The word cosmos derives from the Greek word for an ordered universe. The flower cosmos earns its name for having evenly spaced petals that are in harmony, much like the universe. This plant, which is native to Mexico, was named by Spanish missionaries who grew them in their gardens. The plant is known for growing well under hot, dry desert conditions where many other types of flowers wilt. Plant cosmos seeds in midspring for showy displays throughout summer and early autumn.
Select soil that is rocky or sandy and in full sun. Cosmos planted in fertile soil tends to be lanky and tall.
Break up the soil as soon as all danger of frost has passed and the soil has warmed to 18.3 degrees Celsius (65 degrees Fahrenheit). Cosmos are not frost tolerant and will not germinate until the soil is warm enough.
Scatter seeds over the seed bed. Cosmos plants do not need to be evenly spaced.
Rake the seed bed to cover seeds with soil. Cosmos will not sprout if buried too deeply.
Water soil with a garden hose and hose end sprinkler until the soil is as damp as a wrung-out sponge. Keep the soil damp for seven to 10 days. The seeds should germinate from between seven and 21 days.