Cosmos (Rubenza)

Growing Instructions

Cosmos flourish in warm weather and are best planted in late spring after all danger of frost has passed. They grow quickly and generously. You can direct-sow seeds into the garden in full sun, and the seeds will germinate in about 7–10 days in warm soil. Alternatively, you can start them indoors 4-6 weeks before the last frost date to get a head start. If you transplant, though, handle the seedlings carefully when since they don't like if their roots are disturbed too much. Space the plants about 9"-12" apart. Cosmos are not picky about soil and actually bloom better in average or even poor soil. Too much fertilizer (especially nitrogen) can make them grow super leafy with fewer flowers. Once established, cosmos are very drought-tolerant and generally only need watering if you have a prolonged dry spell. No deadheading is strictly required (they’ll keep blooming regardless), but removing spent flowers can make the plants look tidier.