When you work in a field for a long time, it can seem that the same things happen, day after day. But occasionally, it's a good idea to sit back and take a look at what has been going on. A couple of rainy days recently gave me some time to look over the topics of my roughly 400 columns and identify some new threads in the landscape fabric. For instance, I noticed an increasing desire in recent years for "natural" solutions to landscape opportunities and problems. Here is more on that topic and other topics of increasing current interest.
A few years ago, knowledge of native plants was confined mostly to horticulture education and a certain group of landscape professionals. But today, everyone seems to have "gone native" in appreciating plantings that fit the environment, plants that return reliably year after year and garden management that lets nature balance the equation.
Native plants are those that evolved with the animals that inhabited a region. A surprising number of plants popular in this area, and natives of the United States, aren't from around here, including Colorado spruce, Douglas fir and Southern magnolia. Trees native to this region would be hickory, oak, hemlock and loblolly pines (Pinus taeda). Flowers include black-eyed Susan and joe-pye weed, but not purple coneflower, which is native to the Rockies, or liatris, found in the Midwest. Indigenous plants usually need less care and watering under conditions they are used to, but some are more needy than others.
To find native plant sources, contact one of the local native plant societies: the Maryland Native Plant Society at www.mdflora.org, the Virginia Native Plant Society at www.vnps.org, the Botanical Society of Washington at www.botsoc.org or the North American Native Plant Society at www.nanps.org/index.shtml.
Annuals and Perennials
Annual plants, such as marigolds, impatiens, petunias and wax begonias, can be changed frequently and tend to be showy, with bright-colored flowers throughout the summer. Varieties of annuals are coming onto the market that haven't been seen since the Victorian era, such as beggars tick (Bidens species), English daisy (Bellis perennis) and passionflower vine (Passiflora).
But perennials -- non-woody, herbaceous plants that return year after year -- also have many advantages. Perennial borders, popular in England 200 years ago but not much recognized in the United States until recently, can be used to create a wide variety of styles in the garden, from natural meadows to formal manicured landscapes.
There are more perennials and a much wider selection of annuals available at garden centers and nurseries these days. Perennials are low-maintenance in that they needn't be planted every year, but they don't offer flowers from May to September and they still have to be divided, deadheaded, weeded, mulched, cut back and perhaps staked.
You can learn perennials by growing some. The challenge is to coordinate them for a sequence of blooms. Check out these books: "Continuous Bloom," by Pam Duthie (Ball Publishing, 2000); "Gardening with Perennials Month by Month," by Joseph Hudak (Timber Press, 1993); and "Gertrude Jekyll: The Making of a Garden," compiled by Cherry Lewis (Antique Collectors' Club, 2000).
Integrated Pest Management
Integrated pest management -- preventing pests from becoming a problem and saving toxic chemicals for a last resort -- has graduated from agriculture to gardening.
It starts with good planting practices, including clean tools, where the handles are sanded and oiled after cutting diseased wood and pruners are wiped with bleach and lightly oiled.
Integrated pest management also requires clean soil -- free of weeds, rock, construction debris and plants that might harbor insects or disease -- and native or well-adapted plants.
Techniques include refraining from planting related species next to each other (to discourage pests from spreading) and making sure plants are suited to their locations -- bog plants in wet areas, shade plants in shade and so on.
Good sources of information include your local agriculture cooperative extension office and www.csrees.usda.gov.
When leaves start falling, you may get a view of a neighbor's ugly shed or a busy road that wasn't visible when plants were full. Careful planting can disguise or hide eyesores and establish a natural boundary between parts of a garden or between property lines. Thoughtful planting can also bring winter interest to a garden that would otherwise be a wasteland of brown and dying flowers and bare brown branches.
Fences provide most landscape screening needs, but they have their disadvantages. They are limited in height in most locales, and they are sometimes limited in materials and design by local ordinances. They also screen out entire views, desirable as well as undesirable. Walls can be expensive and may face height restrictions.
Hedges, shrubs planted in a row to grow together into a dense barrier, are the most common natural screening method. A hedge can extend screening to almost any height. It can be uniform or varied, evergreen or deciduous. If you can wait a couple of years, and if you site evergreens properly, hedges form ornamental, low-maintenance, year-round screening.
Hedge plants must be installed far enough apart to become fairly mature before growing together. Leyland cypress, though not a very exciting plant because it offers no flowers or berries, is the fastest-growing, most popular evergreen screening shrub in this region. When installed on four-foot centers, the foliage of one plant will touch the leaves of the next in two years, but they will decline just as rapidly if they are not given a lot more room between plants. Leyland cypresses should be planted 8 to 10 feet apart to survive and must be kept wider on the bottom than the top to get full sun to all parts of the plant.
Other narrow-leaf evergreen shrubs for hedges are yew, juniper, falsecypress (Chamaecyparis species) and arborvitae. Most do not offer seasonal interest and are not very showy, but all will take some shearing and grow into tight barriers.
Conifers -- evergreen, needle-bearing trees, such as firs, pines and spruces -- usually grow tall in a pyramidal shape and need full sun. I like the Oriental spruce (Picea orientalis), and one fir tree that is most adaptable in this area, Nordmann fir (Abies nordmaniana). Japanese black pine (Pinus thunbergiana), which has a handsome sweeping, windblown look, makes a good windbreak and is known to be tolerant of salt air. A native deer-resistant screening shrub that has a blue-green color and strong vertical habit is Eastern red cedar (Juniperus virginiana).
Generally, I find broadleaf evergreen trees and shrubs more interesting as screening because they have flowers and berries or other showy fruits. Some examples are Nellie R. Stevens hollies, common boxwoods (Buxus sempervirens) and species cherry laurels (Prunus laurocerasus). Osmanthus will also create a formidable barrier visually and for security, as well as fragrance in flower. But you must give each plant room to develop. Determine its mature size and plant accordingly.
When it comes to interesting things to look at in the garden, winter isn't as much of an off-season as you might think. The contorted filbert, also known as Harry Lauder's walkingstick, has curved, contorted branches that make it exceedingly interesting when it's leafless. Other plants, interesting for their branch color, are red-twig dogwood, also called red-osier dogwood (Cornus sericea), and several varieties of Japanese maple.
Some plants bloom in cooler months. Winter flowering jasmine offers forsythia-like yellow flowers from January into March. Some varieties of witch hazel can have yellow or red February blooms. Hellebores are evergreen perennials that flower in winter. Early blooming bulbs such as blue and white glory-of-the-snow (Chionodoxa), yellow winter aconites (Eranthis) and snowdrops (Galanthus) must be planted in the fall.
Some shrubs and perennials are ornamental because they don't lose their foliage. Their leaves turn a showy red or orange and stay on the plant all winter. One example is the evergreen shrub nandina, also called heavenly bamboo. Its red foliage is often accompanied by long, drooping clusters of red berries. Another perennial that gets noticed in winter for its colorful leaves is bergenia. Its cabbage-textured foliage turns orange-red and stays that way into winter.
Joel M. Lerner is president of Environmental Design in Capitol View Park, Md. E-mail or contact him through his Web site, www.gardenlerner.com.