If You Can’t Beat It, Raise It

Raised beds create architecture in a garden.

An elegant raised bed garden becomes an architectural feature in a sunny corner of this yard. The beds are built from 2 x 12 lumber.

What is a raised bed? It’s a planting area on top of the ground that offers one huge benefit: You can avoid bad soil. It also improves drainage. With perfect drainage and a deep, rich soil, you’ll have a healthy, productive garden. If soggy soil, heavy clay, pure beach sand, or shallow bedrock keeps you from planting, by all means build a raised bed. If you are gardening on a slope, position the beds so that they run across the slope, not downhill.

The sides of beds can create structure for a pathway in a garden.

The aisles in this raised bed garden are wide enough to roll a wheelbarrow. The beds are built from synthetic decking material that will not rot; this type of decking is often made from recycled plastics.

Another reason to build a raised bed is to give your garden definition by creating neat edges. These beds can become a feature in your garden design, especially if you are the type of gardener who enjoys keeping your plants neatly groomed. Vegetables and herbs can be very pretty. Serious vegetable gardeners sometimes make their beds front and center, even have them take up the entire backyard. Some build beds in the front yard because it is the only sunny spot available. In this case, neatness is a priority.

Typically, the sides of raised beds are 8 to 12 inches deep, but they can be any depth that you want. Accessible beds for persons unable to bend or in a wheelchair should be raised to about 30 inches. Just remember that you will have to fill it, so the deeper the bed the more fill you’ll need, and if you don’t have a source of rotted leaf litter or compost, you’ll have to buy it.

Building a raised bed with lumber is affordable and easy.

This simple raised bed is made from standard lengths of lumber. The material in the paths is pea gravel.

If possible, begin by tilling and amending the native soil beneath your raised bed. In places where the soil is practically bedrock, don’t worry about tilling. Just build a little deeper.

Make your edges from an endless choice of materials: lumber, concrete block, timbers, logs, stone, or other materials available to you. In a large, flat area, you can simply mound soil without edging as long as you find that it is not washing away. Many coastal gardeners in flat areas where the soil is awfully sandy or wet just mound up the soil without building sides.

Never make your bed wider than your reach. Typically beds are 3 to 4 feet wide so that you can easily reach from the edge to the center from each side without stepping onto the growing area. Because raised beds are usually wider than the rows of a traditional garden, you’ll have fewer paths and more planting area. Be sure to plant the full width of the bed to maximize your yield.

Fill the Bed with the Best “Soil” You Can

Use the corners of a raised bed to attach fenceposts for a wire fence that will keep out animals.

Low metal fence posts on the outer corners of this raised bed anchor chicken wire to protect these bean plants from hungry rabbits. The bed is built from "railroad ties" made of recycled plastic. This is from the Master Gardener's Demonstration Vegetable Garden at the Huntsville Botanic Garden in Huntsville, Alabama.

Fill the bed with a soil mix that is rich and porous enough to let air get to the roots, and make sure it holds moisture while draining well. Whew, what is that? Rotted leaves and compost are ideal. If you can mix them with a little native soil, that is good. You can often buy excellent-quality garden soil in bags, but it will run up the project’s cost, so if your bed is large, also look for bulk sources of compost and leaf litter to mix with the bagged soil. If you look at the fine print, you’ll find that bagged soil is actually not soil at all, but typically a combination of composted materials and perhaps sphagnum peat moss.

Some municipalities will deliver composted leaves for a reasonable charge. If possible, include 1 part native soil to 3 parts amendments. Avoid native soil if you live in an area known for root-knot nematodes or verticillium and fusarium wilts, which are soil-borne enemies of tomatoes and other vegetables. Check with your regional extension agent if you are not sure about these in your area. Look on our resources page for a link to regional extension agents. Native soil could introduce these problems to your bed.

Unlike the layout of a farm-style garden that is tilled and reconfigured each time it is planted, your raised bed garden will keep the same layout season after season. Your paths become permanent. Minimize maintenance by using 3 to 4 sheets of newspaper covered by mulch to prevent weeds in the path. You can also put grass clippings, chopped leaves, and other compostable materials on the path. At the end of the season, add the decomposed material to the beds as soil amendment.

Enjoy your raised beds. They are a great way to increase the productivity of a garden and get lots of food from a small space.