This unfussy annual makes a colorful addition to cut flower bouquets.
Cosmos is a day-sensitive plant that blooms best in late summer when the days get shorter.
If you decide to plant cosmos, you are spoiled for choice.
Credit: Peter Krumhardt
There are more than 25 species of cosmos and numerous varieties and cultivars.
The choices dont end here.
Cosmos come with single, semi-double, or double flowers, and in sizes ranging from dwarf to tall.
Credit: Peter Krumhardt
Match the planting location with the cosmos variety.
Or, plant petite varieties in containers for a pretty splash of color on the patio.
Cosmos flowers are the most striking when planted in groups or drifts.
Credit: Justin Hancock
Anchor the cutting garden with multiple varieties of cosmos.
Because cosmos flowers are so easy to grow, they make a fun choice for a childrens garden.
The seeds should not be covered with more than 1/8 inch of soil otherwise they wont germinate.
Credit: Graham Jimerson
Keep the soil evenly moist.
The seeds will germinate in 7 to 14 days.
Light
A location that receives at least 8 hours offull sunis a must.
Credit: Chipper R. Hatter
Too much shade will lead to poor bloom and spindly growth.
Soil and Water
Cosmos grows in a wide range of soil types.
Soil with average to poor fertility and apH between 7.0 and 7.5is best.
Excellent soil drainage is a key requirement.
Keep the soil moist at all times during the seed germination period and water as often as needed.
After the seedlings emerge, water them deeply about once a week.
Credit: Jay Wilde
Once the plants are established, no watering is requiredcosmos thrives in dry soil.
Growth is stunted in temperatures below 53 degrees.
High humidity is not an issue.
Credit: Peter Krumhardt
Fertilizer
Do not fertilize cosmos.
This is a plant that thrives in poor soil.
Rich soil produces floppy, weak plants, as well as a sparse bloom.
Credit: Tom McWilliam
Pruning
Deadheading the spent flowerspromotes re-blooming and also cuts down on the self-seeding.
Potting and Repotting Cosmos
Cosmos makes a great container plant.
Choose shorter, compact varieties as the tall varieties are more prone to topple over.
Plant cosmos in a pot filled with well-draining potting mix.
double-check the container has large drainage holes.
Repotting wont be required as cosmos are annuals.
Pests and Problems
Cosmos is rarely affected by serious pests or diseases.
The plant may attract aphids.
Potential diseases include powdery mildew, gray mold, and stem canker.
Proper spacing to ensure good airflow helps to prevent diseases.
It grows 12 inches tall.
‘Cosmic Orange’ Cosmos
This cultivar ofCosmos sulphureusbears many double orange flowers that are great for cutting.
It grows 12 inches tall.
‘Candystripe’ Cosmos
Cosmos bipinnatus’Candystripe' has pure white petals edged in deep pink.
It reaches 3 to 5 feet tall.
Chocolate Cosmos
Cosmos atrosanguineusChoca Mocha is a short, compact cultivar with chocolate-colored flowers and fern-like foliage.
The sturdy stems grow up to 12 inches tall.
Cosmos Companion Plants
Celosia
There are few annual flowers as showy ascelosia.
The flowers are beautiful as fresh flowers, but you’re able to also dry them easily.
And they bloom in all the colors of a glowing sunset.
Plant established seedlings in spring after all danger of frost has passed.
Celosia likes rich, well-drained soil with moderate water.
In hot, dry weather spider mites may become a problem.
Dusty Miller
Dusty milleris a favorite annual because it looks good with everything.
Salvia (Sage)
There are few gardens that don’t have at least onesalviagrowing in them.
Most salvias don’t like cool weather, so plant them outdoors after all danger of frost has passed.
Frequently Asked Questions
It depends on the size of the plant.
Taller varieties may need staking, especially if they are exposed to high winds and heavy rain.
Shorter, bushier plants usually dont need staking.
As the temperatures drop in the fall, cosmos reaches the end of its annual lifecycle and dies.
