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, talll sedums, oriental poppies,, hardy salvias and otherr clump-forming perennials.
Vigorous clump formerss such as Rudbeckia fulgida, pictured right, Achillea and spring-blooming pulmonariass may benefit from beingg divided every second year.
Border chrysanthemumss will also produce betterr quality flowers on stockyy stems if divided frequently.
Creeping or ground- coverr perennials may spread further than you want, so keep them within bounds. Tall Japanesee anemones, spreadingg cranesbills, Ajuga, Lamiumm and other ground cover plantss can be left to their ownn devices for several years. Butt even they may benefit fromm having old plants removed.