Is one of your garden plants getting a little too comfortable? If it’s crowding its neighbours or spilling into the path, you may be able to divide it.
Dividing a perennial means turning one established plant into two or more smaller plants. It can give an overgrown plant more room, fill an empty spot in your garden, and leave you with an extra plant to share.
Fall is a good time to divide some perennials. The trick is knowing which ones are ready—and giving them enough time to settle in before winter.
First, what’s a perennial?
A perennial is a plant that lives for more than two growing seasons. Many die back above ground in winter, then grow again from their roots in spring.
Some perennials grow into bigger and bigger clumps. When a clump gets crowded, you can sometimes dig it up, separate it into sections, and replant each section. Every new piece needs healthy roots and stems or buds so it can grow on its own.
How do I know if my plant needs dividing?
Look for these clues:
- It’s too big for its space. It’s covering a pathway or crowding other plants.
- The middle looks bare. There’s healthy growth around the edges, but little in the centre.
- It’s producing fewer flowers than it used to. Crowding can sometimes be part of the reason.
- You want more of it. A healthy, established plant may give you enough to fill another spot.
If your plant looks happy and has plenty of room, you can leave it alone.
Is fall the right time?
Fall can work well for many hardy perennials that have finished flowering, especially spring and early-summer bloomers. Cooler weather makes the job easier on the plant than dividing during summer heat.
Timing matters more than the date on the calendar. Aim to divide at least four to six weeks before the ground freezes. That gives the new pieces time to start growing roots in their new spots. If winter is coming quickly where you live, wait until spring instead.
Hostas, daylilies, and some other clump-forming perennials may be candidates for fall division. But there’s no one rule that fits every plant. Irises, peonies, and ornamental grasses, for example, can need different timing or a slightly different method. Check the care advice for your specific plant before you start.
A good beginner rule: If you don’t know what the plant is, identify it before digging it up.
What do I need?
- A shovel or garden fork
- A clean, sharp knife or spade if the roots are tough to separate
- Water
- A place to put the new plants
It helps to choose the new planting spots before you dig. Roots are happier back in the ground than sitting beside your shovel while you decide where everything should go.
How to divide a perennial in six steps
1. Water it
If the soil is dry, water the plant the day before. Moist soil is easier to dig, and the plant will be well hydrated when you start.
2. Dig around it
Push your shovel into the soil a little way out from the stems. Work your way around the plant, loosening the soil and trying to keep a good portion of the roots attached.
3. Lift the plant
Gently lift the whole clump out of the ground. Bigger plants may take a bit of muscle. Don’t panic if a few roots break.
4. Separate it into sections
Look for natural groups of stems or buds with roots underneath them. You may be able to pull these apart with your hands. If the clump is tightly packed, use a clean knife or sharp spade.
Make two or three sturdy sections rather than lots of tiny pieces. Each section needs healthy roots and some stems or buds to grow from.
5. Replant right away
Put each section into its new spot at the appropriate depth for that plant—usually about as deep as it was growing before. Fill the hole with soil and gently press it around the roots.
Give the new plants room to reach their full size. A small division can grow into another large clump over time.
6. Water thoroughly
Give every section a good drink after planting. Check the soil over the following weeks and water when needed while the roots settle in. Fall rain can help, but it’s still worth checking rather than assuming the plants have had enough.
Can I divide my hydrangea, too?
A big hydrangea might look like a giant perennial, but don’t split a mature hydrangea down the middle. Hydrangeas are woody shrubs, and dividing their root ball can seriously damage them.
If your hydrangea has outgrown its space, look into the right pruning or transplanting approach for that variety. Making new hydrangeas from cuttings or layering is a different project.
One plant, more possibilities
That’s really all there is to the idea: choose a perennial that benefits from dividing, pick the right time, keep healthy roots and growing points on each piece, and water the pieces after replanting.
If you’re unsure about the plant or fall arrives early in your area, it’s fine to wait and check its care information first. Your garden is allowed to be a learning experience. In fact, that’s most of the fun.
