Divide These 8 Perennials in October – It's the Easiest Way to Make More of Your Favorite Plants for Free

Every method of plant propagation has its bit of magic. It’s amazing to see a little green shoot emerging from a tiny seed or to watch roots appearing on the lower end of cuttings. But division has a huge advantage that seeds and cuttings lack: you start with one perennial, then, presto chango, you have two, or three, or four.

Dividing plants is a simple, highly effective method used to propagate perennials. It doesn’t require any technical or botanical knowledge. All you need to do is lift a mature perennial from the ground, then divide its root system into two or more distinct sections to be replanted.

But timing is important when it comes to division. Never try this in the heat of the summer, nor in the heart of the winter. Along with early spring, October is one of the very best times to propagate your perennials by division, as the soil is still workable. You want to dig the plant up, divide it into several rooted sections, and get the roots of the sections established before the first frost.

How to Divide Plants Successfully in October

It’s a good idea to get an overview of the division process before trying it on a perennial. The first rule to remember is that you can’t divide annual plants – only perennial plants have the established root structure that allows for this type of propagation.

Use a sharp spade or garden fork to dig a circle around the perennial before prying out the rootball. Then you might use two garden forks to divide the roots, although I personally find it easier to do by hand. Finally, do the actual division with something sharp, like a garden knife, a pruning saw, or a spade. Alternatively, a Root Slayer Perennial Garden Shovel, available on Amazon, is a multipurpose tool that lets you cut neatly around the plant, ease it out, and slice it into divisions.

Can you pause once the plant is out and divided? Nope, no rest for you at this stage. Immediately replant each division, and do so at exactly the same depth at which it was previously growing. Use your fingers to press down the soil and eliminate air pockets, then water thoroughly. If you're potting up divisions before planting them elsewhere, use a high-quality potting mix, such as Miracle-Gro Potting Mix from Walmart, to help the roots establish quickly before winter.

The newly created divisions will need adequate water until they establish. Water the soil around the plant several days before dividing, then deep water the sections immediately after they are in the ground. Keep the soil consistently moist for several weeks to allow the roots to re-establish.

Now, let's dive into the best plants to divide in October.

1. Hostas

Hostas are shade garden favorites, but they can grow larger than you might expect. One great way to control plant size is division. Not only can you cut back the size of the clumps, but you get new ones as well.

If you decide to divide hostas in the fall, do it in October. Using a sharp spade or shovel, dig out the entire plant and place it carefully on the ground. Separate tuber clumps.

2. Sedum

Sedums, also known as stonecrops, are clump-forming succulents that are easy to divide. You can divide sedum plants in autumn, right after they finish blooming. Use a garden spade or fork to dig out the plant with its entire root mass, then clip back the tallest stems to several inches. This makes them easier to handle. Chop the clump into smaller sections, each one with healthy green stems on top and a root cluster on the bottom. Plant each division in a sunny location at the same depth it was growing previously. Firm the soil and water thoroughly.

3. Peonies

If your peonies are overgrown, divide them in the fall. They are somewhat picky about division, so be sure to walk through all the steps.

First, cut back your peony stems, then dig out the plant, including the thick roots. Set the plant on the ground, then hose down the root ball. This is important because you need to see the peony's “eyes”, which look like pink buds at the crown, and make sure each division has at least three eyes and strong roots. Replant the divisions immediately, placing the eyes no more than 2 inches (5 cm) below the surface of the soil.

4. Bearded Iris

Bearded irises are among the easiest perennials to divide. All you need to do is dig up the clump, prune down the foliage to about 6 inches (15 cm) long, then chop up the clump into smaller divisions. Afterward, let the plant dry for a full day, then replant the divisions. The top of the rhizomes should end up just at the level of the soil surface.

5. Astilbes

Divide established astilbe plants every few years. Just dig them up, trim back the foliage, and divide them with a sharp shovel or spade. If the plant is too big to dig up, just cut out sections from the standing plant. Replant astilbe segments in a new site, watering generously.

6. Bee Balm

Divide bee balm in fall after flowering ceases but before the first frost. Use a spade to dig around the clump, leaving plenty of room to make sure you don’t dig through the root system. Dig up the clump, lift it up, and shake out extra soil. Toss the center of the clump – it will be woody, hollow, or dead, and it won’t flower well again. Divide the plant with hand pruners, making sure each section has three shoots or growing buds. Replant bee balm plants at the exact same depth as they were planted before, tamping down the soil. Water well.

7. Bleeding Heart

Divide bleeding heart plants in October, after the plant’s foliage has naturally died back. Dig out the root clump, then use a sharp knife to divide it into sections, each one with at least one growth bud. Replant immediately and water well.

8. Phlox

Divide phlox at least four weeks before the first hard frost. October is generally a perfect time to do the deed. First, cut back the foliage. Then, use a sharp spade to dig up the entire phlox plant and chop the root clump into sections. Each section should have at least three shoots and some sturdy roots. Replant immediately and water generously.

How to Care for New Divisions Before Winter

The watering you give your divisions after replanting is very important. Be sure to water each one well, then water regularly to keep the soil moist.

Mulch the area around each division to help protect the new plants from winter chills. Apply a 2–3 inch (5–8 cm) layer of organic mulch, such as straw or pine bark, like these Timberline pine bark nuggets from Walmart, to insulate the soil and protect the roots from temperature fluctuations. Keep the mulch clear of the plant's crown to prevent rot.

Plant Dividing Essentials