Sulphur Cosmos Seeds - Red Cosmos sulphureus

How to Plant & Grow Cosmos Flowers from Seeds

This Mexico native is one of the simplest flowers to grow, and they are suitable for all zones. Since they reseed themselves easily, they make perfect additions to wildflower meadows or naturalized areas. Children will love planting their cosmos seeds and watching them grow taller than they are!

Sow your Cosmos seeds in the full sun to partial shade. As cosmos flowers are very adaptable, they can thrive in average to poor soil quality, and they are tolerant to dry conditions. Scatter cosmos seeds outdoors after there is no longer a danger for frost. Seeds can be covered ¼ inch since they do not need light to germinate. Germination will usually occur in just 3 to 5 days, but it can take up to 2 weeks.

Once started, cosmoses require virtually no attention. You can add a general purpose fertilizer once or twice a season. If a plant grows very tall and is not planted in a wind protected area, it may require staking. If you want blooms all summer long, dead head the old blooms.