HomeDIYHow to Divide Perennials, and Illustrated Guide
How to Divide Perennials, and Illustrated Guide
May 1, 2019
Hello! Got questions as to how and when to divide perennials? You’ve come to the right place. I just finished dividing some perennials and thought I would share the steps you need to know to divide perennial flowers successfully! In this example I will be dividing a New England Aster perennial, similar to the one pictured below. See what perennials can be divided, when they should be divided, how they should be divided, and what you shouldn’t divide.
What time of year should you divide perennials?
There are generally two safe times for dividing perennial flowers. In early Spring when new foliage and shoots emerge, and in early Fall. The main concern when dividing perennials is that if the flower is blooming, or about to bloom then it won’t devote as much energy to root growth. Also, since most flowers bloom when it is hot out the lack of roots can be a real concern for watering.
Dividing perennials in early Spring has several benefits.
The plant will have plenty of time to establish new roots before it blooms.
It will have ample time to make roots before winter.
The outside temperatures will be cool, so the water demands on the plant will be low
Dividing perennials in early Fall is more tricky, as you need to do this after the plant has bloomed, but before cold weather really sets in. This is necessary so that the plant has time to establish roots before the ground freezes. If daytime temperatures are around 50F-60F (10C-15C), then it is a good time to divide.
When and Why should you divide perennials?
A great tip on when you should divide your perennials is if it looks good, full, and healthy. What I mean is, if a plant has stems/blooms coming from all areas of the plant, I will consider dividing it at the end of that year, or early the next Spring.
Many perennials will grow quite large after several years. If they are not divided, the center sections will no longer have enough soil for their roots and may stop producing flowers. This can result in a flower ‘ring’ with a dead center.
Another benefit of dividing perennials is that you are basically getting ‘free’ plants! So, if you spent $20 on a large perennial from a nursery one year, perhaps it will be large enough the following year to divide into 3-5 plants! You could expand your garden and save $50-$100 in the process by dividing!
What perennials can be divided?
The following perennials are great for dividing and transplanting. These are prety much all perennials with fiborous roots that have multiple corms or sections that produce their own stems. Aka these are plants that make their own little islands of foliage, or colonies.
Basically any perennial that has a taproot should not be divided. It is very difficult, as all blooms and stems come from a single root crown. Although it is possible to divide these, but slicing down the length of the taproot, the plant may not survive. Splitting or cutting this root usually causes too much damage that the ‘divisions’ will not make it. So, if you are unsure, research what kind of root your flower has, and if it has a taproot, then you probably shouldn’t divide it. Perhaps your best option for free plants for taproot perennials is to save some seeds and germinate new plants!
An illustrated guide to dividing perennials in 5 Easy Steps
Follow these 5 easy steps to divide your perennials. I’m going to show you pictures of a New England Aster as an example. I shared these clumps with a neighbor who wanted to establish a wildflower garden.
Assemble your tools. You will need the following to divide your perennial flowers. Also make sure your plant has moist soil. Water it the day before if you are unsure, as it will make removal easier.
Spade or pitchfork
Garden knife, trowel, or hatchet. Even a pruning saw can work.
5 gallon bucket or several pots. Even laying the plant on a tarp or sheet of cardboard works.
Dig up your plant. Use a spade or pitchfork to loosen the soil around the plant, and remove it from the hole. Make sure you get under the roots and can pull up the entire ball. If the plant is large, then dig the plant out in a circle several inches past its drip line (where the leaves extend to, straight down to the dirt).
Remove the soil from the roots. Use a hose or bucket of water to help remove soil. You will then be able to see what parts you can divide. Or, if a solid crown, you can just slice it up (depending on species).
Separate the plant. Use your knife, trowel, spade to cut off sections of the plant. Some plants can even be separated by hand like Columbine (only in the fall) or Yarrow. Each section needs to have at least a nice chunk of root crown to be viable, with some shoots attached to it. In my example, I was just turning one plant into three, so I just sliced through and cut the entire plant into thirds.
Replant the sections to the same depth as you dug them up. Do this immediately and water. If you can’t replant them right away, put them in flower pots with soil and water. Monitor the plant for a couple weeks to make sure it has enough moisture.
Caring for your divided perennials
You should pay close attention to the perennials after dividing and planting them. Make sure they don’t dry out. Periodically check the soil with your finger to make sure it is damp. If the soil feels dry, water it thoroughly. Adding mulch around your perennial can also help retain moisture.
Depending on how large your divisions of the perennials were will dictate how much they bloom during their next growing season. The large Aster I divided should bloom thoroughly, as each section was quite large. If you divide the perennial to small sections, the same as a 1st year seedling, then you may not have any blooms until the following year. This is because the plant will need to reestablish itself.