9 Perennials You Should Divide This Fall to Boost Blooms Next Year

Daylilies

Daylilies (Hemerocallis spp.) need dividing every four to five years to keep them at their peak of flower production. Overcrowded plants are subject to disease, and they tend to bloom less. Naturally robust, dividing daylilies takes a bit of elbow grease.

The first step is to cut the leaves back to about 3 to 4 inches. Then dig up the entire clump. There are a few ways to divide the clump. Plunging a pair of garden forks deep into the clump lets you pry the clump apart, though it takes some strength and may require two people. Repeat the process until you have several clumps that are manageable in size. Alternatively, turn the clump upside down and use a sharp spade to cut through the clump several times until you have 4 to 8 divisions.

Siberian Iris

Siberian iris (Iris sibirica) forms large clumps, but as they age, the center often stops blooming, and leaves and flowers develop around the edges of the clump instead. These gorgeous bloomers benefit from dividing every three to five years. 

Dig up the entire clump and remove dead or broken roots. Using a sharp spade or pruning saw, divide the clump into several sections, each with several fans of leaves and a good clump of healthy roots. Cut the leaves back to 5 or 6 inches and replant the divisions where you want them, being careful to spread the roots out evenly.

Hostas

Although hostas (Hosta spp.) often go for years without needing to be divided, they eventually outgrow their space and should be divided. Fall, after night temperatures have cooled but before the ground freezes, is the ideal time to tackle this job. In cooler climates, that usually means September, but gardeners in warmer climates can wait until October. 

Water your hosta before digging up the entire clump. If the clump is too large to be removed in one piece, use a sharp spade to cut through it and lift it in sections. Using a garden hose, remove as much of the soil surrounding the roots as you can. This will give you a better look at those roots so you can remove any that are damaged. You will also be able to see the “eyes” or buds at the crown of the plant.

Using a sharp knife or garden spade, cut through the clump and make sure to avoid damage to the eyes. Each new clump should have at least one eye, better two or three.

Barrenwort

Dividing barrenwort (Epimedium spp.) is much like dividing hostas. Both are clump-forming plants that increase their spread over the years. If you are using it as a groundcover beneath trees or shrubs, you may not need to divide it for several years. However, if it’s growing in a mixed bed of perennials, it may overtake its neighbors as its clump expands. Dividing it is the best way to keep it in bounds, and the best time to do it is in late summer or fall.

Dig around the entire clump and lift it out of the ground. Cut the clump into sections with a sharp saw or knife. Alternatively, use a sharp spade to cut out sections of the clump that are growing beyond the space you want it. Replant the sections 1 to 2 feet apart give your new plants room to spread.

Bleeding Heart

Bleeding hearts (Dicentra spp.) often grow many years without the need for dividing, although after about four or five years, you may notice a decrease in flower production. When that happens, you’ll know the time has come to rejuvenate your plant by dividing it into smaller sections. Wait until the foliage is dying back at the end of summer before dividing.

A clump of bleeding heart produces a wide-spreading but fairly shallow root system, so dig a wide circle around your plant to include as many roots as possible. Often, there are small eyes near the soil surface; avoid damaging them in the process. Lift the entire clump if possible, or use a sharp spade to lift sections. Remove damaged or hollow roots. 

Using a clean, sharp knife, cut the clump into sections, each containing 2 to 3 eyes. Replant sections immediately at least 18 inches apart from each other and other plants.

Hardy Geranium

This summer-blooming perennial can be divided in spring or fall, but since spring is so busy with many garden chores, why not do it this fall? Hardy geraniums (Geranium spp.) appreciate division every three to five years; otherwise, they tend to get leggy, and their center may die out.

Start by cutting back the top growth to just a couple of inches to expose the crown of the plant. Dig up the clump and lift it out of the soil. Often, it works to simply use your hands to pull the clump apart into smaller sections. Or use a sharp knife. Untangle the roots and spread them out in their planting holes. Space plants 1 to 3 feet apart.

Speedwell

Late summer or early fall is the ideal time to divide this spring and summer bloomer. Mat-forming types of speedwell (Veronica spp.) often tend to die out in their center; dividing them will rejuvenate them. Erect types also benefit from division every three to four years.

Dig up and lift the entire clump. Cut the foliage back to 3 or 4 inches. Discard the tired-looking center and separate clumps from the outer edges by hand or use a sharp knife or pruning saw. Be sure each clump includes abundant roots. Replant the sections 1 to 3 feet apart, depending on the variety.

Solomon's Seal

The arching stems of Solomon’s seal (Polygonatum spp.) create an elegant groundcover in shady gardens. This perennial spreads by underground stems called rhizomes, which make division of the plant easy. Dig up plants, or sections of plants, and use a sharp knife to cut the rhizome into sections, each with several growing points. Plant the sections immediately about 3 feet apart.

Shasta Daisy

Shasta daisies (Leucanthemum x superbum) spread wherever they're happy, but flowering may drop off after a few seasons. The solution is to rejuvenate your plants every two to three years by digging and dividing the clump. Fall is a great time to do so, and it's best done on a cool, overcast day.

Cut back the top growth to about 4 inches. Dig the entire clump and lift it out of the ground. Remove most of the soil around the roots so you can separate sections from the perimeter of the clump, by hand or with a knife. Each should contain a healthy bunch of roots. Discard the tired center portion of the clump. Replant the new divisions where you'd like them, spacing them 1 to 2 feet apart.