Raised bed gardening may seem like it’s only for small-scale home gardeners, but the small farmer and homesteader will find that raised bed gardening has benefits for larger-scale production as well.
Benefits of Raised Beds
If you have poor, rocky soil or live in an area that has a high water table or overzealous rainfall, raised beds can solve your drainage and soil fertility issues. Some raised beds use the natural soil on the ground, while others are built empty and filled with a mix.
Raised beds allow the soil to warm more quickly in spring. The soil is never walked on, so it doesn’t get compacted. Weeds can be less of a problem in raised beds, especially if you start with a weed-free soil mix.
You can grow just about any plant in a raised bed: fruits like strawberries, blueberries, and raspberries; vegetables, herbs, and flowers.
Elevating a garden above the ground is a smart idea for several reasons:
- It’s a solution in areas with poor soil, like heavy clay.
- A raised garden is easier to work on and can ease the stress on the back, joints, and muscles that some gardeners experience.
- It can bring a garden closer to one’s living space, making it easier to access and maintain.
- Raised beds are an attractive way to contain a garden and add height to a small outdoor space.
- Irrigation can be customized for each bed, depending on the plants’ growing needs and locations. Drip systems can be installed, or you can simply hand water with a hose.
Materials for Raised Beds
The simplest raised beds are mounds of soil piled several inches higher than the surrounding terrain. They don’t even need sides! Many small farmers use this type of raised bed or raised row gardening to help soil drain more quickly and to add additional amendments to the top inches of soil for shallow crops and to help seedlings get established better.
But many gardeners opt for beds that are built with sides. These sides can be made of wood, stone or cement. It’s really a matter of what is least costly for you and what you have available.
Cedar is a great wood for raised beds because it is rot-resistant. Hemlock is a less costly alternative that also works well (my beds are made of hemlock). Juniper and redwood are other common wood choices. Do not use pressure-treated wood for your beds, as it may leach toxic chemicals into the soil.
Other options include concrete blocks, natural stone, or brick. You can also use boards made of recycled plastic like those that are used for decks and other outdoor structures.
You can also use bales of hay or straw as sides for your raised beds. The straw will decompose after a season, but you can move it to the compost pile and use new bales the next year.
The Best Materials for Building a Raised Bed
- Wood: The simplest and easiest way to construct a raised bed is with wood—experienced do-it-yourselfers can build one in a few hours or less, depending on the size and complexity of the bed. Recommended woods include weather- and rot-resistant types such as redwood, cedar, cypress, composite, or some pressure-treated lumber that has been approved or rated for ground contact. Stay away from wood that has been treated with creosote (like railroad ties) or pentachlorophenol, because these are chemicals that can leach into the soil—especially harmful if you are growing vegetables or herbs.
- Brick: While brick is more difficult to work with—especially for the novice—it helps tie together other areas of the landscape or exterior of a house that also use brick: stairs, patios, pathways, the facade. For a sturdy raised bed made of bricks, a concrete footing or foundation must be built for them to rest or be placed on. Mortar will need to be used between bricks to hold in soil and moisture.
- Stones or broken concrete: For a rustic or natural look, raised beds made of flagstone, dry-stacked rocks or pieces of broken concrete are an informal and sometimes economical alternative. If a bed is low in height (2 feet or so), mortar won’t need to be used to adhere pieces together.
- Masonry beds: Another bedding choice is a modular masonry system, usually available in different styles, sizes, and weights. These are a good choice for smaller, freestanding beds. Most feature interlocking concrete pieces to hold them together.
Most plants and warm-season vegetables will need at least six hours of sunlight per day, so keep this in mind when you are in the planning stages of building a raised bed. Rectangular beds should be oriented with their long sides running north and south to capture the maximum amount of daily rays.
An advantage to finding a sunny location: organically rich soil warms up quickly, produces a more bountiful crop of veggies and herbs, and provides better drainage.
Size of Raised Beds
Unless you plan on climbing into the bed to pull weeds and dig in the soil, design a raised bed so that it is about an arm’s length in depth (or width), which would be about 4 feet, Since the point is to elevate the gardening space off the ground, plan on a minimum of 10 inches in height. If the edge of the bed will also serve as an outdoor bench, plan on building it 18 inches from the ground. The length will be determined by the amount of space in your yard or on your patio, but 8 to 10 feet is ideal.
For multiple beds, design paths between them to measure at least 2 feet wide.
You may be wondering what size to make your raised beds. The determining factor is that you need to be able to access the beds from all sides. Three to four feet wide is ideal. Technically, raised beds can be as long as you want them to be. But limiting raised beds to 8 to 24 feet long makes it easy to practice crop rotation because each crop can be rotated to a completely new bed. This can inhibit insect pests that may spread diseases through the soil in one long bed.
Raised beds should be at least 6 inches deep and up to 36 inches deep. If you have good soil beneath the beds, roots will reach into that soil and continue to grow.
How Many Raised Beds?
The number of raised beds is limited only by your budget and is determined by your desired yield. If you are a homesteader seeking food self-sufficiency, a rough guide is 700 square feet of growing space per person. A market gardener would use even more. If you create beds 4 feet wide by 25 feet long, that would mean 7 raised beds per person in the family. For raised beds that are 4 feet wide by 8 feet long (a very standard size) that would be 22 beds per person.
That’s just a very rough guideline. So you can see that if you are going to want to use raised beds to grow food in quantity, you will need to create quite a few of them! Don’t feel daunted. You can add a few raised beds every season and continue to grow crops in the ground in the meantime. But if raised beds are your only option for growing, just make the investment of time, labor, and money, and enjoy the rewards for many seasons. The key is to build beds for the next season in the summer or fall, not in the spring. Sow a cover crop for over the winter. Come spring, you can cut the cover crops and add them to the compost, cultivate the existing soil in the beds, and plant.
One of the perks of having a raised bed in your yard is the possibility of controlling the wildlife that munches on and destroys your prized plants. Have you ever grown big, red tomatoes, letting them get redder and riper on the vine, only to go outside one morning to find that some discriminating creature has taken a bite out of it, probably spit it out, then went on to see what else is being offered at your backyard buffet?
To keep your beds low maintenance, choose plants that are disease resistant and are not attractive to animals and insects. Maintain a healthy garden by using fertile soil, the right amount of fertilizer, irrigation, and sun or shade. Group together plants with similar needs.
Before resorting to pesticides (often the last resort), try using organic methods, like barriers, a good blast from the hose, or sprays made from non-toxic household products.
- Gophers, moles, and ground squirrels: These underground miscreants can tunnel through the .soil, munching on bulbs and shoots. If this scenario occurs in your raised bed, place root balls in wire cages or line planting holes with barriers of hardware cloth.
- Snails and slugs: Use 3-inch-high copper bands to enclose vegetable and flower beds. Believe it or not, the copper emits a small electrical shock when a snail or slug touches it, making it retreat (not enough to kill it). Another method is to fill a shallow bowl with beer, dig a small hole so that the bowl’s lip is flush with the top of the soil. Snails and slugs are attracted to the beer, will go swimming in it, and drown.
- Flying and crawling insects: Protect vegetable leaves from flying and crawling insects by covering them with gauze. Find it at garden centers or online retailers.
One of the advantages of building a raised bed is to create an environment with great soil—something that is not often found in the ground where we live. It’s kind of like starting out fresh, with new, clean soil and amendments to grow an abundance of vegetables and flowers. You can use a planting mix or topsoil, and some places will deliver it.
If your property is blessed with good soil, use some of it in the raised bed, mixing in equal parts of the soil and organic matter such as compost.