Do you have a plan? Every serious gardener needs one -- a site plan -- a drawing of your property with every useful bit of information you can collect, from the potholes in the driveway to the direction of the prevailing wind, correctly noted. Fall or early winter is a good time to do this, when some of the brush has died down and you can see outlines clearly. Then, over the winter, while your garden is asleep and you are awake, make assessments and plan changes.

If you moved into a new home surrounded by a builder's bare lawn, a landscape design can help you become familiar with every aspect of the property. Once you have established plantings, it can help you keep track of plants and conditions, lay out changes, replace landscape elements that aren't doing what you wanted them to do, and effect repairs.

Hire someone to draw a plan for you, or you can do it yourself. A site map doesn't have to be elaborate or a beautiful drawing; it just has to be of use to you. It's easier, but not essential, to draw your plan on graph paper. Paper with a quarter-inch grid usually works well, with a scale of one foot to one-quarter inch. If your property is very large or very small, adjust the scale accordingly. The bigger the drawing is, the more detail you can include. Paper that's 18 inches by 24 inches is a good size. Draw in pencil so you can correct as necessary.

A few simple tools help -- a compass, an 18-inch ruler and mechanical pencils. You can use more elaborate supplies if you like, such as specialized templates and bendable rulers for drawing curves. Art supply stores should have everything you need. And, of course, if you enjoy puttering with computer graphics, use a simple computer program that will help you generate a drawing of your house located on your lot.

The first step is measuring. You might have been given a site or plat plan when you bought your property, and that can be a good starting point. It should have the property measurements on it and the dimensions of the house and other large structures. But, you'll need many more measurements. It helps to have two people, one at each end of the tape, or you can use a measuring wheel.

Once you have a rough outline of the property's dimensions, you can start adding the basic shapes. Here are some data you might want or need to have on the map:

* Buildings, including garages and sheds.

* Utility poles, power lines, and lighting elements, such as walkway lights.

* Gas and water lines.

* Drives and walkways.

* Porches, patios, and decks.

* Walls, fences, and gates.

* Doors and windows.

* Trees.

* Planting beds.

* Planters or containers.

* Play equipment.

* Water features, including streams, ponds, and swimming pools.

* Direction of prevailing winds.

* Directions of drainage.

* Topographical information, such as slopes.

* Soil types.

Some of these elements are obvious, but others will require a little research -- wind direction and drainage, for instance. Wind direction is something you will have to keep track of over time, keeping in mind that there may be seasonal changes.

For a sloping area, you may be fortunate enough that the slope is gentle and will accommodate a path. Steep slopes might require a retaining wall to control erosion and steps to get from the top to the bottom. Unless you have a contour map, done by a surveyor, illustrate slopes with an arrow and labeling.

If you've been gardening in one place for a while, you probably already know the soil characteristics -- where it's good loam and the location of clay deposits. If you don't, buy soil-sampling kits at a garden center, or check with your Cooperative Extension Service.

Begin your design by copying the plat plan, or an adaptation of it, onto paper. Then start adding the other elements. Use simple shapes and keep track of what all the lines mean -- label everything as you proceed. Use dotted or dashed lines to indicate different types of utilities, and make yourself a key. If you're creating a new landscape, or want to make lots of small changes or one big change to an existing landscape, you might want to put in all the information except the plantings. Then get several copies of the basic plan so you can draw different ideas on the copies. You can also use tracing paper over the basic outline to experiment with various designs.

When locating trees, draw a small circle for the trunk, then a larger one to indicate the canopy. If you have young trees, or no trees, it's still important to draw the mature canopy so you can visualize how much area the tree will shade when it is grown. Measure existing mature tree canopies by taking a radius from the trunk to the edge of the leaf spread on the ground. The size of the mature tree should be on the tag it came with from the garden center, or you can look it up in a plant book or on the Internet, as long as you know what kind of tree it is.

If you want to have fun with your drawing, you can use some of the techniques that professional designers use to distinguish certain features, like those illustrated above. For example, evergreen tree canopies are drawn in zigzag lines with an occasional outward spike. Deciduous tree canopies are smooth lines with an occasional inward spike. Drifts of flowers are indicated by free-form, amoebae-like shapes. Formal or clipped hedges are squared off, and informal hedges are made with a collection of interlocking circles. Fences are lines with tiny circles or squares to indicate posts. Underground features are noted with dotted lines and rocky areas are shaded zigzags.

Use colored pencils to identify soil types. Fill in the colors of existing or new plants. Color lightly so you don't obscure other features.

Even if your drawing is simple, the point is for you to have fun with it. Try drawing a fountain or hot tub. Remove a really big tree that's creating too much shade and design a sunny perennial garden. Paper and pencils are cheap, and paper plans are endlessly changeable. While your garden dozes, plan its brilliant future.

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.

A site plan, above, can show buildings drawn to scale, as well as prevailing seasonal winds, trees, water features and other landscape elements. Symbols, below, can be used to show different types of trees and shrubs.