Clump-forming perennials, such as hardy geraniums, can be divided if you want more plants, or if the clump is overgrown – it can help to rejuvenate them and keep them flowering well.
Dividing involves splitting an established plant into several pieces, each of which has a section of the roots.
Watch our video guide to dividing hardy perennials.
When planting your new plants, help them get off to a flying start by working in well-rotted organic matter and fertiliser into the new area, then firm and water in well.
Take a look at some of the plants to propagate by dividing after flowering, below.
Lamiums are tough shade-loving perennials form mats of evergreen foliage, with flowers in summer. They make great ground-cover plants, so dig up and divide, then replant where cover is needed.
Silver, green and yellow variegated foliage of Lamium maculatum ‘Dellam’
Tough and reliable, rudbeckias provide spectacular fountains of colour from summer and into autumn. By splitting the clumps, you can dot new colourful plants about the garden and rejuvenate the original plant.
Golden-yellow flowers of Rudbeckia ‘Little Gold Star’
The popularity of bergamot with bees and other pollinators is just one of the many reasons to propagate them. Divide these vigorous plants to improve their flowering performance and keep large clumps from spreading too far.
Bright red blooms of Monarda ‘Cambridge Scarlet’
Stachys, or lambs’ ears, will gradually spread to form large assemblages of silvery foliage, with purple-pink flowers. They’re drought-tolerant and are brilliant wildlife-friendly ground-cover plants.
Silver, furry foliage of lamb’s ears, with small mauve flowers
By diving up your hardy geraniums, you’ll be rewarded with a bounty of vigorous new plants. If you find you have a surplus, simply pot up spare divisions and give to friends or family.
Mauve flowers of hardy geranium ‘Ballerina’
These versatile plants can be divided up once they’ve finished flowering, to be replanted under trees and shrubs or in containers. Ajuga is another fantastic evergreen ground-cover plant.
Small blue ajuga flowers
Asters, such as Symphyotrichum novi-belgii ‘Royal Ruby’ (pictured), will flower less prolifically over time, so it’s worth dividing them every few years.
Video: How to divide asters
Hot pink aster flowers
If you’ve missed the boat for autumn division, don’t worry. All the plants above can also be divided in spring, before they flower, giving them a near whole season to settle in and establish.