“United we stand, divided we fall”, “A house divided against itself cannot stand”. Notable quotes suggesting the consequences of being divided. But in a garden, division isn’t always a bad thing.
Recently in this column we have talked about the importance of fall planting, especially in a climate such as ours. Just like new plantings, this is the time of year to perform one of the most neglected garden tasks. Dividing clumping plants is an important chore that, once learned, is relatively easy to perform. The most common candidate in our coastal gardens for this task include daylilies, agapanthus, Shasta daisies, society garlic, fortnight lily, New Zealand flax, bird of paradise and most ornamental grasses. These plants comprise some of the most popular plants currently used in Orange County gardens.
After dividing an overgrown plant, you not only get new plants to fill the gaps in a bed or to plant in an enteriely new part of the garden, but you will improve the health of your plants so they will grow vigorously and bloom more profusely.
As a clumping plant grows, its new growth is on the outer edge of the clump. Many clumping plants eventually turn woody or die in the center as they push out new growth on their perimeter. The other reason to periodically divide these plants, especially in small urban gardens like ours, is to reduce the size of the clump. That bird of paradise, New Zealand flax or agapanthus that was so cute three of four years ago may now be a beast, outgrowing its space and overwhelming the garden. I quick glace around the garden will often highlight several candidates for division.
The tool of choice for this task is a spading fork, a tool that unfortunately most local gardeners have not yet discovered. A spading fork is not a pitchfork. It has thicker, shorter and stronger tines, a shorter shaft and a D-shaped handle. A standard round-point shovel can work in a pinch. However, the beauty of a spading fork is that it allows you to dig under a clump of vegetation and remove it without severing too many of the roots, which hang through the tines.
Although you may be able to divide a large clumping plants into a dozen sections or more, remember that the smaller the section, the longer it may take to mature, and bloom again. How often to divide a plant depends on how fast the clump expands. Vigorous growers, such as fortnight lily (Dietes) and Red Fountain Grass (Pennisetum), often need dividing every two to three years. Slower plants, such as bird of paradise (Strelitzia) or Clivia may only need a division every ten years.
If a plant is blooming poorly, has a lot of dead wood in the center, or is cramped and pushing out of the soil, it’s time to divide. If the plant appears vigorous and is blooming, wait.
A day or two before your chore, moisten the soil around the plant thoroughly, so you can dig more easily. Most clumping plants should be cut back rather severely prior to dividing. This step will frieghten a novice more than almost anything else, but clumping plants almost universally respond to hard cut-back very well. This cutting back, usually to a few inches of the soil, helps the plant better sustain the trauma of the digging and dividing as well as making the job easier for the gardener.
After cutting the plant back, use your spading fork or shovel to cut a circle into the soil around the plant, a bit past its perimeter. Once the plant is out of the ground, gently remove some soil from the rootball. Bulbing or tuberous plants, such as society garlic, agapanthus, daylily and clivia are easier to divide if you remove all the soil from their roots.
Plants can be broken into sections with a spading fork, shovel, knife, saw or pruning shears. For smaller clumps I prefer to use my hands, seperating the divisions at thier natural breaking points. Plants that have tough, sturdy roots, like daylily or fortnight lily (Moraea), usually need to be cut or sawed apart. Brittle or delicate roots (Clivia) need gentler handling.
When replanting the divisions treat them much like a new plant you are planting from the nursery. Prepare the planting area using soil amendments, a balanced organic fertilizer and perhaps gypsum. Replant the divisions immediately. To allow for settling, plant the divisions about 1/2 inch higher than the level at which they were originally growing. Give the planting a very thorough soaking and fill in with additional soil if settling occurs, but being careful to keep the replanted divisions at or above the surrounding soil. Keep the soil moist over the next few weeks as the roots venture back out into the soil and fresh top growth begins.
An overgrown plant, once divided and replanted will often burst out of the soil with new foliage surprisingly quickly. You may be surprised that by spring the newly divided plants are better than ever; with healthy new growth and abundant flowers, not the tired old clump that only a few months earlier was full of dead, brown foliage and only a few flowers.
Ron Vanderhoff is the Nursery Manager at Roger’s Gardens, Corona del Mar