Asters: Stars of the Fall Garden
August 21, 2017
Summer is winding down but the asters are just getting started, adding splashes of lavender, purple, and pink to the fall garden.
A native American plant, the aster got its name from the ancient Greek and Latin words for star, describing its radiant blossom. One of its common names is starwort. As early as 1680, Europeans were importing our native wild asters for use in their Old World gardens. In England today they are called Michaelmas daisies for their habit of blooming around the same time as the Feast of St. Michael on September 29th. They are also the birth flower for September.
The Perfect Fall Perennial
Like many native plants, asters are often overlooked when people plan their flower beds but the reliability of their stunning blossoms during a time of year when other perennials are winding down is something we should be taking advantage of. They not only rescue the fall garden from boredom but also provide nectar for butterflies tanking up before heading south for the winter. They thrive with minimal care and there is a galaxy of starry asters to choose from:
New York aster (Aster novi-belgii) grows 2-3 feet tall with violet-blue flowers and narrow leaves. There are cultivars in dark blue, lavender, and pink too. The dwarf form grows only 10-15 inches high and spreads readily.
New England asters (A. nova-angliae) are late bloomers, grow 3-6 feet tall and are well branched with lots of small purple flowers.
‘September Ruby’ is a deep cerise red variety that grows easily from seed. At maturity it will be about 5 feet tall. Hot pink ‘Alma Potschke’ grows 4 feet tall and is perfect for a back of the border accent. ‘Purple Dome’ is the first true dwarf NE aster growing only 18 inches tall. It will be covered with deep purple blossoms for at least a month.
If powdery mildew plagues your garden in fall, Aster dumosus is a low-growing ground cover that is 8-12 inches tall. Try ‘Woods Purple’, ‘Woods Pink’, or ‘Woods Blue’. They all appreciate full sun and are mildew free.
Not to be overlooked is Aster frikatii ‘Monch’ which is long blooming, grows 2-3 feet tall and bears large 2 1/2 inch lavender-blue flowers.
Though most asters require full sun and lots of water there are some varieties that are drought tolerant and thrive in partial shade:
The smooth aster (A. laevis) is mildew resistant and performs well in dry shade. It grows 3-5 feet tall and has fleshy dark green leaves on dark purple stems. The variety ‘Bluebird’ bears clusters of sky-blue flowers atop a vase-shaped plant.
The white wood aster (A. divaricatus) bears a cloud of white blossoms atop dark brown, wiry stems. A woodland plant, it spreads by seeds and underground runners. It will thrive in the dry soil and dappled shade found under tall oaks and maples but can be invasive.
The blue wood aster (A. cordifolius) has heart-shaped leaves and grows up to 6 feet tall in the right location. It tolerates shade well but prefers rich, humusy soil. It will reward you with a dense cloud of small blue flowers from late summer through mid-fall.
Aster Growing Tips
To promote bushier growth, cut your asters back in early spring and again in June. During a dry summer they tend to drop their lower leaves if not kept well watered. To cover their “naked legs”, plant lower understory plants around them. As the plants mature they grow out from the center eventually leaving a dead spot in the middle. The benefit greatly from dividing and replanting in the spring every 3 to 4 years. Feed plants in the spring with a top dressing of compost or well-rotted manure. Tall growing varieties will need staking.
Make some room in your garden for one or more of these stellar performers!
About This Blog
Get inspired by Robin Sweetser’s backyard gardening tips and tricks. Robin has been a contributor to The Old Farmer’s Almanac and the All-Seasons Garden Guide for many years. She and her partner Tom have a small greenhouse business and also sell plants, cut flowers, and vegetables at their local Farmer’s Market.