IDEAL CANDIDATE: Hostas are perfect for division, their roots can be divided using a sharp spade, or teased apart by hand if you prefer (Image: Getty)
Autumn is an ideal time to propagate herbaceous perennials by division. These are the plants that die back to the ground in winter and return each spring. Dividing them not only encourages healthier, more vigorous growth but also gives gardeners an easy and cost-free way to increase their plant stock.
As temperatures begin to cool and rainfall increases, conditions become perfect for root development without the stress of summer heat. Dividing in autumn — typically from late September through early November — allows the plant sufficient time to establish strong roots before winter, ensuring a robust start when spring returns.
Not all perennials benefit from division at this time of year, however. The best candidates are those that flower in spring or early summer. These include popular varieties such as hardy geraniums, hostas, daylilies, lupins, phlox, delphiniums, and bleeding hearts.
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These plants have completed their flowering cycle and can be lifted and divided without interrupting their growth. Avoid dividing plants that flower in late summer or autumn, such as rudbeckias or asters, as they are best left until spring.
To begin the process, choose a mature, healthy plant — ideally one that’s been growing in the same spot for at least three years. Water it thoroughly the day before, which makes lifting easier and reduces stress. Carefully dig around the base of the plant using a fork or spade and gently lift the entire root clump from the ground.
Once lifted, shake or wash off excess soil to expose the roots. Using your hands, or for tougher clumps, a sharp knife or two garden forks, divide the root ball into smaller sections.
DIVISION BELLS: Perennials such as lupins, hardy geraniums, bleeding hearts, phlox, delphiniums, and day lilies are ideal for separating this time of year (Images: Getty)
Each new division should have a decent amount of root and at least one healthy growing shoot or bud. Remove any old, woody, or dead sections in the centre of the clump — they won’t regrow and can hinder the plant’s overall health.
Replant each division as soon as possible. Place it back into well-prepared soil enriched with compost or well-rotted organic matter, ensuring it sits at the same depth as it did originally.
Gently firm the soil around the plant and water it thoroughly. While you may not see much growth above ground before winter, the plant will be quietly settling in and developing roots.
Useful items for dividing plants
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Mulch: A 9kg bag of Strulch Organic Garden Mulch costs £12.59 at Crocus. Made from wheat straw, it protects roots, reduces weed growth and deters slugs and snails.
Digging fork: This Spear & Jackson Traditional Stainless Steel Digging Fork is popular with Amazon shoppers who appreciate the value for money. It costs £26.
Ratchet secateurs: The Bulldog Ratchet Secateurs are £14.98 at Toolstation. The ratchet system increases hand strength by two or three times, ideal for those with arthritis.
Sharp knife: This Kingswood Green Folding Horticultural Grafting Knife features a razor-sharp blade designed for accurate cuts; ideal for grafting, budding, and pruning tasks in the garden. Price: £8.99.
Prices correct at the time of publication.
In the weeks following, keep the soil moist but not waterlogged. Avoid feeding the plants until spring, when they begin to show new growth. If the weather turns dry, continue to water, especially if the soil is light or sandy.
Autumn divisions should be completed at least four to six weeks before the first hard frost, allowing the plants time to establish. If you’re dividing later than this, it’s better to pot up the divisions and keep them under cover in a cold frame or sheltered spot, then plant them out in the spring.
Dividing perennials in autumn not only helps maintain the vigour and longevity of your plants, but also refreshes overcrowded borders and creates new planting opportunities. With just a little effort now, your garden will reward you with healthier, fuller displays when spring arrives.
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