Perennial asters (Aster spp.) are the most common type of aster. Numerous species and about 200 cultivars are known to exist, with plant stolons reaching a height of up to 12 feet. It is possible to find aster flowers in a wide range of colors ranging from blue to pink to purple to red to white. The majority of them bloom in the fall, but there are a few species and cultivars that flower at other times of the year. Despite the cold weather, there is still an aster that blooms. Asters can bloom year-round in your garden if you pick the right ones.
They are daisy-like perennials with starry flower heads that can be white, blue, or purple. In the late summer and fall, when many of our summer blooms are beginning to fade, they add a lovely touch to the garden. In the garden, here’s how to grow asters:
When it comes to the Asters
There are a wide variety of asters to choose from! New England (Symphyotrichum novae-angliae) and New York (S. novi-belgi) asters are the most commonly seen in home gardens, but garden centers also carry a variety of hybrid asters in vibrant pinks, blues, and purples. You may also be able to find “wild type” species that are native to your area, even though they may not be as eye-catching as the cultivated varieties in some cases. Find out more about the varieties we recommend in the following section of the page.
Asters are a major source of nectar for pollinators in the late season because of their ability to draw in large numbers of bees and butterflies. They’re also sometimes referred to as “Michaelmas daisies” because of their late-blooming time, on September 29th, which is Michaelmas!
For example, it can be used as a border in a rock garden or in a wildflower garden. With a height range of eight inches to eight feet, you should be able to find a plant that will work in your yard.
Planting Site Selection and Preparation
- For asters, a cool, moist summer climate is ideal, with cool nighttime temperatures in particular. Plant asters away from the hot midday sun if you live in a warm climate.
- Select a location that gets a lot of sunlight.
- Soil should be moist but well-drained, and loamy.
- Before planting, amend the soil with compost.
Asters can be grown from seed.
- Aster seeds may germinate, but this is not always the case. Sowing seeds in pots or flats and storing them in the refrigerator for 4 to 6 weeks can simulate winter dormancy and be done indoors during the winter. Germination can only begin during this time of cooler weather.
- Seeds should be sown one inch deep in soil in a bright area of your house. During the spring, transplant young plants outside when the risk of frost has passed.
- Early to mid-spring is the best time to plant young asters. You can begin planting aster seedlings as soon as they are available in your region (typically in the fall).
- If the aster is expected to grow in size, you should place it between 1 and 3 feet apart.
- Make sure your plants get plenty of water when they are just starting out.
- Keep the soil cool and weed-free by mulching after planting.
Getting Started with Asters: A Comprehensive Guide
- Every spring, apply a 2–inch layer of mulch and a thin layer of compost (or a portion of balanced fertilizer) around the plants to encourage vigorous growth.
- Remember to water your plants frequently during the summer if you get less than an inch of rain a week. The problem is that many asters are water-sensitive; if your plants have too much moisture or too little moisture, they may lose their lower foliage or not flower well. To prevent flower drop, keep an eye out for stressed plants and experiment with different watering techniques.
- The taller varieties should be staked to prevent them from toppling.
- When you pinch back asters in the early summer, they’ll grow bushier and produce more flowers. No worries, they’ll be able to handle it!
- You can either cut the asters back in the fall or leave them in the garden for the winter to add color and interest to your garden during the dormant season.
- Aster flowers that are allowed to fully mature may reseed themselves, but the resulting asters may not bloom the same way they did the first time around. This means that you may not get the exact same color flowers you planted!
- Divide in the spring every two to three years to keep your plant’s health and flower quality in check.
Pests/Diseases
Susceptible to the following conditions:
- Powdery mildew
- Rusts
- White smut
- Leaf spots
- Stem cankers
- Aphids
- Tarsonemid mites
- Slugs and snails
- Nematodes
Types of Plants to Consider
The New England aster (Symphyotrichum novae-angliae) and the New York aster are the most common asters in North America (Symphyotrichum Novi-belgii). Native to North America, both of these plants attract a wide range of beneficial insects to their blooms. Talk to your local Cooperative Extension or garden center for advice on which species of aster are best suited to your area if you’re considering using a non-native one.
Spring
Alpine asters (Aster alpines) bloom from the middle of spring to the beginning of summer, reaching a height of 6 to 12 inches. Purple-blue petals surround yellow centers on 1-inch daisy-type flowers. These are hardy in USDA plant hardiness zones 4 to 9, but they may not thrive in areas with hot, humid summers. Plants in hot-summer climates may benefit from a location with afternoon shade. East Indies asters (Aster tongolensis) grow to a height of 1 to 2 feet and bloom from late spring to midsummer. Their flowers have violet petals and orange centers and measure 2 inches in diameter. Full sun exposure is ideal for these plants, which are hardy in USDA zones 5 to 8.
Summer
Aster x frikartii “Monch” and Aster amellus “Rudolf Goethe” are Frikart’s aster hybrids that bloom in the middle of summer. Monch” is a 2- to 3-foot-tall plant with 2-inch-diameter lavender-blue petals and yellow centers. USDA zones 5 to 10 can withstand them. Although light frost may affect them in some areas, they typically bloom until mid-fall in most climates in these zones. It has 1 1/2-inch-diameter dark lavender flowers on a 2-foot-tall plant called “Rudolf Goethe.” A hardy perennial, it blooms from the middle of summer into the fall in USDA zones 5 to 8. Both of these asters thrive in a location with direct sunlight.
Fall
Aster tataricus “Jindai” and the “Snow Flurry” heath aster hybrid (Symphyotrichum ericoides “Snow Flurry”) bloom in the early to mid- or late autumn. As a ground cover, “Snow Flurry” reaches heights of 4 to 6 inches and widths of up to one foot. With yellow centers, it has white daisy-like flowers that are hardy from USDA zones 3 to 9. “Jindai” can reach a height of three to four feet and has purple flowers with yellow centers that measure one inch in diameter. USDA zones 4 to 8 can withstand it. Although both of these asters prefer full sun, the “Snow Flurry” variety can be grown in a light shaded area.
Winter
Vining, hardy in USDA zones 6 to 11, the climbing aster (Ampelaster carolinianus syn. Symphyotrichum and Aster carolinianus) begins blooming in late summer In USDA zones 8 and up, it will continue to bloom well into the winter. The 2 inch-diameter pale purple or pink flowers have yellow to orange centers. Because they lack climbing tendrils, they can only be grown in full sun or partial shade.
Wisdom and Humor
- Scorpions were once scared away by the burning of asters, the September birth flower.
- Star-shaped flowers are what inspired the name “aster,” which is derived from the Greek word for “star.”
