Once perennials have finished flowering, you can lift well-established clumps, or any plants that are starting to go bare in the centre, and divide them. Autumn division is best suited to perennials that flower in early summer.
Autumn division not only makes new plants, it reinvigorates old, tired clumps. If any perennials aren’t flowering as well as they used to, or have simply got too large for their space, lift and divide them. But don’t feel you have to divide perennials – many can be left to grow healthily for years before it becomes necessary.
Summer-flowering perennials such as delphiniums and daylilies are best divided now, but if autumn weather is wet and cold, or you have heavy clay soil, it is better to wait until spring. You should also wait until spring to divide tender perennials.
How do you do autumn division?
Follow our step-by-step guide to autumn division:
- If the weather has been dry, water the perennials well the day before you intend to divide them.
- Use a fork or spade to lift the entire clump, bringing its whole rootball up and out of the soil.
- Many wiry-rooted plants divide well using the back-to-back fork method. Push two forks into the centre of the clump, back-to-back, then pull the handles in opposite directions to prise the clump apart. Repeat the process to produce more divisions if necessary. If the clumps are relatively small, you can often do the job with your hands.
- Plants that have more woody roots, such as daylilies, may need to be sliced into smaller portions using a knife or a sharp spade.
- Dig organic matter into the soil before replanting the divisions in groups.
What other plants can I divide in autumn?
As a general rule, if it flowers before the longest day (21 June), it’s a good candidate for autumn division. Try it with perennials such as bleeding heart (dicentra), lily of the valley (Convallaria majalis), hardy geraniums, primulas, daylilies (hemerocallis), herbaceous peonies and veronica.
Don’t forget to sign up for our monthly The English Gardener newsletter, bringing you all the practical gardening advice you need throughout the year. Sign up on the right of this article.
Need plants or gardening kit? Visit our directory of suppliers.