Gardening in raised beds is one of the best ways to grow productive and healthy plants. They allow for better control of drainage, the opportunity to create custom soil, a defined planting area and a more user-friendly work area. Although raised beds can be as simple as mounding up soil into a deep wide planting area, you can also have a physical border around your garden.
What Materials Should Be Used?
Anything material that retains the soil will work, from scrap concrete to lumber to railroad ties. Even composite wood is becoming more popular. Non-treated, rot-resistant lumber such as cedar works best. Pressure-treated wood is less expensive, but there is some debate around the safety of its use, especially if using the beds for edibles.
How Tall Should it Be?
Beds that are 12 inches tall have more success than shorter beds. This gives plant roots a great environment for expansion and growth. However, a six-inch bed height is adequate if your soil is well amended. You can also build raised beds waist high to minimize bending over. As long as the soil is well amended, anything over six inches will do.
How Long and How Wide?
Length is optional and limited primarily to your physical space. Width, on the other hand, is more important. Beds should be wide enough to allow for at least two rows of plants. Three rows is fine as long as you don't make the bed so wide that you can't reach into the center. Plants grow well in beds at least 12 feet long and three feet wide. However, a bed that is four feet wide provides even more planting options.
If you are using flexible material such as lumber, the pressure of the soil will cause the wood to bow out. Provide staking halfway down the length and secure the wood to it to prevent this outward bowing.
If using wood, build the frame so the wood grain on all boards is facing inward. Otherwise, they may pull away and curve toward the outside as the wood dries and weathers. Not only is this unsightly, but it can also pull the screws or nails out as well, making your beds less secure.
Use galvanized 3-inch screws instead of nails to secure the wood. Screws are forgiving than nails if you make a mistake. To prevent splitting, drill pilot holes first toward the ends of each piece.
Premade kits include connecting joints and hinges to configure your bed shape and height the way you want. These devices make bed setup a snap without any construction.