The perennial problem.
As perennial plants mature they can start to look congested and tatty, fighting for space with their neighbours and dying out in the centre whilst all the healthy growth is around the outside. Most perennials benefit from being lifted and divided every three or four years. As well as rejuvenating the plants it’s a great way to increase your stock.
When to divide
The old-fashioned rule is if it flowers before Midsummer’s Day you should divide it in autumn, and if it flowers after Midsummer’s Day you should divide in spring. There are exceptions, but generally you need to divide when there are clusters of new leaves pushing through the soil (if you wait until the leaves have opened out there’s a bigger area for water loss and your new plants are more likely to wilt and take longer to establish)
How to divide
- Arm yourself with a couple of garden forks, a spade and a plastic sheet
- Carefully dig out the clump you want to divide and lift it onto the plastic sheet. If the clump is too heavy to lift use the spade to slice sections out of it
- Split the clump into several pieces. You might be able to pull the clump apart with your hands or with the garden forks, but woody rootstocks will require a knife or saw. Each piece needs its own shoots and roots
- Replant the best bits at the same depth as they were before, after working some compost and slow-release fertiliser into the ground.Water well and remember to keep watering until the roots are well-established
Bulbs need to be divided for similar reasons. Many are excellent at multiplying themselves and, over time, clumps become overcrowded and flowering declines because of the heavy competition for nutrients. Snowdrops and Winter Aconites in particular must be divided ‘in the green’ – straight after flowering, and most other bulbs can also be dealt with whilst the leaves are still growing vigorously. Crocus, Daffodils and Grape Hyacinths will all divide well in March.
- Lever the clump out and gently rock and twist the bulbs back and forth until they separate.
- Don’t allow the bulbs to dry out during transplantation – cover them with wet newspaper while you work
- Replant clumps into well-prepared and fertilised soil at the appropriate depth.
- Mulch and water