The Well-Tended Perennial Garden The Essential Guide to Planting and Pruning Techniques, Third Edition

Symphyotrichum

novae-angliae

(syn. Aster novae-angliae)

New England aster

compoSitae

1 1/2-in. purple, pink, or white daisy flowers;

hairy dark green foliage

3–6 ft. high; 2–3 ft. wide

Full sun

Blooms August–October

Zones 4–8

pruning Deadhead or cut plants

completely to the ground after

flowering to prevent growth of

seedlings, which do not develop true

to cultivar type. Cutting plants to the

ground can often come as a relief,

because foliage may blacken or

deteriorate due to foliar diseases such

as powdery mildew. Do not compost

infected clippings. Tall-growing forms

of New England aster respond well to

pinching or cutting back to reduce

height, eliminating the need for

staking. Such pruning usually

produces more flowers per plant as

well. Asters can be treated like mums

(Chrysanthemum ×morifolium) and

pinched several times before mid- to

late July. Pinching into late July will

usually delay flowering. A

lower-maintenance approach is to

simply cut asters back once by half to

two-thirds, depending on the ultimate

size of the plant and the gardener’s

objectives, in early to mid-June. Plants

can be anywhere from 12–24 in. tall at

the time of pruning. Pruning again

later can delay flowering, and the floral

display may be slightly reduced.

Asters cut back by half in mid-June and

then cut back by half again in mid- to

late July will flower 2 weeks later than

plants pruned only once, and they will

flower at 18 in. rather than 3 ft. Plants

cut back twice in this way were full and

nicely formed, with what appeared to

be just a minor reduction in the

number of flowers.

Plants can be shaped by cutting the

outer stems lower than inner ones and

thinned at the same time as they are

initially cut back. Thinning is often

recommended to improve the overall

form of the plant and to increase the

air circulation around the plant in the

hope of reducing foliar diseases that

often affect asters. Thin asters by

about a third or more, removing the

weakest stems and leaving about 1 in.

between stems. Personally, I have not

seen much improvement in the plants’

resistance to disease with thinning,

but thinning does make room for

branching of pruned or pinched stems.

Shaping for lower outer branches

can help hide the ugly legs that are

often associated with asters.

Symphyotrichum novae-angliae
‘Barr’s Pink’