Perennials
Ellen Z
Fall is the perfect time to take a walk through your garden and take stock of what you’ve got. If your garden is thriving, your perennials get bigger every year. Eventually, they may become crowded and will benefit from transplanting and division.
Some perennials actually require division every few years to maintain vigor. Yarrow, hostas, daylilies, hardy geraniums, and some ornamental grasses may become thin at the center of the clump, producing fewer, smaller flowers and generally looking weak. Division will rejuvenate the plant.
When is the best time to divide perennials? The timing depends on when the plant blooms. Spring flowering plants should be divided in fall and summer/fall flowering plants may be divided either in spring or after they finish blooming in the fall. Dividing just before bloom time may prevent plants from flowering that year.
An additional benefit of transplanting in fall is that when plants come up the following spring, they resume their rounded, natural shape. A perennial that’s been cut in half in spring will keep its oddly semi-circular shape all season long.
Take a few moments to prepare. Water the plant that’s going to be divided a day in advance. This makes the soil easier to work. Think about where the divided perennials are going to go and have the holes or pots ready for them. The less time these plants spend with their roots exposed to the drying air, the less trauma they’ll experience. Also, don’t work at the hottest time of day, with the sun directly overhead. Heat dries out the plant and increases stress.
Perennials that produce crowns or spread by underground stems are easy to divide. Some, like bee balm (Monarda didyma, zone 3) or barrenwort (Epimedium species, zone 5), can almost be divided with your bare hands. You’ll need a shovel to dig up the plant, but you can tug apart individual pieces with your hands.
Hostas have fleshy roots that form a solid clump. To make dividing a muscular root system easier, you’ll need a few tools: a spade, and two garden forks.
Use a long, narrow spade to dig a perimeter three to four inches beyond the base of the plant to be divided. Dig down and toward the center of the plant, gradually cutting in beneath it to remove the root ball. You may need to pry with the shovel, using a gentle rocking motion. You may need to get down on your hands and knees to cut a few stubborn roots and release the root ball.
Remove the plant from the soil and place it on its side. Examine it at soil level. How many individual crowns does it have? How many smaller plants would you like to create? How large would you like those plants to be?
When you’ve figured this out, choose the spot for your first cut between two crowns. With the plant on its side, place the tines of one garden fork on the root ball at the point where you’d like to divide. With a firm push, stab the tines through the roots and soil.
Next, take the second garden fork and line up its tines along the same line, in between the tines of the first fork, facing the opposite direction. Push the second fork into the root ball with a similar, strong, swift motion.
Facing the line of demarcation, with one hand on each garden fork, gently push them away from each other, outward toward the edges of the plant. The root ball should pull apart easily along the line established by the two forks. You may need to rock the forks back and forth a little, or do some final detangling by hand. Repeat this sequence as many times as you must to get the number and size of divisions you desire.
Take the pieces of the perennial and replant them as soon as possible. Be sure to replant at the original depth, leaving the plant enough room to grow for another three years. Firm the soil around the roots and water well.
The new transplants may need extra TLC for a few weeks while their roots get established. A good general rule is to allow plants six weeks of non-stressful recuperation time after division and transplant. The plant should have six weeks of moderate temperatures to settle in, to recover from surgery; in Pike County, this means try to have your dividing done before the end of October.
Iris are an Exception
Everyone should grow bearded Iris. They’re low maintenance, drought tolerant, deer resistant, have gorgeous flowers in a huge range of colors, and foliage that’s attractive enough to grow for its own sake. Iris spread via rhizomes along the top of the soil, sending out roots from the bottom and leaves from the top. These should be divided immediately after flowering stops, which is usually in late July or August. Dig up the rhizomes and squeeze them. If any pieces feel mushy, get rid of them. Use pruners to cut the rhizomes at the obvious joints and replant, leaving the tops visible at soil level, and water well. To reduce stress, cut back the foliage to about six inches. New growth should resume within four to six weeks, and you’ll have flowers again next year.
Multiply by Dividing
Ellen Zachos
© Copyright 2010 Connections Magazine
