How to Build a Raised-Bed Garden

There are many ways to construct a raised-bed garden. Everybody Grows has adopted a simple method that we have detailed below. Happy gardening!

Step 1 – Materials

Lumber

Although the frame of a raised bed garden can be almost any width, we recommend a width of no more than 4 feet. This width allows most people to reach into the box from either side to plant, weed, fertilize, and harvest without stepping into the box and compacting the soil. Widths greater than 4 feet are often less manageable. And although the height of a raised bed frame can vary from 6 to 12 inches, we suggest that your frame be at least 8 inches high. This will allow it to hold the necessary soil to grow underground vegetables (such as potatoes) or to grow plants with deeper roots (such as tomatoes). In order to secure the corners of your frame, we recommend placing a 4 inch by 4 inch post in each corner, attaching all corners of the frame to the post. Including the posts will take a few inches of space away from planting, but your raised bed garden will last longer this way.

We recommend that your lumber be the following dimensions:

Two 12 feet (length) by 8 to 10 inches (height) by 2 inches (width) untreated wood boards (Although the length of a raised bed garden can be greater or shorter than 12 feet, we believe this length is ideal).
Two 4 feet (length) by 8 to 10 inches (height) by 2 inches (width) untreated wood boards (As indicated above, a width greater than 4 feet is not ideal).
Four 4 inch by 4 inch untreated wood posts, cut to the height of your boards i.e. either 8 or 10 inches

Although untreated lumber will not last as long as treated lumber, untreated lumber is better because there are no chemicals that could leach into the soil being used to grow your vegetables.

Newspaper/Cardboard

Killing the grass and weeds under your frame is essential. Although there are many products sold at the garden and home improvement stores to achieve this objective, we recommend that you use the less expensive and more widely available weed blocking materials: newspaper and/or cardboard.

An approximately 1/2 inch thick layer of newspaper is typically sufficient, although a thicker layer of newspaper or layers of cardboard are ideal. These materials work well because they are porous, preventing water from remaining inside your raised bed and drowning your plants. The newspaper and/or cardboard will break down over time and “compost” in place.

Hammer and Nails vs. Screws?

Although constructing a frame by drilling holes in the lumber and using screws to hold the frame to the corner posts will likely increase the longevity of the raised bed, you can also choose the easier method of using a hammer and nails.

In order to maximize the grip, we recommend using at least 4 inch nails and using at least 3-4 nails per connection.

Step 2 – Construction

CONSTRUCT THE FRAME

Nail or screw the 12 foot in length lumber onto the 4 inch by 4 inch post. Then, nail or screw the 4 foot length lumber to the same 4 inch by 4 inch post. Try not to split the lumber. Splitting is less likely if you do not nail or screw close to the edge, and instead place your nails into the center of the lumber.

LAY THE NEWSPAPER OR CARDBOARD

We suggest cutting the grass before placing the newspaper on the ground. The newspaper should extend slightly beyond the frame, to help avoid grasses and weeds growing into your gardening space from the outside. Finally, we recommend wetting the newspaper or cardboard before adding the soil.

ADD SOIL

The key to the success of your raised bed garden is your soil. One of the advantages of a raised bed garden is being able to improve your soil each year so don’t be discouraged if it is not at it’s best the first time around!

We recommend that at least one half of your soil be compost, preferably a locally “grown” compost, and the other half be a mixture of potting soil and coconut coir, along with some worm castings and rice hulls. Although we generally mix all of the above ingredients, think of your base as compost and your top layer being primarily potting soil and coconut coir.

There are several companies in our area that sell compost in bulk, and we have successfully used the standard compost mix from Veterans Compost, a company that makes compost from food waste in DC, suburban Maryland and Virginia. If you are buying your compost in bags, mixing different brands can be beneficial, as different brands contain different sources of nutrients. Leafgro is a locally produced, high quality, and reasonably priced compost.

The top half of our recommended mix consists mostly of potting soil (filtered top soil works as well) and coconut coir. Coconut coir (ground husks of coconuts) is sold in a compressed form and you will need to add water and allow it to expand in order to be able to break it up into “soil”. In addition, we recommend adding a bag of rice hulls and some worm castings, which together will help both aerate and fertilize your soil.

The total amount of soil to be added to your raised bed depends on the size and depth of your raised bed and the plants you intend to grow. If you are growing more deep rooted vegetables, such as tomatoes, you will want to fill your raised bed to the brim. To calculate the volume/amount of soil you will need, multiply the length by the width by the depth of your raised bed, thereby calculating the total cubic feet of the space. Check out cubic feet calculators such as this soil calculator that will allow you to easily make this determination.

CARING FOR PLANTS

With good soil, sufficient water, and ample sunshine, most vegetables will prosper and supply the gardener with food. But every type of vegetable has its own peculiar characteristics and there is no single formula for proper care and maintenance.

Caring for Your Plants

WATERING

Most vegetables should be watered either early in the morning or late in the day. When plants are watered in the middle of the day, particularly in the hot Washington D.C. summer, much of the water will simply evaporate and not reach their intended target: the roots of the plant. It is best to make sure that plants receive enough water to go deeply into the soil. It is also better to water once or twice a week, rather than watering lightly every day. This is because most vegetables prefer not to have their roots remain wet for extended periods.

FERTILIZING

If you planted in rich soil, your plants should not require repeated application of fertilizer. However, several types of vegetables, such as tomatoes, are heavy feeders and can use additional fertilizer when fruiting. Other plants that have long summer growing seasons , such a squash, beans, corn, or peppers, and can also benefit with “top dressings” of compost or other organic matter during a hot summer growing season. “Top dressing” means mixing the organic matter into the top layer of soil around the base of the plant.

REDUCING PESTS

Different types of pests are attracted to different types of vegetables. Although there is no “one size fits all” method of dealing with pests, certain types of vegetables and flowers actually repel the pests that are attracted to other types of vegetables and flowers. Thus, we try “companion planting” or “family planting,” where we place plants that tend to help each other near one another. Many garden catalogs describe these interactions and we can help provide more information on request. Newly, our winter garden intern Lea researched local pests and pest management so reach out to us to get access to what she worked on as well.

REDUCING WEEDS

No matter where or how you garden, you are likely to have weeds. Pulling weeds is simply part of the gardening experience. However, there are several ways to reduce weeds and thereby reduce the time spent pulling them. First, planting vegetables closer together (than indicated on seed packets for instance) and thinning the excess plants (those that are too close and competing with one another) will shade the soil and reduce weed growth. Second, using a layer of mulch around the base of the plant, assuming the mulch used is clean of weed and weed seeds, will suppress weeds. Finally, when pulling weeds, make sure to dig deeply in order to remove the weed’s roots. Otherwise, the weed will simply grow back and sprout new weeds.

How to Build a Container Garden

There is good news for people who live in apartments, have outdoor areas with more concrete than soil, you can still have a wonderful vegetable garden, using containers.