Why should I divide my perennials?
Because most perennials form clumps as they mature and, eventually, outgrow their space or lose vigour. Dividing them will increase stocks (giving you free plants to put elsewhere or give away) and revive tired or poorly flowering plants ensuring that your garden has healthy, vigorous plants that will continue to perform well.
Most summer-flowering perennials can be divided while the soil is still warm October-December (as long as the weather is mild and not too wet) or March-May as the plants come into growth again.
Our favourite perennials (to which we apply the lift and divide technique every year!) include peonies and baptesia australis. Here they are in all their glory (below). For a passionate gardener there’s nothing better than creating something for nothing!
How do I lift and divide my perennials?
You will need:
2 garden forks or an old knife
Compost or soil improver. We use peat-reduced composts such as those from The Greener Gardener
A container to transfer the cuttings
Dig a generous hole for each cutting – there should be plenty of room to spread the roots out
Fork a little compost or soil improver into the bottom
Getting down to it:
Loosen the soil round the plant and lift it carefully with as little damage to the roots as possible
Use 2 garden forks or an old knife to pull the plant into 2 or more sections, ensuring that each section has at least one growth tip or bud visible
Replant the sections as soon as possible taking care to plant them at the same level as the parent plant with their shoots above the surface of the soil
Mix in more compost or soil improver as you plant, taking care not to cover the crowns deeply (this is particularly true of peonies which hate to be planted too deeply or mulched)
Water them in well.
At this stage, it’s often useful to pop a plant support over the cutting so that you don’t put a fork through it while it is dormant and you’re not caught out come spring when it suddenly surges in size and starts to flop.
These are our favourites:
Care of particular plants
Hostas and other small fibrous rooted plants can be pulled gently apart with your hands instead of using a knife.
Larger fibrous rooted plants, such as agapanthus or asters, need two garden forks inserted back-to-back near the middle of the plant. Push the handles back and forth gently so that the prongs tease the plant apart.
Plants with woody crowns, such as hellebores should be cut with a spade or knife. I use a Japanese hori-hori, which combines the virtues of a knife and trowel.
Some plants, such as sedums, form an outer ring with a bare centre. Take your cutting from the outer, more vigorous growth and discard the centre of the old crown.
Traditionally used for peonies, Muntons’ two-ring supports or ‘peony baskets’ are perfect for plants whose stems may snap in strong wind or rain, or flop under their own weight. In the Winter border they add structure.
A final word
If your herbaceous border has been looking a little unruly of late, then it might be a good time to invest in some sturdy plant supports.
Muntons one-ring supports are perfect for catmints or any small herbaceous plants that have a tendency to flop.