Special to The Washington Post

Preparing the soil

Organic material is the most difficult substance to keep in your soil; living organisms are constantly digesting it. Topsoil high in organic material releases soil nutrients, holds moisture, assists drainage, and helps flora develop stronger roots and stems to fight disease more effectively.

To improve your soil, till in well-aged homemade or commercial compost, such as Leaf Gro. Add three to four inches of well-composted material to enrich earth that has never been tilled. Incorporate compost to 12 to 16 inches deep. At least 20 percent organic material by volume will create healthy garden loam.

Monthly applications of water-soluble fertilizers benefit annuals greatly, and applications of slow-release fertilizers when planting. However, it's best to err on the side of less synthetic fertilizer on shrubs, trees and perennials to reduce the chance of nutrient runoff into streams, rivers and bays.

Getting and dividing plants

Most people don't think about their garden as a nursery, but most perennials and some shrubs can be divided and spread around the garden. Many perennials grow quickly and could be ready to divide in three to five years.

If bearded irises are dug every few years and one-year-old rhizomes are transplanted in late summer after blooming has stopped, they have a better chance of avoiding iris borer and root-rot problems.

Divide peony rhizomes in fall only if you want more of them. To ensure flowering, transplant roots so buds are less than an inch deep.

Daylilies don't need dividing, but as clumps enlarge and emerge, slice off pieces and move to other sunny locations.

Pieces of autumn joy sedum roots can be sliced off clumps and transplanted, as well. Do the same with hostas.

Black-eyed Susans seed themselves, naturalizing quickly. Young seedlings can be dug and moved to other locations. Gaillardia similarly self-seeds.

Divide ornamental grasses in spring.

Some shrubs will grow roots where their stems touch the ground. Each rooted branch can be pruned from its parent, dug and transplanted. Azalea, forsythia, weigela, and winter jasmine are a few examples. Nandina and other shrubs that grow vertically with canes or tend to spread by suckers and seedlings like lilac and crape myrtle should be dug with enough roots for transplanting.

Planting, transplanting

Flora already growing is generally available either balled and wrapped in burlap or in containers at garden and home-improvement centers. Plants are also available by mail order and may arrive with bare roots.

Be sure you have excellent soil moisture when digging - not too wet or muddy. Don't dig if soil sticks together in your hands.

The tool for digging, planting, dividing and many other garden tasks is a square, straight-edged garden or nursery shovel. I prefer a heavy steel blade, about 14 inches long, with a 27-inch D-grip steel handle. A heavy tool like this does the work for you.

Transplant when the soil is slightly moist, slicing down deeply, cutting through roots around the base. Dig down with the nursery shovel at a slight angle toward the root ball.

Don't pry roots. Dig down about eight inches, then slice diagonally under the roots. Do this all the way around the plant to form a ball. Once you have sliced deeply under the plant, start to lift it. If possible, use two nursery shovels, one person on each one.

Dig planting holes two to four times as wide as the base of root balls and no deeper than the height of the root ball.

Pruning

To keep your garden looking pruned but natural, you might have to confront some unnatural plantings and take some drastic measures. Selectively pruning a plant is the only way for it to grow the way you want it to.

Renew formally planted shrubs growing beyond their boundaries before growth begins in spring. They will grow back better with a more natural-looking habit.

Deciduous shrubs that flower in spring will need to be pruned during the growing season. The best time is immediately after flowering, or you sacrifice some flowers the next year. This is also true for spring-flowering broadleaf evergreens such as azalea, rhododendron and camellia.

Never prune when plants are wet, which can spread disease. Don't hard-prune any newly installed shrubs or trees.

Composting

Composting can be as simple as a pile in your yard, or you can create a container made from wire mesh, block or wooden slats.

A variety of manufactured bins are also available. Make sure that one side of the container is removable, providing easy access to the compost.

Air circulation is vital to the bacteria that break down plant material. Air, heat and moisture are needed for composting. Managing these basic requirements can maximize the efficiency of the process.

Here are some suggestions to encourage the breakdown of organic materials, but all organic material will eventually decay, even if your mix isn't quite right.

Maintain a much higher ratio of carbon than nitrogen in your compost pile, and mix well.

Carbon comes from dry leaves and wood chips, while nitrogen comes from herbaceous and leafy materials such as grass clippings. Too little nitrogen will slow the composting process; too much will generate ammonia gas and the unpleasant odors that come with it.

Many variations work, but try to add at least half brown matter, such as leaves, twigs and straw, and a quarter to one-third green material, such as grass, weeds, flowers, manure, coffee and tea grounds, and waste from fresh fruits and vegetables. The last quarter or so can consist of existing compost and topsoil, to ensure that all of the requisite organisms will be in the pile. Layer materials and, as you moisten and turn the pile, mix evenly. Don't include cooked food, grease or diseased plants. Do not compost animal wastes of any kind. This will attract dogs, rodents and raccoons.

Water the pile weekly, particularly during dry periods. Determine moisture content by squeezing a handful of the composting material. It should feel like a well-wrung sponge. If it is too wet, turn or add dry materials.

Compost is ready to use when it is black or dark brown and crumbly and smells neutral to musty. Under proper conditions - full sun, air and moisture - this can happen as quickly as one to two months.

Joel M. Lerner is president of Environmental Design in Capitol View Park, Md. Contact him through his Web site, www.gardenlerner.com