The Difference Between Daisies and Cosmos
Daisies and cosmos are kissing cousins. Don’t search for identical genus names — cosmos fall into the Cosmos genus, while daisies are split between multiple genera like Chrysanthemum, Dendranthemum and Leucanthemum. All, however, are members of the Aster family (Asteraceae or Compositae). And the similarities do not end there, even though there are differences between the species too.
Flowers
Both cosmos and daisy blossoms are bright and simple. A kid drawing her very first blossom might well sketch the circular central eye surrounded by numerous petals. Although modern daisy cultivars are available in many colours, original plants such as Bellis perennis produce white petals around inner disks of yellow. The wide-eyed blossom resembles the sun or “day’s eye,” for which it was reputedly nicknamed. Native cosmos blush in pink tones, but cultivars are available in a vast assortment of colors from white to vibrant pinks and purples to chocolate brown. Typical daisy petals are long and slim, perfect for he-loves-me-loves-me-notting, while cosmos’ petals tend to be wider and uptipping so that the blooms could accurately be described as cup-shaped.
Foliage
Both daisies and cosmos stand tall in your own garden. How tall the depths develop depends upon the species, but a few cosmos rise to the height of a short person, while daisies usually stop growing at approximately 18 inches. Both species have stiff stems that make them ideal cut flowers, but the leaves vary. Cosmos leaves appear like green threads attached to the stalk all the way up to the blossom. Most daisy species have more conventional oval or rounded leaves clumped at the bottom of the stem.
Annuals or Perennials
A casual scan of the Net will tell you that the daisy is a perennial and the cosmos an annual; as far as it goes, the statement is correct. Several daisies grow in evergreen clumps that last for multiple years in your lawn, while most cosmos do not. On the other hand, the issue is more complex, because a few daisy species are strictly annual, and a few perennial daisies are grown as annuals in cooler climates. Similarly, a few cosmos are perennials, such as the chocolate cosmos (Cosmos atrosanguineus).
Care
Whether you have a green thumb or not, daisies and cosmos will thrive in your lawn. Both are nearly foolishly simple to grow in U.S. Department if Agriculture plant hardiness zones 8 through 9, and lots of cultivars stretch that range in the two directions. You can sprinkle your seeds in ordinary garden soil and neglect fertilizer; provided that the flowers get sun and occasional water, their pretty heads will likely appear and thrive. They are harder to get rid of than to plant, because both daisies and cosmos reseed themselves generously.