preferable as their roots tend to be disturbed a lot less).
Place your seeds and cover them so they are about 3mm deep.
Label and water.
Place in a greenhouse or on a warm windowsill to germinate.
Sow about 4 weeks before the last frost is expected in your area, then you can plant the seedlings out into the garden after all the dangers of frost damage have passed.
If you’re growing for cut flowers, note that cosmos can get quite bushy, so do need room to grow. It’s recommended to leave about 30-40cm apart and stake or net them early. It’s also worth pinching them out which will encourage good vigorous growth. Also, make sure you deadhead regularly to prolong their flowering period and they will reward you with many, many beautiful blooms!
Author - Hannah Clarke
