Plan a beautiful 2027 growing season by dividing perennials this fall

By late summer, your perennial beds have had an entire growing season to show you what’s working—and what may be getting a little crowded.

Maybe your daylilies have grown into an oversized clump. Perhaps a once-impressive perennial is producing fewer flowers than it used to. Or you may simply want to move some established plants to fill another area of your landscape.

For many Minnesota perennials, late summer and early fall can be a good time for division. But timing matters. Dividing the right plants at the right time gives them an opportunity to establish new roots before winter, while dividing the wrong plants can interrupt flowering or leave them poorly prepared for cold weather.

Here’s how to decide what you can divide now, what should wait and how to approach late-summer perennial division successfully.

Why divide perennials?

Perennials don’t necessarily need to stay exactly where—or exactly how large—they were originally planted.

As many varieties mature, their root systems and crowns expand. Eventually, plants can become crowded and compete for water, nutrients and growing space. Some perennials may begin producing fewer or smaller flowers, while others develop a thin or dead-looking area in the center of the plant.

Division can help rejuvenate those plants.

According to the University of Minnesota Extension, dividing perennials can stimulate new growth, reduce competition for nutrients and water, improve airflow and help manage plants that have become too large for their space.

There’s also a practical bonus: one established plant can become several. Healthy divisions can be replanted elsewhere in your landscape rather than purchasing additional plants.

When is the best time to divide perennials in Minnesota?

A useful rule of thumb is to divide a perennial when it is not actively flowering.

For Minnesota gardens, that generally means:

Divide spring- and summer-blooming perennials in late summer or fall

Once these plants have finished flowering, they can redirect energy toward establishing roots instead of supporting blooms.

Divide fall-blooming perennials in spring

Plants that are preparing to bloom in late summer and fall generally shouldn’t be disturbed right before or during their flowering period. Give them the growing season to flower, then plan to divide them the following spring.

The University of Minnesota Extension recommends giving fall-divided perennials approximately four to six weeks before the ground freezes so their roots have time to establish.

That makes timing especially important in Minnesota. “Fall” shouldn’t be interpreted as waiting until leaves are falling from the trees and frost is becoming a nightly possibility. For many projects, getting the work done in late August or early September gives plants a much better opportunity to settle in.

Which perennials can you divide in late summer?

The best candidates are generally established spring- and summer-flowering plants that have finished blooming.

Daylilies

Daylilies are one of the most recognizable candidates for division.

Over time, a small planting can develop into a substantial clump. If flowering has declined or the plants have simply outgrown their location, dividing them after flowering can rejuvenate the planting while providing additional plants for other areas.

Daylilies have fleshy roots and can often be separated into smaller sections once the entire clump has been lifted.

Hostas

Large, established hostas can also be divided, although spring is often an easier time to tackle the job because the foliage is smaller.

If you’re dividing hostas later in the season, work carefully to minimize unnecessary damage to the plant and make sure the new divisions receive adequate water while establishing.

This can be particularly useful when a mature shade garden has become overcrowded or when you want to repeat the same hosta variety elsewhere in the landscape.

Peonies

Peonies are a particularly good example of a perennial for which fall division can make sense. The University of Minnesota Extension identifies fleshy-rooted perennials such as peonies as plants that are best divided in fall.

However, peonies require a little more care than many other perennials.

Their thick roots can break during digging, and planting depth matters. If the new division is planted too deeply, flowering can be affected. Peonies can also take several years after division to become fully established and return to their previous level of flowering.

In other words, divide a peony because it needs to be moved, propagated or rejuvenated—not simply because you feel like every perennial needs dividing.

Siberian iris

Siberian iris is another fleshy-rooted perennial that the University of Minnesota Extension recommends dividing in fall.

If an established clump has become crowded or flowering has declined, division can create additional growing space and reinvigorate the planting.

As with other late-summer divisions, don’t wait too long. Newly planted sections still need time to establish roots before Minnesota’s winter conditions arrive.

Other spring- and early-summer bloomers

The same general principle can apply to other established herbaceous perennials that have already finished blooming.

The University of Minnesota Extension’s August gardening guidance recommends dividing overgrown herbaceous perennials that have already bloomed during the year while leaving fall bloomers until the following spring.

Before dividing an unfamiliar variety, however, check recommendations for that specific plant. Not every perennial responds equally well to division.

Which perennials should you NOT divide in late summer?

Just because a perennial can be divided doesn’t mean August or September is always the right time to do it.

Fall-blooming perennials

If a perennial is blooming now—or is covered in buds preparing to bloom—leave it alone.

Fall-blooming plants are generally better candidates for spring division. Disturbing the roots immediately before flowering adds unnecessary stress and can sacrifice one of the most valuable features of a late-season landscape: fall color.

Newly planted perennials

A plant that was installed this spring or summer usually doesn’t need to be divided. Give it time to establish a strong root system before considering division.

Stressed plants

Late summer in Minnesota can still bring hot, dry conditions. A perennial that is already struggling with drought, disease or another source of stress may not be a good candidate for immediate division.

Address the underlying problem first.

Perennials that dislike division

Some plants simply don’t respond well to being dug up and split.

The University of Minnesota Extension specifically points to false indigo (Baptisia) as a plant that should generally not be divided or moved because of its long, deep roots.

Knowing what you’re growing is important. Don’t assume that division is appropriate simply because a plant is classified as a perennial.

How do you know when a perennial needs dividing?

You don’t need to divide a healthy perennial simply because it has been in the ground for a certain number of years.

Instead, look at the plant.

Signs that division may be beneficial include:

• The plant has developed a bare or dead area in its center.
• Flowers have become smaller or less abundant.
• The plant is growing beyond its intended space.
• Nearby plants are becoming crowded.
• Stems increasingly require support.
• You want to propagate a healthy plant elsewhere in the landscape.

If the plant looks healthy, flowers well and fits comfortably in its space, there may be no reason to disturb it.

How to divide perennials successfully

Once you’ve identified a good candidate, preparation can make a significant difference.

1. Choose a cool or cloudy day

Avoid digging and dividing plants during the hottest part of a sunny August afternoon. Cooler, overcast conditions reduce moisture loss and transplant stress.

If the soil is dry, water the area the day before you plan to work.

2. Prepare the new planting location first

Know where the divisions are going before you dig up the original plant.

The less time exposed roots spend sitting above ground, the better. New locations should also provide the appropriate sunlight, drainage and growing space for the particular variety.

3. Dig up the entire clump

Use a spade or garden fork to dig around the plant and carefully lift the root mass.

Try to preserve as much healthy root material as possible.

4. Separate the plant into healthy sections

Depending on the root structure, divisions may pull apart by hand or require a sharp knife, spade or garden fork.

The University of Minnesota Extension recommends that each new division retain approximately three to five vigorous shoots along with a healthy root supply.

5. Replant promptly

Keep divisions shaded and moist while you work and get them back into the ground as quickly as practical.

In most cases, the division should be replanted at approximately the same depth at which the original plant was growing. Some species, including peonies, have more specific planting-depth requirements.

6. Water thoroughly—and keep watering

Planting isn’t the end of the job.

Late-summer divisions need consistent moisture as they develop roots. Minnesota can experience dry stretches during August and September, so don’t assume occasional rainfall will provide everything newly divided plants need.

Continue monitoring soil moisture into fall. University of Minnesota Extension guidance recommends keeping newly planted herbaceous perennials well-watered until the ground freezes.

Don’t wait too late in the Minnesota growing season

One of the biggest mistakes with fall perennial division is waiting until “fall” feels like fall.

A sunny September weekend may feel like plenty of time, but plants don’t establish themselves according to the calendar. They need suitable soil temperatures and enough time to produce roots before the ground freezes.

That’s why late August into early September can be such a useful window for Minnesota landscapes.

You can see which plants have become overgrown, most spring and summer bloomers have finished flowering, temperatures will soon begin moderating, and there’s still meaningful growing time ahead.

Late summer is also a good time to evaluate your entire landscape

Dividing perennials doesn’t have to be an isolated gardening chore. It can also be an opportunity to take a broader look at how your landscape performed this year.

Which plants became overcrowded? Which areas lacked color? Are some plants receiving too much shade as nearby trees mature? Did certain beds become difficult to maintain? Are there gaps where divisions from established plants could provide inexpensive new growth?

Taking note of those issues now can make next year’s landscape better.

Late summer is also an excellent time to identify larger improvements that may require professional planning, from redesigning perennial beds and improving drainage to renovating turf or updating aging landscape features.

Need help getting your Minnesota landscape ready for fall?

Healthy landscapes require different types of attention throughout the growing season, and late summer is an important transition point.

Whether you’re managing an established residential landscape or maintaining a larger commercial property, understanding which plants need attention now—and which tasks should wait—can help protect your investment and set the landscape up for a stronger spring.

Lakeshore Landscaping provides professional landscape maintenance and enhancement services for properties throughout Minnesota. Contact our team to discuss your landscape and the improvements that can help it look and perform its best.

Sources

University of Minnesota Extension. “How and when to divide perennials.” University of Minnesota Extension, reviewed 2026.

University of Minnesota Extension. “August garden checklist.” Yard and Garden News, August 2026.

University of Minnesota Extension. “Flowers.” Gardening in Minnesota, University of Minnesota Extension.