Japanese aster vs New York aster

Japanese aster and New York aster are often considered for the same spot in the garden (flowers, pollinator friendly). The data below shows where they differ: size, hardiness, care, toxicity and price.

Japanese aster

Aster ageratoides 70 cm × 60 cm after 10 years

A very tough, late-flowering aster: from late summer until the frosts it is covered in a haze of pale lilac, white or pinkish flowers, in sun or…

Perennial

Full sun

Part shade

from about CZK 71

New York aster

Aster novi-belgii 1.2 m × 90 cm after 10 years

A tall, upright perennial that is covered in violet, blue, pink or white daisies from late summer to mid autumn, when little else is in flower, and…

Perennial

Full sun

Part shade

from about CZK 110

Key differences

New York aster: It may be planted in a garden, but it is on the Hungarian list of invasive species: it may not be planted on public ground and can escape from gardens, so plant it only with care, away from natural habitats. Powdery mildew is the main problem: by late summer the leaves are often coated grey and wither from the base up, especially in dry soil and crowded, airless spots.
New York aster grows larger: 1.2 m × 90 cm after ten years, against 70 cm × 60 cm for Japanese aster (an estimate: sources differ).
New York aster is hardier: down to -34 °C, against -23 °C for Japanese aster.
Japanese aster tolerates drought better than New York aster.
Japanese aster needs less care than New York aster.
Japanese aster is cheaper: about CZK 71 at the size usually planted, against about CZK 110 for New York aster.

Which one to choose?

Japanese aster is the safer choice: New York aster can escape from gardens, so plant it only away from natural habitats.

Watch out for

Japanese aster

In good soil the rhizomes run quickly and crowd out weaker perennials. Powdery mildew can appear in persistently hot, dry spots, although it is far more resistant than Michaelmas daisies. Slugs and snails may chew the young shoots.

New York aster

Powdery mildew is the main problem: by late summer the leaves are often coated grey and wither from the base up, especially in dry soil and crowded, airless spots. It spreads by rhizomes and by seed, the clumps need dividing every few years and tall cultivars can flop without support. In Central Europe North American asters have escaped from gardens and formed large stands along rivers and on floodplains, where they crowd out native plants; Hungarian nature conservation counts them among the invasive plants and in Switzerland the species group may not be sold. Cut down the spent stems and never dump dug-up clumps or rhizomes in the wild.

The data side by side

Feature	Japanese aster	New York aster
Group	Perennial	Perennial
Size after 10 years	70 cm × 60 cm (uncertain)	1.2 m × 90 cm
Ultimate size	0.4–1 m × 30–60 cm (uncertain)	0.9–1.5 m × 30–90 cm
Growth rate	Fast	no data
Light	Full sun, Part shade	Full sun, Part shade
Soil	Average garden soil, Clay, Sandy, Calcareous	Average garden soil, Clay, Sandy
Hardiness	down to -23 °C (USDA 6, RHS H7)	down to -34 °C (USDA 4, RHS H7)
Heat tolerance	Medium (uncertain)	no data
Foliage	Deciduous	Deciduous
Flowering	August–November, purple, white, pink	August–October, purple, blue, pink, white
Water need	Medium	Medium
Drought tolerance	Medium	Low
Maintenance	Low	Medium
Planting distance	40 cm	50 cm
For dogs	Non-toxic (uncertain)	Non-toxic (uncertain)
For cats	Non-toxic (uncertain)	Non-toxic (uncertain)
For children	Non-toxic	Non-toxic
Typical price	approx. CZK 71	approx. CZK 110

Prices are rounded, indicative values. Toxicity data is for information only. If your pet or child has eaten a plant, contact a vet or a doctor. Data updated: October 17, 2026

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