Is cosmos easy to grow from seeds? If the plant is self-seeding, this question might be rhetorical! So, how to grow cosmos seeds? Does it require special care? Let’s dive into everything you need to know about growing cosmos in your garden!
What Plant is Cosmos?
The cosmos, with a Greek name but Mexican origin, is an annual herbaceous plant that makes a fantastic ground cover. It typically grows between 35 to 120 cm tall and blooms almost all summer long until the first frost of autumn. This plant thrives in clumps or along borders, and sowing in ornamental gardens in April is ideal for a vibrant color display. Cosmos is highly sun-tolerant and not picky about soil type. In fact, it doesn’t need to be fertilized to thrive. Cutting back the plant encourages the growth of new flowers, so feel free to harvest them for your bouquets without worry.
Whether planted in pots or in the ground, cosmos requires different timing for each. Growing cosmos from seed can even be a fun activity with kids!
In What Soil Should Cosmos Be Planted?
Avoid making the mistake of sowing cosmos in your vegetable garden. The plant prefers deep, well-drained soil but not rich soil. Be cautious because the blackish fruits that appear when flowers fade are attractive to birds, such as goldfinches, who may also be tempted by your tomatoes and strawberries.
For best results, cosmos thrives in soil with good drainage and light humidity. While it is essential to water after sowing, avoid excessive watering during the flowering period.
When and How to Grow Cosmos Seeds?
The timing for planting cosmos seeds depends on your location. If you’re sowing indoors in pots or containers, start in early April and transplant the seedlings outside at the end of May. For direct planting in the open ground, wait until the end of April for flowers that will bloom by July.
How to Grow Cosmos Seeds?
Since every seedling needs warmth and light, be sure to place the cosmos seeds on top of potting soil, covering them with a thin layer (about 3 mm). Gently pack the soil, and they will germinate at a temperature of 15-25°C with moderate humidity, which can be maintained using a vaporizer.
During the growing season, if your cosmos is grown in pots, you may need to provide additional fertilizer to support healthy growth.
What About Planting Outdoors in a Month?
Cosmos plants are self-seeding, meaning they will naturally drop their seeds at the end of the season. These seeds can germinate and grow independently the following year. However, if you don’t want cosmos to become invasive, cut back the plants before they can drop their seeds or grow them in containers.
To grow cosmos outdoors, choose a sunny spot that receives at least 6 hours of sunlight a day. Cosmos will naturally help control weeds by growing tall enough to overpower them. Prepare the soil by loosening it, enriching it with compost or manure, and sow the seeds 6mm deep, with 45cm spacing.
If you’re planting directly in the ground, no need to soak the seeds before planting.
Do Cosmos Re-seed Themselves?
Yes, cosmos can re-seed itself. Once the soil warms up to 21-26°C, the seeds will take about 2 to 3 weeks to germinate. Just be mindful of potential pests and pets that may interfere with your seedlings. If you’re short on time, simply scatter the seeds and rake the area to cover them.
Growing cosmos is a fun and easy way to brighten up your garden, whether you choose to grow them from seeds or allow them to self-seed year after year! Happy gardening!
