Lesson 6
Through the year — division and renewal
Asters reward division every 3 years. The middle of the clump dies out; split it in spring, replant the outer pieces in fresh compost. This single act keeps a plant going for decades.
In late autumn, cut stems back to 10 cm once flowering ends. Leave the seed heads on for a few weeks if you can — goldfinches strip them.
Container asters benefit from a fresh-compost top-up every spring — scrape off the top 5 cm and replace with new compost + slow-release feed.
Save 3 stems' worth of seed each autumn from your favourite open-pollinated aster. Sow them next March; you'll have 30 new plants in 9-cm pots by May, ready to give to gardening friends or plant a whole new drift.