Monty Don shares his simple tips for dividing herbaceous perennials

March is a time for new beginnings in the garden and, as TV gardening guru Monty Don explains, nothing likes a new start quite like a herbaceous perennial. And that, explains the Gardeners' World expert, means lifting and dividing them to give them a boost and create many more healthy new plants. 

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'It is worth doing this to all herbaceous perennials every three to five years,' writes Monty Don in this month's advice column on his website (opens in new tab). 

Herbaceous perennials are the reliable, dependable plants in our flower borders. They die right down to the ground in autumn and winter, but the roots remain alive and send up new stems and top growth in spring. They provide a wealth of flowers through the summer for seemingly little effort in return. 

To keep the new season's growth healthy and full of flowers, established herbaceous plants should be divided. 

And the time to lift and divide herbaceous plants is now, when the new growth is just starting to appear. 

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It couldn't be simpler to lift and divide herbaceous perennials and the rewards are well worth the small amount of effort. 

'Dig the whole plant up and discard the centre section to the compost heap, replanting the more vigorous outside parts of the plants in groups which will grow together to make one large plant,' writes Monty Don.

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'Dividing herbaceous perennials is part of the upkeep of any herbaceous border,' explains the presenter in a clip from Gardeners' World (opens in new tab) in which he demonstrates how to lift and divide vigorous Acanthus spinosus, chopping through it with a spade to produce multiple new plants that can be grouped or distributed throughout the garden. 

Perennial geraniums in particular divide up very readily, explains Monty Don, as he demonstrates how they can be gently pulled apart by hand. The new geranium plants can also be replanted in a group, 'which will give them new energy and new vigor and therefore much better flowering,' he says. Alternatively, he says, the new plants can be moved to another spot in the garden or shared with fellow gardeners. 

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From all the plants in your garden, how do you know what is a herbaceous perennial? They are the plants you find in most herbaceous borders, the perennial geraniums, delphiniums, salvias and heucheras, to name but a few.

Many herbaceous perennials will reappear each year for up to 10 years, others are more short lived and will last not much more than three years.

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However, the one thing every gardener can do to rejuvenate herbaceous perennials is to lift them and divide them. This will make a big difference to how vigorously the plants grow and flower, and it will even help restock the flower border, too. And if it's extra plants you're after, then you can divide herbaceous perennials more frequently – every two years is fine.