It’s time to split clumps of asters and chrysanthemums

THIS is a good time to overhaul your planting if you have borders or mixed permanent planting anywhere.

Vigorous perennials can spread more widely than you want, perhaps smothering less rugged plants. ageing perennials can also lose vigour if not lifted and split.

Dig out any clump-forming plants that have become too large. Break them down, removing from the outsides of the clump. Those are the youngest and most healthy parts of the plant.

Make sure each division has roots and shoots. Plant them where you want them to flower over the next few years.

This applies to perennial asters, border phlox, tall sedums, oriental poppies, hardy salvias and other clump-forming perennials.

Vigorous clump formers such as Rudbeckia fulgida, pictured right, achillea and spring-blooming pulmonarias may benefit from being divided every second year.

Border chrysanthemums will also produce better quality flowers on stocky stems if divided frequently.

Creeping or ground-cover perennials may spread further than you want, so keep them within bounds. Tall japanese anemones, spreading cranesbills, ajuga, Lamium and other ground cover plants can be left to their own devices for several years. But even they may benefit from having old plants removed.