Ornamental · Asteraceae
New England Aster
Symphyotrichum novae-angliae
Give it full sun and a midsummer pinch, and the New England aster lights up the fall garden when everything else is fading.
Full sun
USDA 4–8
3–7 ft · 0.9–2.1 m
Overview
The New England aster is a native perennial that saves its best for last. While the rest of the garden winds down, it erupts in purple, pink, and ruby daisies from late summer through fall. It belongs to the same family as sunflowers and daisies, and in the wild it turns roadsides and damp meadows violet in September.
This is a tall, fast-growing plant that wants room. Stems climb from 3 to 7 feet (90 to 210 cm) and the clump spreads steadily year after year, so give it a back-of-the-border spot in rich, moist ground. It shrugs off cold down to zone 4 and handles heavy clay better than most perennials.
Its real gift is timing. The flowers open just as monarchs head south and bumble bee queens fatten up for winter, making it one of the most important late-season nectar sources a garden can offer. Plant it once, pinch it in summer, and it comes back stronger every year.
Care
The short version: full sun, rich and steadily moist soil with good drainage, and a few pinches before mid-July to keep the tall stems from flopping. It blooms in fall and feeds the pollinators when little else does.
Light
Give it full sun for the most flowers and the sturdiest stems. It will take a little afternoon shade, but plants grown in too much shade stretch tall, lean over, and bloom far less.
Water
Keep the soil steadily moist, especially through dry spells, or the lower leaves drop and brown. It loves rich, damp ground and even tolerates clay, which suits a rain garden, but the drainage still has to be good to keep aster wilt at bay.
Soil
Plant in rich, fertile soil full of organic matter, from good loam to heavy clay. The one thing it won't forgive is standing water, so make sure the ground drains even when it stays moist.
Temperature
This is a tough, cold-hardy plant that handles -29°F to 95°F (-34°C to 35°C), thriving in zones 4 through 8. It dies back to the ground each winter and returns on its own in spring.
Humidity
Ordinary outdoor humidity is fine, so there's no number to chase. Air movement matters far more, since still, damp air around crowded stems is what invites powdery mildew.
Feeding
It needs very little. A light feed of balanced or compost-based fertilizer during the growing season is plenty. Go easy on the nitrogen, which only grows floppy stems that flop over.
Pruning
Pinch the stems back several times before mid-July to keep plants shorter, bushier, and less likely to need staking. After frost blackens the foliage, cut the whole plant down to the ground.
Size & spacing
Stems reach 3 to 7 feet (90 to 210 cm) tall, with each clump spreading 24 to 35 inches (60 to 90 cm) wide. Give them that full width so air moves through and mildew stays away.
When to plant
This aster runs on a fall clock. Set plants out in spring after the last frost or in early fall, pinch them back through early summer to keep them stocky, and the flowers arrive from late August into October.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Sow: Late winter to early spring; seed germinates more reliably after cold stratification
- Plant: Spring after last frost, or fall
- Harvest: August to October
Hardiness
USDA hardiness zones: 4–8
Temperature: down to -34°C
Troubleshooting
Most aster problems trace back to two things: damp, crowded conditions and unsupported height. Catch the early signs on the leaves and stems and you can step in before a clump goes downhill. Match what you see below, then act while it still helps.
Stems yellowing, wilting, and collapsing from the base up
A soilborne fungus called aster wilt is the culprit, and it strikes hardest in wet, heavy clay that never drains. There is no cure once a plant is infected, so dig it out and destroy it. Fix the drainage and don't replant asters in that same patch.
Fix:
- Remove and destroy severely affected plants
- Improve soil drainage
- Avoid replanting asters in the same spot
Dusty white film spreading across the leaves
This is powdery mildew, a fungus that takes hold when plants are crowded and air sits still, and it shows up worst in late summer. Pull off the coated leaves and skip overhead watering. Space and pinch the plants so air can move freely through the clump.
Fix:
- Improve spacing and air circulation
- Remove and discard affected foliage
- Avoid overhead watering
Tall stems leaning, splaying, or snapping
Rich soil and shade push these asters up past 90 cm (35 inches), and the lanky stems lean or split open after a rain. Pinch the plants back before mid-July to keep them shorter and stockier. Stake the tall ones early, or choose a compact cultivar that holds itself up.
Fix:
- Stake or support taller plants
- Pinch back stems before mid-July to reduce height
Toxicity
Good news for pet owners and parents. The New England aster is not toxic to cats, dogs, horses, or people, and the ASPCA lists asters as safe. A pet that eats a big mouthful might get a mild, passing stomach upset, but there is nothing poisonous to worry about.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats None
Safe around cats. A curious nibble might bring a little drool or a brief upset stomach, the kind any plant can cause, but nothing in the aster is poisonous.
Dogs None
No toxins here for dogs. A dog that chews a few flowers or leaves may get a passing bout of mild stomach upset and nothing worse.
Horses None
Horses can graze near it without harm. The plant carries nothing that poisons them, so a stray mouthful is no cause for worry.
Rabbits Safe
Rabbits can browse the foliage safely. Asters often turn up on lists of plants that backyard and wild rabbits eat without trouble.
Livestock Safe
Cattle, goats, and sheep can graze it with no risk of poisoning. The plant holds no compounds that would harm them.
Birds Safe
Birds are in no danger from this plant. Many feed on the seed heads through fall and winter, and the late blooms draw the insects they hunt.
People Safe
Not poisonous to people. It is grown as a garden ornamental rather than a food, so there is no reason to eat it, but handling it poses no risk.
Varieties
Most gardeners reach for a named cultivar bred for better color or a tidier habit. These three are the ones worth knowing.
Purple Dome
A compact, mounding selection that tops out near 2 feet of deep purple flowers and holds itself up without pinching or staking.
September Ruby (Septemberrubin)
Taller stems carry large ruby-red blooms with bright yellow centers.
Andenken an Alma Potschke
A vigorous, showy plant covered in bright rose-pink to salmon flowers.
How to propagate
New England aster is easy to multiply, whether you split an established clump or start fresh from seed.
DivisionEasy
Spring or early fall, every 2 to 3 years · One growing season
Division is the surest way to keep these asters going. Lift and split the clumps every 2 to 3 years in spring or early fall, and the divisions settle in within a single growing season. It rejuvenates tired plants, keeps the spread in check, and clears out the bare, dead center that old clumps develop.
SeedEasy
Sow in late winter to spring; may self-seed in the garden · Blooms typically the second year from seed
You can start plants from seed sown in late winter to spring, and a chill period beforehand greatly improves germination. Be patient, since seedlings usually wait until their second year to bloom. Plants often self-sow in the garden too, though the offspring can vary from the parent.
Myths
New England aster is toxic to cats and dogs like many fall flowers.
The ASPCA lists asters as non-toxic to cats, dogs, and horses. A pet that eats a big mouthful might get a mild, passing stomach upset, but nothing in the plant is poisonous.
This aster blooms all summer long.
It saves its show for the end of the season, flowering from roughly August into October. That late timing is exactly what makes it so valuable, feeding pollinators when little else is left in bloom.