Lesson 3
Growing & the Chelsea chop
In late May (the 'Chelsea chop' — the week of the RHS Chelsea Flower Show), cut perennial asters back by a third. They will flower a fortnight later but on shorter, sturdier stems and won't flop.
Stake taller varieties early with a few brushy twigs — by the time they need it, you've missed the moment.
Water deeply once a week in dry summers; asters in pots may need it twice. Drought stress is the trigger for mildew — keep them comfortable and they stay clean.
Year one of an aster
- 1March: plant from spring-bought 9 cm pots, into final position or 5 L container.
- 2April: water in well; mulch with compost around the crown.
- 3Late May (Chelsea chop): cut all stems back by one-third.
- 4June: insert brushy peasticks for support before the plant flops.
- 5August: deep water weekly; feed with high-potash fortnightly.
- 6September–October: flowering. Photograph; mark the colour for next year's plans.