What Time(s) of Year Can You Divide Perennials?

You’ve probably heard that perennials can (and most should) be divided. Dividing perennials does two things:

• Dividing perennials keeps them from becoming root-bound and gives them more room to grow without chocking themselves out
• Dividing perennials gives you more plants! For free!

To be sure, dividing is a win-win all around. You get stronger, larger, long-lived plants and more of them to either expand your plantings or share with friends.

Jump to:

• When to Divide Perennials
• Dividing Perennials in the Spring
• Here are some of the advantages of dividing perennials in the spring:
• Dividing Perennials in the Fall
• Here are some of the advantages of dividing plants in the fall:
• Dividing Perennials at Other Times of the Year
• Here are some of the advantages of dividing perennials at other times of the year:
• The Key to Perennial Success No Matter What Time of Year you Divide Them
• The Time You Have is the Best Time to Divide Perennials

When to Divide Perennials

This brings up the question of when to divide your perennials. Some sources say spring. Some say fall. Some say it doesn’t matter.

So, what’s the truth?

The short version is that you can divide perennials at most any time of year when the ground is workable enough for you to dig in it. Some plants may have a preference for one or the other, but for the most part, the key is to get them divided when it’s time to do so so that they can continue to grow and thrive.

For most perennials, this is on a three-to-five-year cycle. Any time you notice your perennials are growing smaller or looking weak or less robust, or they stop producing or flowering as much, it’s a signal that they need to be divided.

Let’s look at some of the pros and cons of different times of the year when you might divide your perennials.

(*Tip: Remember that edible perennials like rhubarb and asparagus need dividing every few years, too.)

Dividing Perennials in the Spring

Early spring is probably the best time of year to divide perennials if you are choosing a certain time. This is because the plants are ready to start growing new roots and (later) new stems and foliage and because there is plenty of moisture around, left from the winter’s thaw and from spring rains (at least, historically speaking).

Spring is also a time when we are motivated as gardeners and have clearer visions of the changes and goals we want to make in our gardens and perennial beds.

If you’re dividing in the spring, try to do it earlier rather than later. The cooler days of early to mid-spring will be easier for divided plants to take and recover from. This time of the plant year also aligns with root growth over foliage and flower or seed production – essential to recovery and survival.

Here are some of the advantages of dividing perennials in the spring:

• Spring is generally a wetter season
• More ground moisture left from winter thaws
• More natural water (rain) helps keep divided and recovering plants evenly moist with less watering work from you
• Moister ground is easier to dig in
• Plants are small with little (maybe no) new plant growth, so there’s less to work around and less to damage
• Sets the new plant before its growth gets going so it is more likely to look nice and grow on time without looking poorly in the perennial garden
• If done early enough, plants still have a chance of flowering or producing this season (if they are flowering plants)
• As a gardener, you’re probably more motivated and looking forward to planting tasks and aren’t exhausted from the work of the long growing season
• Friends, neighbors, and others are often looking for new plants in the spring, which opens up opportunities to unload, share, swap, or sell divisions that you don’t need

Dividing Perennials in the Fall

Fall is the second-best time to divide perennials (although it is almost as good a time as spring, so it’s negligible at that).

As the garden season winds down, you’ll have a clear view of your plant’s performance, and it might be easier to see what needs dividing. You might also find that the slowing fall garden season leaves you with more time to be able to deal with the task of dividing.

If you are going to divide your plants in the fall, it is best to do it on the earlier side, when you have 6 to 8 weeks left before a hard freeze and before plants go dormant.

That said, if the ground is still workable, you can even divide after dormancy starts to set in or plants die back (though sometimes this makes it harder to find them). Just take a little extra care to fill in the soil and give them some mulch to protect the roots as the cold comes on.

Here are some of the advantages of dividing plants in the fall:

• Cooler weather is less stressful for plants
• Plants are starting to get ready for dormancy
• Most plants are done flowering by the fall
• Plants will be in place and ready to grow first thing in the spring
• Temperatures are falling instead of rising, and the sun is getting less strong, which means less heat stress on plants and divisions
• Lessening heat and sun strength results in less soil dehydration
• Fall is often moister and with more rain than late spring and summer
• Cooler temperatures may be easier to work and garden in (for you)
• Garden chores are lessening, and there isn’t the pressure or list of planting and other spring garden tasks to compete with
• Plants can be divided while there is still time for roots to establish before dormancy
• Since your perennial beds are starting to die back anyway, you won’t be as concerned with leaf and foliage damage or cutting plants back to divide them and have them look less good

Dividing Perennials at Other Times of the Year

If you live in a moderate to mild climate, you will be able to divide plants in the winter, too (as long as the ground isn’t frozen). Winter isn’t ideal for more northerly locations, but it can often be successfully done.

If you live somewhere where it is reasonable to divide perennials in the winter, this can be a cooler, easier time of year for you to work, without the pressures of other planting and garden maintenance.

The other time of year that you might want to divide your plants (probably the third most popular time behind fall and spring) is the summer. This is fine, but be aware that this is the time of year when divided plants and their divisions will need extra care to keep them from drying out.

It is recommended that you wait to divide your perennials until after they have stopped flowering, so you can enjoy the show and the plant isn't struggling to support blossoms. This is one reason to wait until a different time of year to divide your perennials.

Here are some of the advantages of dividing perennials at other times of the year:

• Dividing in summer or winter is mostly a matter of convenience and timing
• Simply put, it’s the time of year you divide because it’s probably when you find the time – and that’s fine!
• Summer is a season of growth, so plants will keep growing and getting established with good care
• You can work around plant flowering times and wait until after they're done blossoming
• Winter dividing means little care or maintenance, especially if plants go dormant, are kept moist, and are protected. They’ll sit until the spring growing season.
• Dividing in the summer gives you a chance to see how plants are performing and where you might want to move plants or make garden design changes
• Winter-divided plants don’t need frequent watering because they are dormant (but the ground should not be allowed to dry out completely, and it should not be dusty-dry)

The Key to Perennial Success No Matter What Time of Year you Divide Them

No matter what time of year you decide to divide your perennials, there is one key to success:

Water, water, water!

Perennials are tough and want to be divided, but the process is tough on roots. Especially for the divisions that are moved, there is uprooting and breakage that they have to heal from. And the plant may have foliage and growth it needs to support.

The most important thing to do is to make sure the roots can still get water so they don’t dry out and so they can support the plant until it builds its system back. This is simple. Just keep the plants watered!

• Keep the divided plant (the original plant that you split off from) and the newly-made divisions well-watered until they rebound and reestablish root growth.
• If in doubt, err on the side of over-watering. The normal rules don't apply.
• Keep the ground moist around divided plants.
• Check every one to two days and water when the top of the soil looks dry (or sooner if you’re just not sure).
• The goal is to keep the area of the root ball (whatever depth that is for the plants you divided) moist and with easy, ready access to water.
• Note the soil should be moist and well-draining, not soggy or muddy.

The Time You Have is the Best Time to Divide Perennials

Don’t shy away from a garden revamp because someone says it’s the “wrong” time of year to divide your perennials. Sure, early spring and fall may be the better times to do it, but if that’s not in the cards for you, it’s okay to revise your gardens and divide your perennials throughout the year when you have the time.

Garden consultant and designer Jess Zander (of Instagram fame You Can Do It Gardening) says that people overthink this, and there is no rule for dividing that is set in stone. She agrees that perennials can basically be divided any time the ground can be dug.

She also agrees that the only important thing is that you are dividing at a time of year when you are available to water the divided plants and their offspring that were moved until they are established afterward. For example, don’t divide just before you take off on a summer vacation for a week or two. Do it after you come back or two to four weeks before you go.

In the long run, when plants need to be divided, you’re better off dividing them so they can grow and thrive again rather than letting them become too rootbound, starved for nutrients, and starting to choke themselves off.

Here, it’s fine to bend or even break the “rules” for the sake of getting the gardening job done. The rules are really more of a guideline, anyway!