Aster novi-belgii — the Michaelmas daisy many of us grew up with — is having a quiet renaissance. Renamed Symphyotrichum novi-belgii by botanists but loved by gardeners under its old name, it delivers sprays of daisy-like flowers from late August well into October, just as most of the border is winding down. Plant it in spring, give it a sunny spot and soil that stays moist but never waterlogged, and it will settle in comfortably before its first autumn performance.

Choosing the Right Spot and Soil

These are meadow plants at heart, and they resent two things above all: drought at the roots and stale, humid air around the leaves. Powdery mildew is the classic complaint, and it almost always traces back to one of those two problems.

Pick a position in full sun — six hours or more in midsummer — with a bit of room for air to move through the clump. A spot that catches morning sun is ideal, because it dries dew off the foliage early. Soil should be fertile and moisture-retentive but free-draining; a loam that holds water like a wrung-out sponge is perfect.

• Heavy clay: fork in garden compost and a handful of grit per square metre to open it up.
• Light sand: dig in plenty of well-rotted manure or compost before planting to hold moisture.
• Containers: perfectly workable, but use a loam-based compost and never let the pot dry out in August.

Avoid planting directly under eaves or against a south-facing wall where rain never reaches. If you have had mildew on asters before, choose a resistant cultivar, and space plants generously — around 45cm apart for tall types, 30cm for compact ones.

Planting in Spring, Before the Season Runs Away

Spring planting gives roots the whole growing season to establish, so the plant flowers properly in its first autumn rather than sulking. April to mid-May is the sweet spot in most of the UK; wait until hard frosts have passed but don't leave it so late that the plant has to cope with dry June weather while still rooting.

Prepare the ground a fortnight ahead if you can, forking it over and mixing in two or three spadefuls of garden compost per square metre. Add a slow-release general fertiliser at planting time — blood, fish and bone at roughly a handful per plant is plenty.

Dig a hole wider than the rootball but no deeper. Set the plant so the crown sits level with the soil surface; burying it deeper invites crown rot over winter. Backfill, firm gently with your heel, and water in well even if rain is forecast. A mulch of compost or bark chippings, kept clear of the stems, will hold moisture and suppress weeds through summer.

If you are planting bare-root or mail-order divisions, soak the roots for an hour before planting and water every few days for the first month.

Pinching, Staking and Summer Care

Tall varieties reach 90–120cm and will flop the moment a heavy shower arrives. Two simple jobs sort this out.

First, pinch. In late May or early June, nip out the growing tips of each stem with your thumb and forefinger. This encourages branching, giving you a bushier plant with more flowers and shorter, sturdier growth. Repeat once more in early July if you want a really compact clump — the flowers will come slightly later but be far more numerous.

Second, support early. Push twiggy pea sticks or a grid of garden string over the clump while it is still short, so the stems grow up through it. Trying to stake a collapsed aster in September is miserable work and rarely looks natural.

Water deeply once a week in dry spells rather than little and often, and always at the base rather than over the leaves. Feed with a potassium-rich tomato feed from midsummer to encourage flower bud formation.

Copper-Toned Foliage and Autumn Pairings

Part of the aster's charm is that its own foliage shifts as nights cool, taking on bronze and copper tints that echo the season. Lean into that. Plant it beside companions with copper or russet leaves and the whole border warms up as the light softens.

• Heuchera in caramel or amber tones, catching the low sun at the front of the border.
• Bronze fennel, whose feathery foliage and height make a lovely veil behind the flowers.
• Sedum with dusky pink flowerheads and red-tinged leaves.
• Grasses such as Molinia or Deschampsia, whose straw and copper seedheads catch every passing breeze.

Cooler blues and purples — salvia, catmint, hardy geraniums — provide contrast and extend the season either side of the asters' peak.

Border Care Through Autumn and Winter

Deadhead spent flowers to keep fresh buds coming, but leave the last seedheads standing for the birds and for structure through the first frosts. Once stems blacken and collapse, cut the whole clump back to about 15cm. On heavy, wet soils, do this in late autumn to reduce the risk of crown rot; on lighter ground you can leave it until March.

Every two to three years, lift and divide congested clumps in early spring. Discard the woody centre, replant the vigorous outer pieces, and water them in. This keeps plants flowering freely and stops mildew taking hold in crowded stems.

Slugs are the main pest on young spring growth — a night patrol with a torch is more effective than any pellet. With that small attention, a well-sited aster will reward you with colour long after the rest of the border has called it a day.