by Barb Levisay
This past weekend, we held our first gardening workshop of the season, Spring Flower Gardening: Dividing and Moving Perennials. We had a great turnout but it was too cold to work outside so we made a big mess in the greenhouse cutting up fern root balls and pulling apart black-eyed susan roots. Now that it’s finally getting warm, you can get to work outside to divide your perennials and help them thrive.
Spring is the best time to move ferns and grasses
After three to five years in the ground, most grasses and ferns start to outgrow their original space and will benefit from division. When you see sprouts coming up in the ornamental grasses and fiddleheads poking up from the ferns, it’s time to dig and divide. Both grasses and ferns require some tough love when it’s time to divide them.
The first challenge comes in digging out the plants. Grasses can establish deep, dense root balls that require a sharp spade and lots of muscle. Ferns generally have a shallow root system, but the roots become tightly intertwined, forming a dense mat. Use your sharp spade to trim around the edges and lift up the whole structure if you can, but you may need to slice the mat into manageable pieces to get them out.
Fiddle heads of a maidenhair fern poke up in the spring warmth.
To divide the root balls of both ferns and grasses, I use an old bread knife. The serrated edge cuts cleanly through the dense root ball or mat. While it seems harsh, it’s really better for the health of the plant than hacking at the roots with a shovel or trowel. With the bread knife, cut the grass root ball or fern mat into several pieces. Place each piece in a hole at least twice it’s width and fill back in with soil. You’ll want the crown of the root ball to be about level with the surrounding soil. It’s very important to give them a good soaking so that they get well settled into the soil.
Tips for dividing flowering perennials
Most of your summer and fall blooming flowers are happy to be divided in the spring. It’s a great time to reposition those plants that weren’t in quite the right spot. When you’re ready to dig in, keep these things in mind for the best results.
Inspect the plant to see how far the roots extend before you dig so you can include as many as possible. Better to start digging further out and peel off the dirt from the roots.
When you’ve dug up the root ball, examine it to see how best to approach separating the plants. For some plants, you’ll be able to separate them with your hands. Mums, coreopsis and salvias are usually easy to just pull apart—and you can often get a lot of plants from one clump. Others, like echinacea and hostas are more difficult. Use a sharp spade or your trusty bread knife to separate the plant into smaller pieces.
As you carefully pull or cut the plant roots apart, focus on separating portions of the plants that have substantial roots. It’s best to get divisions in the ground right away, but if you can’t, keep them moist by wrapping them in wet newspaper or coving them with damp soil.
Dig a hole at least as wide as your root mass and spread out the roots as much as possible. Cover with soil so that the crown of the plant (or where the old stems come out) is level with the soil.
Most importantly, water them in well. By drenching the entire area, you help the feeding roots make firm contact with the soil and get right to work sustaining the plant. You also help to eliminate air pockets around the roots which can really set the plant back. Keep the plant well-watered until it is established and sending out new growth.
If you have deer around, protect your plants from getting pulled up. Deer will check out newly planted “deer-resistant” perennials by pulling them out by the roots. They may just spit it out, but unfortunately they don’t re-plant it. A temporary fence or cage can give the plants a chance to set roots and help them “hang on” when deer come through.
Phlox and daylilies will come back quickly after being divided to bloom in the summer.
Rule of thumb for perennial growth
So what can you expect from those plants that you divide? There is a handy rule of thumb that helps. “Sleep, creep and leap.” Most perennials follow the growth pattern:
First year the plant will sleep, focusing growth on roots instead of the leaves and flowers.
Second year the plant creeps, making some progress but not reaching full size.
Third year the plant will leap into its full potential and deliver on the promises of the label.
Dividing plants is one of the most rewarding tasks in the flower garden. You help the plant, you get more plants for free, and you can share your favorite plants with friends. Wins all around.
Next gardening workshop April 15th
We’ve got lots more gardening workshops planned for this spring and summer. Join us on April 15th at 10 AM for Best Practices for Vegetable and Flower Gardens. Gardening techniques have evolved over the past twenty years to work more closely with nature. For the vegetable garden, we’ll talk about no-till beds, natural pest control, crop rotation, and more. In the flower garden we’ll talk about the growing interest in native plants, pollinator gardens, ground covers, and overwintering habitats. Our workshops are fun and casual with plenty of time for questions.
If you have a gardening question, send a note to me at barb.levisay@gmail.com .