Dividing perennials keeps plant growth under control, rejuvenates cramped roots, and is an easy way to spread plants around the garden. It’s a skill that every gardener should know how to do. We’ve divided the process into simple steps below!
Signs a Perennial Needs To Be Divided
If your iris is running out of room, or your daylilies are starting to crowd out their neighbors, it’s time to divide them. Bald spots in the center of your catmint are another sign to take out the spade. The same signs apply to most perennials: not enough room to grow, tightly packed roots, or dying foliage in the center. It’s always best to divide proactively before the plant starts to suffer. This frees up space for it to grow, while giving you other plants to share with friends or transplant elsewhere in the garden.
The Best Times of Year for Dividing
It’s best to divide plants when they are not in bloom, so they can focus their energy on regrowing roots and leaves after being transplanted. Early spring is the ideal time to split up the fall-bloomers. If you uproot them after the leaves emerge, they will still have lots of energy to grow into the new location. Late or mid-September is a great time to divide spring-bloomers. Five to six weeks before the ground freezes gives them ample time to establish before winter.
How To Divide Perennials
- Choose an overcast day, or work in the morning or evening to reduce desiccation from the sun.
- Dig up the parent plant, ensuring you dig wide and deep enough to bring up most of the roots. The plant’s drip line usually tells you where the roots begin.
- After you dig out the plant, remove any loose soil around the roots. Then separate the plant into smaller divisions by gently teasing apart the roots, prying them apart with a fork, or cutting them with a spade or knife.
- Replant smaller divisions in the same hole and transplant other divisions elsewhere in the garden.
Tips For Successful Replanting
Replant only the healthiest pieces and discard any portions of the plant that look weak or buggy.
Water your perennials the day before you dig. Keep the exposed roots in the shade while you’re working and water the plants well after transplanting. If you have to keep them above ground for any length of time, soak the roots in water.
Rejuvenate the soil with organic matter like compost, aged manure, or organic fertilizer when you replant the divisions.
Leave space around your divisions to ensure that they have lots of room to regrow and replant them at the same level that they were in the ground before.
How To Separate Roots Appropriately
Some plants, like yarrow and coral bells, have thin, fibrous roots that you can pull apart with your hands. Others, like bee balm and black-eyed Susans, form a clump of sod at the surface that can be sliced with a spade. Tubers and rhizomes, like what you’d find on an iris, can be cut with a knife, as can a taproot. Remember to keep at least three growing points for foliage per root. Finally, some flowers, like astilbes and Soloman’s seal, have a woody root at the surface, which can be sawed apart.
Take advantage of the fall to divide some perennials before they begin to get crowded. You’ll not only give them space to grow, but suddenly have extra plants to spread throughout your landscape. Feel free to stop by our garden center in the Quad Cities for more advice, tools, soil amendments, or anything else that you need for success!