If you’ve been thinking of building raised beds in your garden, now may be the time to do so. There are many advantages to gardening in raised beds. Not only do they cut down on the number of weeds you’ll have to contend with, they also drain more easily that in-ground beds, receive more exposure to the sun than them (and thereby warm the soil faster in the spring), experience higher harvest yields due to their closer spacing of crops, and make it easier to install row covers to extend your growing season and prevent birds, bugs, and other pests from stealing your produce. The greatest benefit of raised beds, however, is that they make gardening easier on the body — you’ll have to do a lot less bending and stretching on the ground when pulling weeds, planting, and harvesting from them.
What You'll Need
Raised beds can be made from a variety of materials, including rocks, bricks, concrete, and lumber. Lumber is the most commonly used material. If you’re planning to go that route, you'll want to avoid pressure-treated lumber and creosote-treated railroad ties, especially if you're going to be planting any edibles in your raised beds. Instead, use cedar or redwood, both of which are naturally resistant to rot.
Purchase the necessary materials ahead of time, and you might be able to build your raised beds within a single weekend.
Plan Your Garden Bed
Planning the construction of your raised bed ahead of time will ensure it’s done right. Don’t make the bed any larger than you can reasonably work and stretch. You don’t want to have to overextend to reach your crops. Ideally, three feet wide by six feet long and about two feet tall is a good size. You can make it shorter, but if you plan to grow root crops like carrots, a greater height will guarantee that you give them the room they need to grow. Also, consider building more than one bed at a time so you can rotate your crops each year and cut down on pests and diseases.
Prepare the Site
Before you start building, observe the area until you find a spot that’s relatively flat. Although you’ll have to dig down about six inches to a foot and flatten the soil within the resulting trench, finding a spot that's already flat will significantly reduce the amount of work you'll have to do.
Pull the turf and weeds from the site before you start digging. Then, mark the area off with string or chalk, and begin digging your trench. You’ll want to keep a few things in mind while doing this. First, if you’re building more than one raised bed, plan to have about two feet between each one to make it easier to push a mower or wheelbarrow through. Second, if you’re placing the raised bed in an area that tends to hold a lot of water, fill the bottom of your trench (up to two inches) with gravel to help improve drainage.
Once you’ve dug your trench, lay landscape cloth down to prevent weeds from poking up through the soil. It's also a good idea to lay down a layer of hardware cloth, which is usually made of steel or another galvanized metal, to prevent gophers, voles, and other vermin from snacking on your crops.
Next, you’ll lay down the first layer of wood on the sides of the trenches and begin building your walls. Arrange the boards so that the end of one plank meets the side of the end of another, and do this around the entire rectangle. Then, add the next layer of wood over the base, and drill timber screws through the top layer into the bottom one.
One of the secrets to healthy plants is good drainage. Drill a few holes in each board, angling them all upward to encourage water to run out of them.
Continue adding levels of wood to the bed until you’ve reached the desired height. Once you’ve finished this, drive posts into each corner and halfway along each side to reinforce the structural integrity of the box. Otherwise, the outward pressure of the soil may eventually push these walls apart.
Fill Your Garden With Soil
If you’re building a raised bed now for spring planting, consider filling it with compost, topsoil, and rotted manure. Keep in mind that it’ll break down more between now and springtime. Rake the top smooth to ensure that it's spread evenly throughout the box. You can also layer the straw from chicken bedding over the top — the chicken manure will give nutrients to the soil and keep wind-borne weed seeds from settling on your new raised bed.
In the Spring…
When getting ready to plant in the springtime, you'll want to set up your irrigation system first, especially if you plan on using drip irrigation. Apply a fresh dressing of compost and well-rotted manure after planting, and add another layer after you’ve harvested your vegetables in the fall. Once you’ve planted your seeds, starts, and crops, apply a layer of mulch to the top of the soil to prevent the growth of weeds and help your garden bed retain moisture.