How And When To Divide Perennials

Plant dividing is a clever gardening technique that involves dividing a plant in half to create a new plant for free.

Most perennials benefit from division every two to three years to maintain their health and vigor and ensure they look and function at their best. Dividing a plant can also help prevent the plant from spreading too much.

From hostas to lavender, read on to learn everything you need to know about properly dividing plants—including the best time of year to do it.

When should you divide plants?

“Plants can be divided successfully at almost any time if they are then well watered,” he says RHS. “Division is most successful when the plants are not actively growing.”

Spring-flowering plants tolerate division at a different time of year better than, for example, summer-flowering plants.

“Spring flowering plants should be divided when they start to grow new roots, usually in the summer after they have finished flowering,” says Graham Smith MCIHort, gardening expert at LBS Horticulture.

“Summer bloomers, on the other hand, should be divided in spring or fall, but only when the soil is dry enough to work with. If the soil feels too wet, it is best to wait until spring, especially for tender plants.”

Whatever plant you decide to share, the most important thing is to water it well. And if the plots are replanted, it should be done as quickly as possible to prevent drying out.

“If you want to increase the number of your plants through division, the task can be carried out more regularly,” says the RHS.

Close-up of spring dividing the bush of a hosta plant and planting it in the ground, hands of a gardener in gloves with shovel working with hosta, flowerbed landscaping in the backyard

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When should hostas be divided?

“In general, hostas can grow into large, beautiful plants that don’t need to be divided at all. However, if you want to prevent overcrowding, make room for other plants, and preserve plants for free, sharing is a great way to achieve this,” says Morris Hankinson, director of Hopes Grove Nurseries.

“Hotas should ideally be divided in spring when they are producing new growth, or in late fall when growth begins to slow down,” adds Graham.

Small plants with fibrous roots like hostas can be lifted and carefully pulled apart. This should create small clumps for transplanting.

“After dividing, the mother plant and section should be replanted immediately or the sections should be potted at the original planting depth before digging up,” Graham continues. And when you grow hostas in pots, they fill up their space much more quickly, so you should divide them or transplant them into a larger pot about every three years to accommodate them.

Hosta plant with flowers growing in the garden

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When to divide rhubarb plants?

Rhubarb plants can also be divided. If your rhubarb leaves are overcrowded, that's a telltale sign that it's time to divide them.

As with any plant you choose to divide, you should only choose healthy plants to prevent the spread of viruses. Rotten or diseased plant parts should also be removed.

“Rhubarb plants should be divided between mid-autumn and early spring, ideally around November when the entire clump is dormant,” adds Graham.

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When should lavender plants be divided?

“Lavender plants can also be propagated by dividing their roots,” says Graham. “In early spring or fall, lift the plant’s root ball out of the ground with a spade and then divide it into two parts.

“Plots should be replanted at a sufficient distance from each other to give them room to grow, and not planted too densely.”

Dividing lavender is only possible if it is rooted in several places in the ground. “Since lavender is a woody plant, it is much better to propagate it through cuttings.”