Materials to Frame the Bed
The gardens are going to be outside, so consider weather resistance in the materials you select. You can buy complete raised bed kits, including the boards, corners and anchors all in one box. You will probably need a Phillips-head screwdriver to screw the corner pieces in and a mallet or hammer to drive the anchors into the ground. The downside to most commercial kits is the depth of bed – most are 6 inches deep, a minimum for healthy roots, but some kits are only 4 inches in depth, which is a little shallow for many vegetables.
Here are some things to know about the materials, whether you choose a kit or build your own bed from scratch:
■ Cedar: Cedar is a naturally long-lasting material that needs no added sprays to make it weatherproof – and it looks great in the garden, which is why most commonly available kits use cedar boards that will last for many seasons. Box store lumber departments and lumber merchants usually have cedar boards. The only decision to make when buying the lumber is how deep you want the bed. Standard boards come in 6, 8 or 10-inch widths and lumber departments have 8, 10 or 12-foot lengths. Most stores will cut the boards to 4 feet, which is a standard size for beds and fits easily into cars.
■ Redwood: Redwood has similar insect and moisture resistance as cedar and makes an excellent raised bed frame. The weathered redwood boards take on an attractive gray color that blends nicely into any landscape. Alas, redwood raised bed kits or boards are not always as easy to find as cedar.
■ Composite materials: These materials are similar to those used on decks. Composites are a blend of polymers and wood, giving a natural wood look and feel but with greater weather resistance. Kits made from composite material are found at many large stores, but you could have trouble finding boards to make your own beds.
Not all raised beds need wood – concrete blocks and bricks work well too.
■ Recycled plastic: Garden beds, edging and raised bed kits made from weather resistant recycled plastic are very common. Costs vary tremendously, though you do get lots of color options, from bright primary colors to more subtle cedar colors, redwood colors and browns. The materials are generally lightweight compared to cedar beds and are a great option for temporary beds.
■ Non-wood beds: There is no rule that a raised bed has to be made from wood-like boards – it can be constructed with breeze blocks, bricks and almost anything that can keep the soil inside from flowing out. Concrete blocks are economical to buy and very easy to assemble, and though not particularly attractive in the beginning, they are quite acceptable when filled with vegetables and flowers.
What size do you need? Raised beds can, of course, be of any size you like, but most commercial kits are for 4×4-foot beds. These can be placed one on top of the other to make deeper beds or extended to make an 8×4-foot bed. Depths vary from 4-6 inches in the smaller sets to a full 8 inches in larger sets. For the first year, a simple 4×4 is probably a good way to go. Buying the lumber and getting it cut to size is often cheaper than buying sets, unless you get last year’s kit on sale in late winter. If you opt for building the garden yourself, you can pick the depth that suits you. For root vegetables such as carrots and potatoes, 10 inches is the minimum depth for successful growth.
■ Width: A 4-foot width is the most common bed size because most people can reach about 2 feet inside a bed, so from either side, anything within that 4-foot bed can be tended to. The material inside a raised bed is very friable (light and easy for roots to penetrate) and loose and is quickly compacted when walked on, so tending the beds from the edge is an important consideration. And because the 4-foot width is standard, most added screens and hoops are made to fit a 4-foot frame. This does not mean that you can’t make the bed 3 feet or even 2 feet in width if that is better for your space.
■ Length: It is totally up to you. A 4-foot square is a good starting point, but if you really like row crops such as peas and beans, you could consider a longer bed, maybe 8 or even 10 feet. This is particularly useful when you want to rotate what grows in the garden next year (see page 58 for tips on crop rotation).
■ Corners and anchors: Kits come complete with corner anchors, screws and brackets, items that will need to be purchased if you plan to build the bed yourself. There are a few different ways to anchor the boards together, and some are easier than others.
A raised planter with adjustable wheels (with brakes) allows a gardener to stand or sit while tending to the plants.
Adaptive Gardening: Many people who find it difficult to stand or who are restricted to a wheelchair can still enjoy gardening – not only by using the edge of a raised bed as a seating platform, but by raising the whole garden bed on legs to achieve a comfortable height. Here’s how:
Using the same 4×4-foot design, construct a raised bed from wood as normal. Then fix a base to the bed and secure it. The base can be wood boards or a 4×4 sheet of sturdy wallboards. The boards should be weather resistant and able to not only support the weight of wet soil but allow drainage as well, so drill a few holes into a board to allow the water to drain easily. Finally, attach the legs on each corner at the correct height for the gardener who should be able to reach to about the middle of the bed. An alternate design is to make the depth of the whole garden bed about 2 feet and create a broader seating area around the perimeter (8-12 inches), so that a person with limited mobility can sit down comfortably and easily reach into the bed to tend the plants. See page 34 for a word about adaptive tools.
Fill that Raised Bed!
You have found a place for the raised bed in the sun and constructed the bed – and now it is time to fill the bed with healthy growing medium. Do not use regular garden soil taken from a nearby garden bed, as that soil is dense and filled with bacteria and contaminants. In fact, the clay or sand that you have in the garden is one of the reasons people resort to the raised bed in the first place, so nothing is achieved by filling the bed with that soil. A preferred mix is a combination of compost plus aerators. Garden centers carry a variety of suitable growing mediums. Composts from cows or mushrooms sit alongside container mixes and organic mixes. Readymade mixes come complete with a light texture and frequently a fertilizer too. For vegetables, it is best to look for a mix that either has an organic label or does not include urea fertilizer.
A perfect mix can be made right next to the raised bed and includes material from a variety of bags, each containing a slightly different set of nutrients.
Compost should be the dominant part of your mix and this can be from single or multiple sources. Next, you’ll add some perlite. Perlite is a volcanic material that helps to lighten the soil, aerate and increase drainage to the overall mix. Finally, add peat moss. The overall mix should end up being about 50% compost, 30% peat moss and 20% perlite. These do not have to be exact, but follow this general guide.
For a single raised bed, empty a
