The cosmos is such a delight to grow in the garden. Just give it full sun and the annual will produce endless blooms during the summer season. The plant also attracts butterflies, bees, and birds to your space for a nice, natural setting.
When growing cosmos from seed you may ask, ‘how far apart to plant cosmos?’ Let’s take a look at the proper spacing for various cosmos varieties.
How Far Apart Should You Plant Cosmos Seeds?
Cosmos flowers look great when bunched together, but to promote better plant health and longevity then you should observe proper spacing in-between them.
When planting cosmos in an open yard or garden you should measure a space of 12-18 inches for each seedling on bigger varieties and around 8-10 inches for smaller varieties.
This gives each cosmos seedling generous room to grow and branch out. You shouldn’t worry about seeing blank spaces as cosmos can fill them in pretty quickly and when the plant begins branching out.
If you’re growing cosmos from seed, then you can spread two or three in two-inch spaces. Thin the weak ones out after a week and leave a 12-inch space for the healthy specimens. Alternatively, you can start the seeds indoors and wait until the temperature gets warm outside to plant them in your garden.
How Do You Plant Cosmos?
Cosmos seeds can be sown directly on the ground or on a seed tray at around half an inch deep. Water the seeds and keep them evenly moist until cotyledons sprout (in about 5-7 days). Warm weather or environment will help with faster germination and give you a headstart on growing cosmos.
Cosmos thrives in heat and full sun, and it’s important that you provide both. Choose a spot in your yard or garden that gets direct sunlight all day and plant them at a spread of 12 to 18 inches. What’s remarkable about the cosmos is that they still do well even if the soil is poor and will grow colorful flowers with very little encouragement from you.
It takes around 7 to 9 weeks for the cosmos to grow flowers from seed. If you plant them in spring then you should have an abundance of blooms come early to mid-summer. Cosmos starts small but soon grows to around six feet in height (or 72 inches) in an open space. In containers, these plants grow to around three to five feet in general.
Should I Pinch Out Cosmos?
To encourage a cosmos plant to branch out more you can pinch out the growing tip when it’s around 6 to 8 inches tall.
Cosmos can be pinched when there are three sets of true leaves, or when they get taller. You can use a pair of sharp scissors or your fingers to remove the growing tip of the plant. Snip off the top two or three inches while leaving at least two sets of true leaves to force the plant to produce side shoots. This also makes the stems thicker so they can support more branches and subsequent flowers.
As an annual, cosmos tend to grow, flower and seed in a single growing season. To prevent your cosmos plants from getting too leggy you should place them where they can get full sunlight throughout the day. Feeding with fertilizer is not needed as they favor poor soil.