Perennial plants (from flowers to fruits and vegetables) need to be divided every once in a while to help them stay healthy – about every two to five years. Planning ahead will help you stay on top of this monstrous chore so stay focused and know that it will bring you a healthier garden next year.
Fall Division Promotes Healthy Plants
Although you can divide and transplant perennials in spring, fall is the optimal time to perform this chore.
In the fall, plants (except annuals) naturally direct energy away from their above-ground parts to bolster their roots in preparation for winter dormancy. Because energy is being diverted to the roots, the roots of newly divided and transplanted perennials already have the urge to establish themselves. This urge to set down roots helps your plant get settled in its new home before winter sets in.
Spring division can be hard on plants since this is the time of year when they are diverting most of their energy away from root development and into above-ground growth. Because this is also the time when plants are sending up new shoots, digging and dividing in the spring can damage the fragile new growth. If you do wait to divide until springtime, be gentle with your plants.
It may be tempting to let your perennials grow as they will, and if you have unlimited space in your garden, that’s fine. However, to keep your garden beds tidy and healthy, you should divide your perennials every three to five years.
As many perennials grow, they spread out with the central portion of the plant being the oldest and the outer portions being the youngest. Just as with people, older plants don’t grow as vigorously as their youthful counterparts and succumb more easily to diseases and pests. Dividing the plant and removing the older portions keeps your plants thriving and healthy.
How to Divide
While you may be able to divide smaller plants with a trowel, dividing a deeply-rooted perennial requires a sturdy shovel and a strong back. This is especially true if you haven’t divided in a while or if you have heavy soil. Of course, you should always work wisely. If the clump of plant you dig out is too heavy to lift on your own, get someone to help.
The process of dividing requires you to get as much of the plant out of the ground as possible and then to split the older sections of the plant away from the newer sections.
1. Use a shovel to dig into the ground completely around the plant. Dig about 4 to 6 inches (10 to 15 cm) away from the plant’s base to ensure you get as much of the root ball as possible.
2. Using the shovel as a lever, lift the plant out of the ground. If the plant is very large, have a friend help you shift the plant.
3. Tap off some of the dirt from the root ball so you can see the roots.
4. Divide the plant. Some plants have new sections that can be easily teased apart by hand. Other plants have tangled or fleshy root masses that will need to be cut using a shovel or pruning shears. Make sure your equipment is clean and make the cut as smooth as possible.
5. Discard and trim away any portions of the plant that aren’t doing well. For example, poor growth, dead patches, or rot.
6. Plant the divisions. You’ll want to use a few of the divisions to replant the area you just dug up. The remaining divisions can be planted in other areas of the yard or potted up and given to friends and neighbors.
Note: If you cut into a fleshy root mass (such as those found on bulbs), allow the cuts to air dry for 24 hours before proceeding. Do not leave the divisions where they will get wet. This allows the wounds to scab over which helps protect the fleshy cuts from disease and pests.
Dividing may seem like a daunting a chore, but it’s one you don’t have to do very often and one that keeps your plants healthy and your garden thriving.