How to sow cosmos, step by step. In this article, we will learn step by step how to germinate cosmos seeds and get flowers until autumn.
Blooming continuously from mid-summer through fall, this is one of the best annuals.
The flowers are excellent for arrangements and come in shades of white, pink, lilac or purple, with yellow centers.
Cutting the flowers regularly will generate a constant bloom until the first frosts.
Cosmos grow big and fast and form almost bushes. They should be pruned very early to encourage compact growth.
The light green feathery foliage is also very attractive. This plant is also very useful for filling empty spaces in the beds as it grows quickly and the bed will soon be composted.
Do not plant cosmos in soil that is too rich, otherwise they will produce too much foliage and little or no flowering.
While many annuals can be sown directly in the garden, sowing early in a sheltered location gives the plants a head start in growth and more assured germination which generally yields better results.
Cosmos seeds are best sown in trays and kept warm in a greenhouse, greenhouse or even on a sunny windowsill.
You can buy Cosmos bipinnatus seeds at garden centres, supermarkets or online. Check the package to see if the seeds are within their expiration date and in good condition. If you need to store seeds for some time, do so in a cool, dry place. A refrigerator is perfect for this.
Cosmos seeds are small but easy to handle.
when to sow
Cosmos can be sown from late winter to mid-spring . You can start them earlier in a protected place. Bear in mind that they will need to be protected until the last frost has passed.
how to sow
Fill the tray with good quality seed compost adding a little sand for good drainage. Leave some space below the border. Lightly press down on the soil to make it firmer.
Distribute the seeds.
Don’t sow too much… This was a mistake I made, I put too many seeds, and then I’ll show the result later in this post.
Look how close they got… the cosmos germination rate is very high…
Then lightly cover the seeds with more soil. Water the tray with a fine-grained watering can or immerse the tray in a bucket of water so that it is absorbed slowly from the bottom upwards.
Then you can cover the seed tray and keep it protected to improve germination. A temperature of 20 to 23ºC is ideal for germination to occur.
how to plant
6 days after sowing, there are already small cosmos emerging.
They grow very fast.
When the seeds have developed a few leaves, it’s time to plant them individually. In the photo below, the seedlings are ready to be replanted individually and allowed to grow before being planted in the final location. A month passed between sowing and the photo below.
See how tight and very skinny they are. A third of the seeds would have been perfectly sufficient.
Lift the small plants and plant them in small pots.
Allow the cosmos to grow and develop. They are fast growing.
You should prune the top to encourage side shoots which will result in more compact plants.
By doing this you will also be creating more shoots that will produce flower buds.
Finally, when they are robust, plant them in their final location. Keep the plants watered for the first few weeks until they become established, then gradually reduce watering.
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