Cosmos Flower Temperature. May 18 2021 Cosmos are tolerant of most soil pH levels but grow best in neutral to alkaline soils. Avoid overwatering or overfeeding chocolate cosmos.
The seeds may be sown outdoors after all danger of frost is past and the soil has warmed to at least 65 degrees F. Plant cosmos in a place where they will receive full sunlight or about 6 to 8 hours of direct sun per day and in a location where they are protected from harsh winds. Just sow seeds lightlyno more than -inch deep.
Most gardeners grow cosmos as annuals although they can be perennials in USDA hardiness zones 9-10.
Rich fertile conditions are not necessary to grow yellow cosmos but adequate drainage is. Maintaining a soil temperature of 65 degrees Fahrenheit encourages quick and even germination. The daisy-like flowers of chocolate cosmos measure 1 across and are very attracive to butterflies. This plant will thrive best in slightly acidic or neutral soil.