Dividing Perennials: A Beginner’s Guide

Lifting and dividing perennials helps rejuvenate older plants and gives you spare plants to expand your garden. Don’t worry about killing your plants – we’ll teach you how to divide perennials easily and safely.

Dividing perennial plants helps keep your garden thriving. Most perennials benefit from being divided every couple of years, and it’s also a great way to add new plants to your garden for free. It may feel daunting digging up and hacking apart your precious plants, but don’t worry – they’re more resilient than you think!

You can also divide new plants before you plant them out. Rather than buying several plants in 9 cm pots, buy a larger plant in a 3-litre pot and divide it up. This can be more cost-effective if you’ve got a large space to fill.

Do you need to divide perennials?

Most perennials are fine for the first couple of years after you plant them. But after a time, many begin to spread and their roots become congested. This can affect the plant’s ability to take up nutrients and water from the soil. Dividing the plant prevents it from taking over your garden and gives the roots better access to nutrients.

Dividing a large perennial also gives you more new plants for your garden. These can be used to replace older perennials, which aren’t flowering as well as you’d like, or fill a new bed or pots with plants. Dividing plants is a form of propagation, meaning each section you replant will be genetically identical to the parent plant.

What perennials can be divided?

Many clump-forming perennials, like daylilies (Hemerocallis), asters, hostas, ornamental grasses, hardy geraniums and irises, need to be divided every few years. You can also divide spring-flowering bulbs, primroses (Primula), rudbeckias, heleniums, bergenias, agapanthus, crocosmia, sedums, heucheras and euphorbias.

That’s not an exclusive list – most herbaceous perennials can be divided, though some are more sensitive to being moved and may not recover as quickly. Peonies and hellebores fall into this category.

Perennials with a long taproot, such as lupins and oriental poppies, are more difficult to divide successfully. Woody herbs like lavender and rosemary are best propagated by taking cuttings rather than attempting to divide the plant.

When to divide perennials in the UK

The best time to divide perennials is in the spring or autumn, as this is when most plants are dormant. Spring is a better time to divide tender plants like agapanthus and anemones, so they have plenty of time to recover before winter. Hostas also tend to do well if divided in the spring, though you can also divide them in autumn.

The exception to this rule is spring-flowering plants such as irises. It’s best to divide and replant irises in summer, after they’ve flowered, as this is when they produce new roots. You can also lift and divide spring-flowering bulbs like crocuses, snowdrops and daffodils once they’ve finished flowering.

How to divide perennial plants

Follow these four steps to successfully divide your perennials:

Step 1: Dig up the plant

Use a garden fork or spade to lift the plant while trying to avoid too much damage to the root system. Depending on what plant you’re digging up, this may be a simple task or a back-breaking nightmare. If it’s the latter, then take comfort from the fact that your plant is likely robust enough to survive whatever attacks you make on it while getting it out of the ground.

Shake off any excess soil and trim any dead leaves or stems.

Step 2: Tease/tear/slice the roots apart

Now, it’s time to tease the roots apart – or go at the fibrous mass with a carving knife. The amount of effort required will depend on the type of plant and how big it’s grown. Here are a few tips:

• Smaller plants with fibrous roots, such as hostas, lungwort (Pulmonaria), primulas and heucheras, can be pulled apart.

• Larger, more established fibrous plants will require the two-fork method: insert two garden forks, back to back, into the crown of the plant and use them to lever the roots apart.

• If the fork method doesn’t work or you want to make smaller divisions, then try using a sharp knife or axe to split the clump.

• Use a sharp spade or knife to slice through fleshy-rooted plants and those with woody crowns. You should use a spade to divide large hosta plants, hellebores and peonies.

• Crocosmia and dierama produce chains of corms. When lifting them, dig down 30 cm to avoid damaging the corms. Divide and replant chains of corms.

Step 3: Replant immediately

It’s important to replant your divided plants as soon as possible to prevent the roots from drying out. Check planting guidelines for new plants to give you an indication of how much space each plant needs, and give the soil a nutrient boost by adding compost, other organic matter or fish, blood and bone fertiliser. As for where you plant them, you have a few options depending on the size of your garden, how much free space you have and how much you love the plant!

Option 1: Plant in the same area 

When it comes to planting, one may be lonely, two is company, but three is most definitely not a crowd. Grouping plants in clusters of three or five is a common garden design principle, as it gives a natural, balanced look to your bed. You could replant divided sections together (leaving space around each plant for it to grow) or intersperse them with other plants.

Option 2: Move to a new part of the garden

You can move the entire plant if you didn’t like its original location or replant one division in the same place and the others elsewhere in the garden. With a bit of patience, this can be a low-cost way of creating the garden of your dreams.

Option 3: Pot them up

If you don’t have anywhere in your garden to plant the divisions immediately, then put them in a good-sized pot of compost. You can either keep the plant in the pot temporarily, if you know you want to plant it out in the future, keep it as a container plant (if suitable) or, if you know you’re not going to have space for it, donate it to a friend, neighbour or local community garden. If you’re dividing perennials in autumn, overwinter pots in a frost-free location.

Step 4: Water well

Wherever you’re planting your divisions, water them in well. Your plants will need regular watering to help them develop healthy root systems. Lack of rain generally isn’t an issue in the UK in spring and autumn, but if there is a long dry spell, get out your watering can and give them a drink.

FAQ

What’s the best time to divide perennials?

Most perennials are best divided in the spring or autumn. Spring is a good time for tender plants like agapanthus and anemones, as well as hostas and autumn-flowering perennials. Some spring-flowering plants, like irises, are best divided in summer, after they’ve finished flowering.

Can you divide perennials in autumn?

Early autumn is a good time to divide many herbaceous perennials, as it gives the divided plants time to get established before winter. You want to wait until after the plant has finished flowering, so you may want to wait and divide late-blooming plants in spring. If it’s a very wet autumn, it may also be better to wait until spring to avoid planting in soggy ground. 

How do you divide a hosta plant?

You may be able to tease apart small hosta plants with your hands. Divide larger plants using a sharp spade to slice the clump of roots apart. Replant the sections immediately.

How do you divide a rhubarb plant?

You should divide rhubarb crowns in winter or early spring, while the plant is dormant. Dig up the crown and use a spade to divide it into sections. Make sure each section has at least one bud and part of the rhizome. Replant each division as soon as possible.