Blue wood aster

Questions about blue wood aster

Does blue wood aster need sun or shade?

Blue wood aster grows in part sun (4 to 6 hours of sun, including some afternoon sun), part shade (2 to 4 hours of sun, mostly in the morning) and shade (less than 2 hours of direct sun, or bright dappled light).

It wants ordinary well-drained soil, of average fertility, and a good soak in dry spells.

What zones does blue wood aster grow in?

USDA zones 3 to 8. It is hardy to zone 3, which means it survives winter nights down to about −30 °F (−34 °C).

Above zone 8 it struggles: the zones measure winter cold, but a plant's top zone usually means the summers are too hot or the winters too mild for it to rest.

Gardening in Canada? Use the USDA zone for your town: Canada's own zone map uses different numbers.

When does blue wood aster flower in my zone?

In zone 5 it flowers mid September to mid October. As an autumn flower it keeps much the same dates in every zone: it answers to shortening days and cool nights more than to the warmth of spring.

Worked out from Hopkins' bioclimatic law: spring arrives about four days later for each degree of latitude north, and one zone is roughly two degrees. A warm spring or a cold one moves any garden two weeks either way.

How far apart should blue wood aster be planted?

18 in (45 cm) apart, from the middle of one plant to the middle of the next. That is a little closer than its full width of 24 in (60 cm), so a group knits into one patch.

It grows 3 ft (90 cm) tall. Give it the full distance from anything taller, or it will lean out towards the light.

How many blue wood aster plants do I need?

At 18 in apart, set out in staggered rows:

• 5 to fill 10 square feet (about 1 m²)
• 7 for a single row 10 ft (3 m) long
• 17 to fill a 4 × 8 ft bed on its own

In a mixed border, plant it as a group of three or five, with a second group further along in the other number.

In the bed above, the planner used three in one group.

Is blue wood aster poisonous to dogs and cats?

No toxicity is recorded for dogs, cats, horses or people, according to NC State Extension.

"Not toxic" is not "edible": a pet that eats a lot of any plant can be sick.

Do deer eat blue wood aster?

Mostly not. NC State lists it as resistant to deer. No plant is proof against a hungry deer in a hard winter, but this one is low on the menu.

Will blue wood aster spread?

It seeds itself about; the risk of it taking over is moderate. Self-seeds freely. Remove the spent flowers to limit seedlings.

What flowers after blue wood aster?

Blue wood aster is over by mid October. These start as it finishes and carry the same spot on, so it never goes flat:

• Bodnant viburnum 'Dawn': from early November to late December, 10 ft tall.
• Common witch hazel: from mid October to late November, 15 ft tall.

What does blue wood aster look like in winter?

Blue wood aster dies down, but leave the stems standing: the seed heads stand through the winter, and songbirds eat the seed. Cut them down in early spring, before the new shoots come.

Is blue wood aster good for bees and butterflies?

Blue wood aster is visited by pollinators, bees, specialist bees, butterflies and songbirds.

It is a host plant: the caterpillars of pearl crescent feed on its leaves. A butterfly can only lay its eggs on its host plants, so these do more for it than any nectar flower.

It is native to the United States and Canada.