A Complete Guide to Raised Bed Vegetable Gardens

My first vegetable garden was almost my last. I spent hours trying to loosen the native clay in my backyard, resorting to a pick axe when my shovel bounced off the dry, hard soil. (Later, I’d learn that sandy soils are also problematic, low in nutrients and too fast-draining.) I was ready to give up when I realized I could make a raised bed vegetable garden—or two—and lose the pick axe.

Benefits of Planting Vegetables In Raised Beds

Planting vegetables in raised beds is ideal whether you have clay, sandy soil or anything in between. They’re great for beginners or seasoned gardeners, says Amy Enfield, Senior Horticulturist at ScottsMiracle-Gro, because you can control the soil in them and the drainage is better than gardens in the ground. There are more advantages:

• Avoid difficult native soil: With a raised-bed garden, you can avoid dealing with difficult native soil, which is a gift when the native blend is hard clay or shale and tough to dig.
• Better drainage: Soil in raised beds drains better, which means wet weather won’t stall — or rot — crops
• Longer growing season: Soil in raised beds usually warms up faster than the ground, so you can plant earlier and enjoy a longer growing season.
• Less bending over: It’s easy to reach in to plant and harvest, so you don’t have to stoop as much.
• Fewer weeds: Growing plants close together helps suppress weeds.
• No foot traffic: The soil is less likely to compact because you’re not walking on it.
• Beautiful: They add aesthetic appeal, especially if you're creative with your planting designs.

Raised Bed Garden Tips: Getting Started

Scout the Right Location

Your first step, Amy says, is finding a location that gets at least 6 to eight hours of sunlight daily, although some veggies, like lettuce, can take less. Choose a spot with easy access to water; if it's not level, level it. Don’t put beds near big trees or bushes, where the roots will compete. Avoid using them on decks or other surfaces where the weight or water runoff could cause damage.

Choose the Size of the Bed

A good size is 4' to 8' long and 3' to 4' wide. “Raised beds can be as shallow as six inches deep, but beds 12" to 16" deep or more can grow bigger plants with deeper, more extensive root systems," she says. If one side of the bed touches a wall or fence, make it narrower so you can reach in all the way.

Plan the Layout

Use your imagination to choose materials, textures and shapes that complement your landscape. But be realistic — an elaborate design with several beds is considerably more work and maintenance than a couple of small beds placed side by side. Whatever design you choose, work it out on paper first.

Source the Edging Materials

Look for premade raised beds or kits, or use your own materials to build one. Avoid materials that may leach toxins into the soil, like railroad ties or painted wood. Some common raised-bed frame materials:

• Wood: Many gardeners prefer untreated wood for vegetable gardens. Cedar and redwood boards are naturally rot-resistant.
• Landscape 'timbers': These are made from recycled plastic, weather well and last a long time. Some are even manufactured to look like weathered wood.
• Decorative concrete block or stones: Blocks and stones are most often used to build retaining walls but also make excellent raised-bed frames. They're durable and you can stack them to varying heights to make tiered beds.
• Bales of Hay: Straw bales are especially useful for gardeners looking for an impermanent raised bed solution. As the straw decomposes, it adds nutrients to your garden.

How to Construct a Raised Bed Vegetable Garden

1. Prep the area. Remove grass and weeds from the ground where you’ll put the bed. Cover the area with thick, damp cardboard. Leave some space between beds to walk or where you’ll mow or push a wheelbarrow.
2. You can make an easy, frame-free bed. Pile some soil up to six inches high.
3. For a deeper bed, construct a frame. To secure wood or metal frames, Amy recommends driving stakes or rebar into the ground at each corner. Screw them to the frame or hammer them down.
4. Line the bottom of the bed. If the bottom of the bed sits directly on the ground, line it with hardware cloth or wire before filling it to discourage burrowing animals.
5. Fill the frame with soil. Figure out how much soil you’ll need by multiplying the length by the width by the height of the bed. For example, a 4’ x 8’ bed that is 8" high (or .67’), needs 21.44 cubic feet of soil. Fill the bed almost to the top, leaving an inch or so for water. Customize the soil as desired; use raised bed soil with fertilizer or mix your native soil with compost or other amendments. Rake the soil smooth and remove any debris.
6. Choose your seeds or plant starts. Add flowers and herbs, if desired, to attract pollinators (as a bonus, some will eat some insect pests). Consider companion planting, or growing plants that help each other grow and/or discourage pests.
7. Install irrigation and trellises or supports: Before planting, install any drip irrigation or drip hoses you want to use. It's better to water plants at their roots rather than from overhead; wet foliage can become diseased. Also, add trellises or other supports for vining and climbing plants, so you won’t harm the roots later.
8. Wait until the right weather to plant. Wait until the weather is warm enough to plant as indicated on your seed packets or plant labels. Amy says, "Cool-season crops including broccoli, spinach, and radishes should be planted about three weeks before the last frost date while warm-season crops like tomatoes, peppers, and basil should be planted about two weeks after the last frost date when both day and night temperatures are consistently above 50 degrees F."
9. Plant your seeds a little closer than usual. Follow the spacing directions on your packets or tags. You can often plant a little closer because you won’t be walking in the beds.
10. Water and mulch after planting. Water thoroughly after planting and add mulch. Don’t mulch over seeds, as this can interfere with germination.
11. 1 month later, apply fertilizer. About a month after planting, apply a slow-release fertilizer. Follow label directions.

More Tips for a Raised Bed Vegetable Garden

Grow Plants for Your Zone

For best results, grow varieties recommended for your USDA gardening zone. Test your soil pH (or send a soil sample to an extension service lab for testing) and adjust it as needed for the plants you want to grow. Ideally, test in the fall or when you start a new bed. Retest every few years and amend the pH, if needed.

Test the Soil Temperature

Not sure it’s warm enough to plant? Use a soil thermometer to check the temperature in your raised bed vegetable garden.

Harden Off Seedlings Before Transplanting

Harden off your seedlings before you transplant them into the ground; this involves moving them outside into a sheltered spot and gradually exposing them to a little more sun each day. Hardening off also helps them adapt to other weather conditions, like wind and rain.

Maintaining A Raised Bed Vegetable Garden

Stave Off Pests and Diseases

Treat pests and diseases as soon as you see them. After the growing season, remove and compost all plant parts. Discard anything with signs of pests or diseases.

Water and Mulch

Most vegetables need at least an inch of water per week, so apply water if there’s not enough rain. In hot weather, plants may need more. Reapply mulch as needed, but remember not to mulch over seeds that haven’t sprouted.

Rotate Your Crops

Don’t grow vegetables from the same botanical family in the same spot for at least 3 years. This helps break the cycles of pests and diseases and replenishes soil nutrients.

Vegetables to Grow In Raised Beds

You may want to devote an entire bed to sprawling plants like watermelons or let them trail over the sides of the beds, so they don’t take up too much space. Some vegetables, such as corn and asparagus, don't usually do well in raised beds.

Tomatoes. Start tomato seeds indoors 6 to 8 weeks before your last anticipated spring frost. Transplant seedlings or set out starts about 2 weeks after that date. Plant young tomato plants deeply and roots will form along the buried stems. Cage or stake indeterminate types (tomatoes that grow and produce fruit until frost. Determinate tomatoes grow to a certain height and stop). Amy recommends growing companion plants like basil to help repel aphids and enhance flavor; marigolds deter nematodes and other pests.

Peppers. These sun-lovers take 60 to 90 days to mature, so sow pepper seeds indoors 8 to 10 weeks before your last anticipated spring frost. Transplant seedlings or set out starts after all chance of frost and nighttime temperatures are above 55 degrees F.

Summer Squash. Direct sow squash seeds after your last expected spring frost. Plant starts after the last frost and when the soil is at least 60 degrees F. Harvest when the squash are small and the skins are tender. Grow beans as companion plants for squash; they’ll fix nitrogen in the soil, Amy says.

Melons. Sow melon seeds indoors 3 to 4 weeks before your last anticipated spring frost and transplant them, or set out starts, when the weather is at least 70 degrees F. You can also direct sow outside in hills or mounds 2 weeks after the last spring frost. Thin to the strongest plant on each hill.

Beans and peas. Sow beans directly outdoors after the soil is at least 60 degrees F. Sow peas 3 or 4 weeks before your last expected frost. Grow squash as companion plants to shade the soil, help prevent weeds and retain moisture.

Beets and carrots. Most root crops need soil at least 12 inches deep. Direct sow carrot seeds and beet seeds and keep them moist. Grow onions as companion plants to repel carrot flies; Amy recommends growing dill with beets to attract helpful insects like ladybugs and wasps.

Potatoes and sweet potatoes. Potatoes are sensitive to cold, so wait until nighttime temperatures are over 50 degrees F. before planting. Plant seed potatoes 2 to 4 weeks, and sweet potato slips 3 to 4 weeks, before your last expected spring frost.

Eggplant. Start eggplant seeds indoors 7 to 10 weeks before your last average spring frost. Transplant them or plant starts after all frost danger has passed and the air and soil are at least 70 degrees F.

Cucumbers. Direct sow cucumber seeds or plant starts when the soil is at least 70 degrees F. Grow them along the bed edges and let the vines trail or train them to supports.