Now is one of the best times to get out and divide your perennials.
Some of you may well ask what that actually means. So, starting at the beginning – a perennial is a plant which lives for more than a year – often quite a long time in fact. Over the years these will get bigger and bigger as well as more congested so their roots don’t have the same space to take up nutrients and moisture. In order to keep them in good shape they need to be lifted and split into smaller pieces.
Not all perennials can be divided at this time of year – here’s the rule:
- Divide summer-flowering plants in spring (Mar-May) or autumn (Sep-Nov) when the soil is dry enough to work. In wet autumns, delay until spring. Spring is also better suited to plants that are a touch tender
- Many spring-flowering plants, such as irises, are best divided in summer (Jun-Aug) after flowering when they produce new roots
And this is how you do it:
First lift the clump gently with a garden fork, with plenty of space around to limit root damage (the RHS suggests doing this from the middle of the plant outwards but I find this often too difficult). Shake off excess soil so that roots are clearly visible.
What next? Well, that depends a bit on the growing habit:
Some plants, such as Ajuga (bugle), spread in a mat-like formation of individual plantlets which can simply be teased out and replanted with a space between each new plant.
Small, fibrous-rooted plants such as Heuchera and Epimedium can be lifted and pulled apart gently. This should produce small clumps for replanting, as shown above.
Large, fibrous-rooted perennials, such as Hemerocallis (daylily), require two garden forks inserted into the crown back-to-back. Use these as levers to loosen and break the root mass into two sections. Further division can then take place.
In some cases, a sharp knife, axe or lawn edging iron may be needed to cleave the clump in two (these are hostas shown above).
Plants with woody crowns like hellebores or fleshy roots like delphiniums require cutting with a spade or knife. Aim to produce clumps containing three to five healthy shoots.
And that’s it – all you have to do is re-plant where you would like them to flourish and sit back until next summer when you can gave something like the above. Just make sure that plants don’t dry out while they do re-establish and give them a little extra help by checking the slugs and snails aren’t on the attack.
