Fall Color - Asters
We can thank the Victorians for making chrysanthemums the classic flower of autumn. Prior to that, the aster, or Michaelmas Daisy, was the symbol of the fall season. Instead of the rusty reds, oranges and yellows that make us think of fall, the purples, pinks and whites of asters were considered fall colors. The nickname “Michaelmas Daisy” refers to the Feast of St. Michael the Archangel which is celebrated on September 29 when the asters are blooming.
Asters are perennials that are native to the Northern Hemisphere. They are hardy from growing zone 3 through zone 8. They will grow in full sun as well as partial shade. They prefer well-drained soil that is slightly acidic with a pH of 5.8 to 6.5. Be careful not to over-water them. Like many native plants, asters are drought tolerant and prefer less water. They are also susceptible to powdery mildew so it is best to water them at the roots rather than from overhead.
Asters have been heavily hybridized so they range in size from groundcover plants of only 4 inches tall to the 3 feet height that is the norm for native asters. The taller varieties should be staked to prevent them from falling over in the wind.
Like mums, asters are photoperiodic. Starting at the end of August as the days grow shorter and the nights grow longer, asters begin to set buds which will bloom in September. To maximize the number of flowers, pinch your plants early in the growing season to make them bushier and produce more blooms.
After the first hard frost, when the foliage has died, cut the entire plant down to the ground and remove it from the garden. Don’t worry, the roots are still alive underground. Your asters will be back in the spring.
The name “aster” is from an ancient Greek word meaning star which refers to the shape of the flower.
Asters can be grown from seed, but germination is spotty. The seeds need to be cold stratified before you plant them. Keep them in your refrigerator for 4 to 6 weeks and then direct sow them outside after all danger of frost.
Most gardeners purchase asters as plants in the fall. They should be planted as soon as possible to give them a chance to settle into their new home and develop their root system which will help them survive the winter.
Whichever way you start your plants, you should provide them with generous spacing in your garden, usually 1’ to 3’ apart depending on their size. Proper spacing allows for air circulation which will prevent powdery mildew from developing on your plants.
Asters make excellent cut flowers. Beware! Bees love them so harvest your flowers later in the day after the bees have gone home.
Butterflies also love asters so be sure to plant a few in your butterfly garden. Since they bloom at the end of the summer as the monarchs are heading south for their winter homes in Mexico, asters provide a critical food source for them.
© 2014 Caren White