In my garden, a hillside of daylilies bursts into flower in early summer, and its three weeks of showy bloom provide the linchpin between all the pizzazz of the spring and the robust beauty of the late season.
The daylilies' sea of pastel yellows, pinks and purples is a key element in the landscape, flowering as it does during a lull, and so its retreat in the past two years has had a singularly deflating effect.
I tried to blame the demise on pests, a thrip or a mite, but I know deep down that the problem is my responsibility: The daylilies need dividing and now is the time to do it.
Many popular perennials crowd themselves out after a few years. What started out as a single plant becomes a clump of individuals, tripping over each other for the same light, soil and nutrients. No wonder they lose the will to flower.
Daylilies are among a group of perennials that cry out for dividing. Other commonly grown perennials that require this attention are hostas, bearded and Siberian irises, lamb's ears, various daisies and any perennial that grows ever larger as the number of flower stalks diminishes. One giveaway is a ring of new shoots around an ever-more vacant center.
Ornamental grasses dislike disturbance when in active growth and are best divided in early spring. Chrysanthemums should be divided in the spring as well, when the new growth is evident. Wait for spring to divide fall blooming perennials like asters, goldenrods and sedums so you don't set back plants that are about to flower.
Many perennials don't require dividing; if they continue to flower well year to year and appear uncrowded, leave them alone. Peonies are a good example. But if plants need a sunnier spot, or if they are in the way of a new planting, or if you want to make wholesale improvement to the soil in a bed, or if you simply want to split what you have to make more of them, dividing lets you do all that.
And now is the best time to do it.
Re-planted in the next two to three weeks, the separated pieces will have several weeks to grow and re-establish their roots in warm soil at a time of year when the plant concentrates naturally on this part of the life cycle. The fresh roots will anchor the perennial against winter frost heaving and produce vigorous new growth next spring.
The act of dividing the plant inevitably bruises and damages the leaves, but it doesn't matter now because their annual work of food-making is ending anyway. If you were to divide hostas in the spring after shoots grow, you run the risk of marring the leaf for the whole growing season. Some perennials will re-grow fresh leaves to replace damaged shoots, but why take the risk?
It may seem more work to dig up an entire clump than seek to pick at peripheral pieces, but it is more efficient this way. The divided perennials -- called divisions or increases in garden parlance -- consist of entire plants. The leaves may be expendable, but the other components are not: the roots, often the root- or bulb-like rhizomes, and the crown of the plant have to stay together to remain viable. It is much easier to examine the patients before surgery if you can see them, especially if you need to separate with a blade.
As a rule, I take a hose nozzle and wash off as much of the clinging soil as possible. This should also reveal the tiny buds at the base of this years' shoots that will grow next spring to bloom. They are important to keep and protect.
Some perennials can be separated by hand, including daylilies and bearded irises. Others with fibrous roots such as hostas need slicing with a sharp blade. An old serrated bread knife works well (or even a new one, if any cooks in the house are sufficiently distracted.)
Soaking the division in a 10 percent bleach solution for a few minutes will kill any lurking insects or fungal pathogens. In addition, I like to soak the division in a bucket of water to which a low nitrogen fertilizer has been added. My preference is for an organic feed of fish and seaweed extract, full of micronutrients.
Meanwhile, you can and should amend the bed where the divisions will be replanted by digging in organic matter.
Bearded irises, in particular, benefit from dividing and need to be divided more than most other common perennials to keep flowering well. Many iris fanciers do their dividing in the heat of August, though there is still time for re-planted irises to grow anchoring roots before ground freezing. Ginny Spoon, this region's vice president for the American Iris Society, said she likes to give iris beds a thin layer of pine fines, a soil-like mulch of pine bark, to help the roots to re-grow. She recommends dividing every three or four years, though irises that rebloom in the fall and those in deep soil need dividing less often.
When the irises are out of their beds, the gardener has a great opportunity to enrich the soil, and also to add some lime to raise the pH. Manure or other organic matter should be well incorporated into the soil and kept away from the rhizomes, which are prone to rot. The rhizomes are planted with their upper surfaces exposed to the air, and are not mulched.
It seems folly not to enrich the bed in which any newly divided perennials are being re-planted or re-located.
Peter J. Schenk Jr., a professional gardener in Alexandria, said he likes to add a product to heavy clay soil called PermaTill (available at garden centers, Web site www.permatill.com). This is a mineral-based soil lightener that doesn't break down in the way that humus does, he said. Water the divided plant.
The new division may not produce as many blooms as you would like next year, but it will the following years and should continue to do so for four or five more before it needs dividing again.
There is one hitch with dividing perennials: the dilemma of suddenly having too many. A clump of my daylilies produces 13 new plants. My hillside planting of 200 daylilies conceivably could generate 2,600 daylilies, which must be dealt with before an order of 3,000 spring bulbs arrives next month. It's going to be a long fall.
Ideally, you trade your divided perennials with friends and neighbors, and in small towns this becomes a late summer ritual. Other methods of dispersal include joining a plant society or garden club, which use members' divisions to hold sales and raise funds. Others with a perennial glut find takers on community listservs. Some people unabashedly sell their divisions, while others donate them to community beautification efforts.
I knew of one daylily hobbyist who, in a stroke of sheer genius, sold divisions to people who came to his place and dug them. Gleefully. In the driving rain. (My back still twinges.)
If you don't have a ready outlet for your surplus, Schenk points out, you can stick them in cheap nursery pots filled with a bit of topsoil, the containers grouped against a sheltered wall. This will allow you or others to plant them later, in the fall or next spring. Similarly, you could heel them into a vacant bed to be dug later, though this poses the risk of you forgetting about them.
As a last resort, you could toss them on the compost pile. Here, they will surreptitiously re-grow. One day you will go to get compost and find 800 hostas begging for attention. There are worse problems.