Cosmos: A Guide to Blooming Beauties
Cosmos are showy annual plants that add a splash of color to any garden. They are part of the Compositae family, which also includes sunflowers, daisies, and zinnias. The two most common species of cosmos grown in home gardens are Cosmos sulphureus and Cosmos bipinnatus.
Types of Cosmos
- Cosmos sulphureus: This species has long, narrow leaves and produces flowers in shades of yellow, orange, or red.
- Cosmos bipinnatus: This species has finely cut leaves that resemble fern fronds and produces flowers in shades of white, rose, or pink.
Why Are My Cosmos Not Blooming?
If your cosmos plants are not blooming, there could be several reasons:
Immaturity
Cosmos plants take about seven weeks to mature and produce blooms from seed. If your plants are young, they may simply need more time. Check the tips of the stems to see if they are starting to produce buds.
Over Fertilization
Too much nitrogen fertilizer can prevent cosmos plants from blooming. Nitrogen is an essential nutrient for healthy green growth, but too much can be a bad thing. If your cosmos plants have produced a lot of healthy-looking leaves but no flowers, you may be overfertilizing them.
Other Concerns
- Old seeds: Cosmos seeds lose their viability after about a year. If you are using old seeds, they may not germinate or produce blooming plants.
- Cold weather: Cosmos prefer warm, dry weather and may not bloom if they are exposed to extended periods of cold or wet weather.
How to Encourage Blooming
If your cosmos plants are not blooming, there are a few things you can do to encourage them:
- Provide adequate sunlight: Cosmos need full sun to bloom properly. Make sure your plants are getting at least six hours of direct sunlight per day.
- Avoid overfertilizing: Cosmos do not need a lot of fertilizer. Fertilize them lightly at the time of planting, and then only once a month during the growing season with a non-chemical fertilizer like fish emulsion.
- Use bone meal: Bone meal is a natural fertilizer that can help promote blooming in cosmos plants. Sprinkle it around the base of your plants and work it into the soil.
- Deadhead spent blooms: Deadheading, or removing spent blooms, encourages cosmos plants to produce more flowers.
Troubleshooting Cosmos Blooms
If you are still having trouble getting your cosmos plants to bloom, here are a few additional troubleshooting tips:
- Check for pests and diseases: Pests and diseases can damage cosmos plants and prevent them from blooming. Inspect your plants regularly and treat any problems promptly.
- Provide support: Cosmos plants can grow tall and leggy, so they may need support to keep them upright. Stake your plants or grow them in a cage to prevent them from falling over.
- Overwintering cosmos: Cosmos are not frost-tolerant, so they will need to be overwintered indoors in cold climates. Dig up your cosmos plants in the fall and store them in a cool, dark place until spring.
With a little care and attention, you can enjoy beautiful cosmos blooms in your garden all season long.
