One spring, after seemingly endless days of rain, my husband took a walk out to the vegetable garden. It’s 150 feet away from the house at the bottom of a sunny slope. And, it was filled with standing water. “I don’t think I want to do this anymore,” he said with a sigh. .

I always sowed the seeds and transplanted the veggies, but that garden was his domain and he liked maintaining it. My first thought was “oh, no!” The 55- by 22-foot space had supplied us with countless tomatoes, peppers, squash, peas, beans, lettuce, and so much more. I could have transformed it into a rain garden, but I loved the fresh vegetables and herbs.

That’s when I decided we needed raised beds. Now our edibles grow in six troughs and two beds edged with large timbers. Pea gravel paths keep our feet dry while we walk around the beds. It was the best decision ever.

 

High and dry

The soil in raised beds warms up quickly in spring and we no longer worry about sinking in the mud. Raised beds drain quickly, allowing you to plant sooner than you might if you were planting directly into the ground. At ground level, the soil in spring can remain cold and wet much longer than that of a raised bed. The metal troughs have a drainage hole at the bottom along the side, so when a thunderstorm hits, the excess water drains away.

Width versus length

A raised bed can be as long as you like, but should be no more than 4 feet across. Any wider than that and you’ll be stepping or kneeling on the soil to reach the plants. That causes soil compaction—not good for roots. A raised bed can be as simple as a row of slightly mounded soil, 4 to 12 inches high in the middle. Or you can use untreated wood timbers, concrete blocks, Corten steel, or flat stones, building your bed 1 to 3 feet tall.

Layout

The beds can be straight, L-shaped, or curved, making them an interesting part of a garden design. The least expensive way to create a raised bed is to simply mark the area (use orange landscape spray paint, or stakes and twine, or hoses or ropes along the perimeter of the planned bed). If the area currently holds grass, it can be cut away and turned upside down to rot in place. Rake the soil from the sides to make the length of the bed higher than the flanking paths. You can also add pulverized topsoil and compost to raise the bed if your soil is mostly clay.

Animal troughs—the real thing from farm supply stores—or a do-it-yourself small metal trough from a garden center work well. Because the metal heats up in the sun, plants should be placed a few inches in and away from the sides. If you opt for timbers (preferably untreated, rot-resistant cedar or fir) or landscape stones, level the area first.

Raised bed kits with 4-inch-tall wood planks sold at chain stores are typically good for shallow-rooted vegetables only, like radishes and lettuce. Unless you dig down 8 to 12 inches and amend that soil before placing the wood surround, simply adding 4 inches of soil will not meet the needs of a tomato plant whose roots can go down a foot or more.

Fill it

In beds contained by wood, stone, or a steel surround, it’s helpful to place permeable landscape fabric in the bottom to prevent perennial weeds from making their way up. Some gardeners also staple the fabric along the inside of the bed to keep soil from spilling out between the stones or wood when watered.

Clay garden soils are far too heavy and dense for raised beds and easily become waterlogged. When that happens, leaves turn yellow, the roots can’t get air or nutrients, plant growth slows, and the roots may rot. To fill raised beds, I use a mix of one-third pulverized topsoil and two-thirds compost. I’ll mix in a few shovelfuls of coarse sand and peat moss along with a little perlite or vermiculite (soil amendments). Everything gets mixed in a wheelbarrow before it’s added to the beds. These items are all sold at garden centers and chain stores. Not interested in making your own soil mix? Some garden centers offer bagged “organic soil” specifically for use in raised beds.

To cut down on the first-time cost of filling a raised bed, some gardeners turn to Hugelkultur. It’s German for “hill mound” or “mound culture” and is a long-time practice of using buried twigs, branches, and organic matter to create the base of a raised bed. A shallow mound is dug and filled with the rotting material and covered with soil; the idea is that this bottom layer will act like a sponge and eventually break down, adding nutrients to the soil. However, as the materials break down, they tie up nitrogen, which the vegetables need. And some things, like walnut tree branches, can inhibit plant growth. As the materials eventually decompose, the surface drops and you’ll need to add more soil. 

Nina Koziol is a garden writer and horticulturist who lives and gardens in Palos Park, Illinois