My Asters are about two feet tall, should have pruned them back earlier. How low can I prune them and still have good heads in the fall?
Asters can be treated much like mums and pinched several times before 4th of July. Pinching after mid July may delay flowering. Or just cut asters back by one half in early to mid June. Asters can get tall and floppy so pinching or cutting back may reduce the need for staking.