Take a cue from Mother Nature with this loosely planted display of cosmos.
Cosmos come in various colors, from burgundy to pink to white.
Mix them up for a more natural look, like a wildflower meadow.
Credit: Laurey W. Glenn
Bonus: this colorful flower, native to tropical America, attracts birds andbutterflieswith its cheery blooms.
Because of their wildflower characteristics, cosmo flowers are considered invasive in some environments.
Light
A true summer flower, the cosmos thrive in full sunlightat least eight hours daily.
Some cosmos varieties will grow in partial sunlight but tend to bloom less than those that receive proper sunlight.
The native regions for cosmo flowers have hot summer conditions, so replicating this environment is best.
Cosmos will perform poorly in rich soils because the extra nutrients cause the plants to overdevelop and droop.
If this occurs, adding stakes can help save some of the cosmos.
Water
Cosmos are relatively drought-tolerant, so these plants only need limited watering after establishment.
Overwatering can lead to overfertilization and less showy bloomsonly water when the soil is dry and ensure proper irrigation.
Don’t plant seeds until after the last frost to help promote healthy blooms.
Fertilizer
As a maintenance-free plant, the cosmos do not require fertilization.
Too much fertilizer can cause less showy blooms and the foliage to overdevelop.
Types of Cosmos
Pruning
Encourage new blooms by deadheading spent flowers.
Leaving the cosmos with a few flowers on the plant can help encourage self-seeding.
Propagating Cosmos
Cosmos can self-seed and take about seven to 21 days to germinate.
While germinating takes place, keep the soil moist.
Beyond deadheading spent flowers and trimming back the branches, the cosmos will die in the fall.
A protective covering can help prevent pests from eating the cosmos.
Other diseases that impact the cosmos from developing are stem canker, powdery mildew, and Botrytis blight.
Remove diseased stem sections or use insecticidal soap if these diseases are present.
Proper maintenance includes plenty of sunshine and moist, well-draining soil.
Deadheading spent flowers will also encourage new growth.
The lower you cut back the stems, the longer it will take for new blooms to emerge.
Common Problems With Cosmos
Cosmos thrive in full sun, well-drained soil, and with proper maintenance.
Planting cosmos in an area with direct sunlight and proper circulation will help prevent powdery mildew from forming.
Also, maintaining adequate water without oversaturating the plants will help.
If powdery mildew is present, try spraying a fungicide on the leaves according to the direction.
Soil with a high nitrogen concentration can also negatively impact the flowers' potential for full blooms.
