Saratoga News Divide perennials now for new spring growth Tony Tomeo Almost all of our flowering perennials are now dormant until spring. Unless you plan on collecting seed, the spent blooms should have been removed. This is when division is done. Some perennials are divided to minimize crowding and to keep plants healthy. Many clumping plants that grow from rhizomes split into two rhizomes at each of last year's blooms. Eventually the plant becomes crowded and less productive. Agapanthus africanus and orientalis are classic examples of perennials that bloom well when young, but produce fewer flowers at maturity unless divided into smaller groups every three to five years. Various plants grow at different rates, so the frequency of division depends on how quickly they become crowded. African iris (Moraea), for example, may never require division. Division is done more commonly to increase the supply of plants. Healthy rhizomes of bearded iris can be doubled every year from one plant to eventually become an entire bed of the same variety. The iris in my yard are from a neighbor who divided more than enough for her yard and now gives them away to anyone who will give them a good home! Plants suitable for this form of propagation include Bergenia crassifolia, Agapanthus orientalis/africanus, coral bells, African iris, Shasta daisy, daylily, yarrow, New Zealand flax and bearded iris. Plants are divided by simply digging up the clump of rhizomes and pulling the individual plants apart. With deciduous plants, such as some of the daylilies, each small young rhizome is broken from the previous year's growth and replanted. Evergreen plants, such as New Zealand flax need to have older fading leaves removed. The old rhizome is also removed and discarded. The new rhizome is then planted just deep enough to support the plant. If larger new clumps are desired, several new plants can be planted in the same place. Bearded iris and some of the larger New Zealand flax should have their leaves cut to about half to minimize desiccation and a tattered appearance. These cut leaves will be quickly replaced in spring. Don't forget that it's also time to plant your cool season vegetables like cabbage, lettuce, Brussels sprouts, cauliflower, broccoli, onions, beets, carrots, radishes and peas as your summer vegetable plants are removed and mulched. Be sure to keep your garden clean and leaves raked; snails love autumn-planted vegetables. As tuberous begonias and dahlias begin their dormancy, allow the soil to dry. Too much water at this time may cause them to rot before they shed their vegetative growth. Flower of the Week: Chrysanthemum No flower says "It's Autumn!" better than the florist's Chrysanthemum or mum; Chrysanthemum morifolium. This is by far the most popular flower this time of year for bedding, containers and, of course, cutting. Although some flowers may rival its varied colors, ranging from white, yellow, orange, red, pink, bronze, purple and even brown, the range of flower forms and sizes is matched by no other species. Potted mums are available all year because they can be forced to bloom by the growers. No matter what time of year you acquire your plant, without forcing it will naturally bloom in late summer or autumn the next year. Mums purchased for fall decoration can be planted in the garden and treated as perennials. I actually have a white anemone flowered mum in my yard that I planted in 1990. When your potted mums are done blooming and the last of the flowers fade, remove them from the pot and tear the individual plants apart, leaving as much of the root system intact as possible. Smaller pots only have one plant in them. Either way, cut the plants back to about eight inches and plant in larger pots or in the ground in well-drained, highly organic soil. As new growth appears at the base of each plant, all the old growth can be completely removed. Plants regularly watered and fertilized will bloom again next year. Very large flowers can be produced by a process called disbudding. As your plant forms about four or five stems, all side shoots are removed so that these stems continue to grow and form one flower at the terminal end. The resulting flower will be so large that staking will be necessary. If a profusion of flowers is desired, the process known as pinching is employed. The first four or five stems resulting from cutting back the plant should have their tip removed when they are about six inches tall. Each resulting stem should likewise be pinched at six inches in height. This process should continue all summer, at which time the flower buds will be apparent. Fertilizing mums is a bit more involved than with other perennials. They like to be fed at the first sign of new growth in the spring and regularly after that. However, fertilizing must end about a month before first bloom, and the last feeding should be low in nitrogen. After flower color shows through the buds, fertilizing could interfere with the plant's lifecycle. The main insect pest associated with mums is the aphid. Many gardeners remedy this problem by spraying with lightly soapy water. Mums are easier to grow than most people realize. After enjoying their showy blooms this season, try planting them in your garden for another show next year! Tony Tomeo can be reached at 358-2574. [ Back to Contents Page | Saratoga News Home Page | Archives ] This article appeared in the Saratoga News, November 18, 1998. ©1998 Metro Publishing, Inc. All rights reserved.