How to divide plants: splitting herbaceous perennials the easy way

5 minutes read

Long before online shopping and plants by mail; splitting and dividing plants was one of the best ways of propagating your garden plants. It’s also been used for years as a way to help share and spread plants amongst communities without having to grow new plants slowly from seed.

Furthermore, by getting down and dirty when dividing plants you really get to understand how your plants grow and what their preferences are!

What plants can I divide?

Herbaceous perennials are easily split and multiplied via division. They usually form a set of fibrous roots which can be easily divided or cut to form a new set of identical plants. The herbaceous perennials are plants that come back year after year and die back to the ground at the end of each growing year. For other shrubs, trees and plants that don’t follow this cycle, you may need a different method for propagating them such as via a cutting or by sowing seeds.

alt — Rudbeckias are super easy to divide for a riot of colour!

Here are a few common examples of herbaceous plants that can be easily divided:

Agapanthus
Anemone
Aster
Bergenia
Convallaria
Crocosmia (these are a corm so division is done manually by teasing clumps of them apart never by slicing in early Spring only)
Delphinium
Epimedium
Eryngium
Euphorbia (always wear gloves as their sap can be an irritant)
Geranium
Helianthus
Hemerocallis
Hosta (usually with a sharp spade to split the crown)
Lychnis
Lysimachia
Ornamental grasses (Miscanthus, Molinia, Calamagrostis)
Primula
Rudbeckia
Salvia
Sedum
Verbena

alt — Hostas look wonderful when planted en masse, so why not split them for even more?

Why divide plants?

The first obvious answer is that dividing plants helps multiply the number of potential plants you have in the garden. Rather than one plant reaching maturity and then sitting there lazily, it encourages multiples of this parent plant to spread out and help provide even more interest in your garden.

If you’ve read my other planting guides you will know how repetition in flower bed planting schemes is key. Splitting plants and dividing them is a really cheap way to do this at home without spending a penny!

Dividing plants also helps to keep herbaceous perennials in far better health. It helps stop them becoming unproductive (where plants may become lacklustre or show a reduction in the flowering capacity year on year) as it encourages vigorous new regrowth in plants. So it really is win-win.

alt — All of these beauties can be easily divided to create more plants for free!

How to divide plants

Dividing plants is not as daunting as you may think. You will need the following equipment for dividing plants easily.

Garden fork or trowel
Sharp knife
Secateurs or sharp scissors
Gloves
Watering can

1.The first thing to do is loosen the soil around the plant you want to divide. I always dig a good 3 inches or so wider than the base of the plant as the roots will spread out far further than the plant. Take your time and work around the herbaceous perennial.

alt — This hosta is best divided with a spade than by hand, it’s quicker and cleaner for the plant

2.Carefully lift the plant out of the ground and lay it down. Have a good look at the root structure. Is it congested and knotted or relatively easy to loosen? If it is easy to loosen then you can carefully pull and tear the plant apart. The aim is to divide the plant either using your hands, a sharp knife or even a spade if it’s got a thick crown like a Hosta or Ornamental grass.

alt — These Rudbeckia have relatively loose roots so dividing by hand or with a sharp knife is easier.

3.Next cut back this years growth to about 1 inch or 2cm. This means the plant focuses all its efforts on new roots and doesn’t, therefore, waste energy on foliage production or excess transpiration (the process that plants uptake and lose water with).

4.Ensure you have enough root to ensure a successful transplant. You may be surprised at how little you need to create a new plant. The smaller the division the longer the new plant will take to fully establish and get to its ultimate width and height. I tend to choose a root ball that sits neatly in my palm with most plants. This ensures a good healthy division for the plant’s regrowth. For most hardy Geraniums, you can be really thrifty with tiny parts of root but the plant will take longer to establish.

5.Replant your divisions quickly to ensure that they don’t lose too much water. You then need to thoroughly water them in. Even if the ground is wet. Label these new plants so next season you know exactly what they are, especially if you’re dividing a lot! If you can’t plant them on straight away or you’re sharing divided plants you can pot them into compost until they are ready to plant out.

When should I divide plants?

For most herbaceous perennials the best time to lift, divide and replant is early Autumn or Spring. You want to avoid frost at all costs and abstain from dividing plants when they are in flower. This is because frost makes establishing roots incredibly hard and can kill off new plants. Secondly moving plants when they are in flower is when they are at their weakest. They have expended all that energy on producing flowers, so won’t necessarily have the resources to them re-establish roots straight away.

Early Autumn or Spring is the best time for splitting plants

By moving plants when they are dormant you reduce the stress placed on them and have a far higher chance of succeeding with their relocation.

How often should I divide plants?

It’s advisable to divide herbaceous perennials every 3 or so years to encourage plant vigour. Of course, if the plant is healthy and flowering well you can leave it alone. Ornamental grasses often benefit from splitting every 3 years to stop the centre part of the plant becoming unproductive.

The main reason for dividing plants is to propagate them and create more copies of the parent plant. If this is the case you could do it every 2 years, giving a year for the parent plant to recover and bulk up again.

alt — All the above, *Geraniums*, *Sedum* and *Luzula* can be divided easily.

Summary

Dividing plants is a really economical and successful way to bulk up your gardens or share your herbaceous perennials with friends and family. The act of division encourages healthy plant regrowth and can often awaken an old tired herbaceous perennial, in particular grasses!

Although you may feel a bit apprehensive at first, fear not, plants are incredibly tough and this is a great way to get to know your most prized herbaceous perennials and become better gardeners!

If you’ve just divided some herbaceous perennials why not Tweet, Facebook or Instagram me with your pictures! You can also follow me on Youtube where I’ve got plenty of garden guide vlogs.