Raised beds are problem-solvers

Raising your garden above the ground can solve some of the most frustrating problems vegetable growers face. The easy-to-build beds pictured on these pages make it possible for plants to thrive where soil is poor, wildlife is hungry, or growing seasons are short.

Like big pots, raised beds filled with good soil mix overcome the problem of heavy or hard garden soil. Good soil means plants can be set closer together, making smaller areas more productive. Lining bottoms of beds with wire screening keeps out critters like moles and gophers; and beds can be fitted with PVC framework for bird netting, to keep deer and birds at bay.

Moreover, in cold-winter climates, raised beds are quick to warm up and can extend the growing season. And they limit back-bending labor--you can sit on the edge of a raised bed and garden in comfort.

If water shortages have kept your gardening to a minimum, a raised bed is also an ideal place to concentrate plants. While lightweight soil mixes do tend to dry out more quickly than open soil does, they allow roots to grow deeper, tapping into a larger moisture reservoir. And raised beds adapt well to drip irrigation.

Raised beds have a strong visual appeal; their regular shapes bring order and structure to a garden, turning an ordinary vegetable patch into an attractive focal point--an area where people want to go. The sides of the beds can be painted to match the house, and paths can be covered with anything from gravel to mulch--adding to their formality and keeping feet out of the mud.

September is a good month to plan and build raised beds, just in time to plant cool-season crops. In the mild-winter West, it's the best time to start a fall garden.

How to plan and build raised beds

Raised beds can be almost any size or shape, but there are some guidelines to keep in mind. If you make the beds more than 4 feet wide, it will be difficult to reach the middle from either side. When figuring the height of a bed to be built over poor soil, it's a good idea to allow for more than 12 inches of good soil.

For side that will double as benches, a height of 18 to 24 inches is easiest on the back and knees. (If you cap the top, use boards that are 2 to 3 inches longer than the sides to minimize overhang on the inside of the bed.)

If you build more than two beds, consider mixing shapes--using two squares and one rectangle, for example--for a more interesting pattern. Orient rectanular beds with long sides running north-south, so plants receive maximum sunlight. Paths between beds should be at least 24 inches wide.

Once you've decided on the number and placement of the beds, plan and install main irrigation lines.

For sturdiest beds, use lumber at least 2 inches thick; redwood, cedar, ad pressure-treated (see box at right) last longest. Most raised beds are just bottomless boxes, so the corners are the most important part of construction. You can simply nail the ends of the boards together, but lag-screwing 4-by-4s to the inside corners will make the box stronger. For ease in replacing rotted boards, one gardener we visited supports the sides of his raised garden with sections of 1-inch metal pipe pounded into the ground alongside the bed (see picture at left).

Corner posts don't need to be sunk into the ground, but the bed will be more secure if they are. Large timbers can be held together with metal corner braces. If you build a bed longer than 12 feet, nail the side boards to posts sunk midway along the lengths of the bed to prevent the boards from bowing outward.

Filling your raised bed with soil

The 4- by 10-foot, 20-inch-deep raised bed that we built holds ablut 2 1/2 cubic yards of soil. If you already have fairly good garden soil, you can fill your raised bed with a mix of equal parts soil and organic matter such as compost or ground bark. Or buy potting soil in bulk (look in the yellow pages under Topsoil).

You can also make your own lightweight soil mix, but it takes a lot of work. Container Gardening (Sunset Publishing Corporation, Menlo Park, Calif., 1984; $7.95) provides recipes for several container soils, including a basic lightweight mix, that work equally well in raised beds.

Before filling the bed, place 3 to 4 inches of new soil in the bottom and work it into the ground as well as you can. This will aid drainage and provide a transition between the two soils.

Which vegetables to grow in raised

beds; tips for keeping beds productive

Any vegetable can be grown in raised beds, even large plants like corn (see pages 140 and 141) and sprawling vines like cantaloupe or squash (see photo inset, page 140). Root crops such as carrots, onions, and beets grow especially well in raised beds' loose soil.

Like those in containers, vegetables grown in raised beds nned frequent applications of fertilizer, particularly nitrogen. This is especially important if you use a potting soil that is rich in organic matter. Fertilize before planting and then every two to three weeks according to rates on the product label. Feed less frequently as fruit-bearing plants like tomatoes begin to mature. Or, use a controlled-release fertilizer at planting time.

COPYRIGHT 1991 Sunset Publishing Corp.
COPYRIGHT 2004 Gale Group