Dividing perennials

by Adam Pasco

When did you last lift and divide congested clumps of perennial flowers in your garden? You're not alone if you're struggling to remember [...]

Close-up of Adam Pasco replanting a newly divide clump of geraniumWhen did you last lift and divide congested clumps of perennial flowers in your garden? You're not alone if you're struggling to remember, as this is a job I often overlook too.

Hardy perennials just do their thing year after year, and I don't give most of them a second thought. Well, that's why I planted them in the first place – to be reliable performers that look after themselves.

The problem with leaving perennials alone is that the central parts of plants grow less productive over time, with new shoots spreading outwards from the fringes. The soil they're growing in gets more impoverished as its nutrients become exhausted.

So, what can be done? I do spread a good mulch of compost over the soil around them each year, and this is gradually taken down by worms to improve the soil. At this time of year, when perennial plants are putting on such a burst of new growth, I also make sure they don't go short of water. Adding a liquid feed a couple of times a year also helps.

It has been an incredibly dry spring in my part of the East Midlands, with hardly a drop of rain for months. Farmers and gardeners are getting desperate for a good deluge, and I can openly make that plea now the long holiday weekends are over.

The other thing we must all do from time to time is to lift and divide our plants. Large, congested clumps need gently lifting completely, like with my hardy geraniums, hostas, phlox, campanula and others.

Healthy, young outer portions can be teased or cut away to be replanted into freshly dug and improved soil, while the very old central portions of clumps can be discarded.

This helps maintain youthful vigour in your borders, resulting in strong growth and great flowering performance.

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Gardeners' World Web User 03/05/2011 at 10:33

I find I have to lift and divide primulas at least every third year else they disappear altogether. I open to "my public" for the very first time tomorrow so it can bucket down with rain from Wednesday night onwards. Wish me luck everyone, as I do want to show that gardening is a healthy,happy, useful thing for an octogenarian to indulge in.

Gardeners' World Web User 03/05/2011 at 10:54

Thanks happymarion, and wishing you a really enjoyable garden opening. I'm sure you've been very busy preparing, so I've no doubt your garden is looking stunning! I know we're desperate for rain, but I'll refrain from the rain dance until the end of the week to avoid soaking your visitors. And yes, primulas are another perennial that benefits from regular lifting and dividing. It's amazing how many new plants you'll produce to give away too.

Gardeners' World Web User 03/05/2011 at 11:01

It's to rain from thursday onwards, so a little relief for gardeners. I have only been gardening for 3 years and I'm a bit nervous over lifting and dividing in case I do the wrong thing. I have a large clump of Aquilegia's. Do I divide them while growing or in the winter?

Gardeners' World Web User 03/05/2011 at 11:14

When is the best time to divide phlox. I have two or three huge mounds which look great now - can I split them now or should I wait?

Gardeners' World Web User 03/05/2011 at 13:03

Reply to Boabd: I've always found Aquilegia (columbine) to be quite short-lived, so have never divided them. However, I do let them set seed, and seedlings pop-up everywhere. These can be lifted and transplanted to a better position at any time. Reply to Carla: Yes, phlox just spreads, and can become quite invasive as it outgrows its 'allotted' space. It's probably a bit too tall to lift and divide now. I'd usually do this in February/March, before shoots start forming, which would be damaged during division. However, this could be done in autumn in milder districts and those on light, free-draining soil. If I were you Carla I'd enjoy them this year and divide them early next year.

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