Raised beds have become a very popular way to grow vegetables, flowers and herbs in the garden. The advantages are many. Raised beds heat up the soil and drain it faster so you can plant sooner in spring. Raised beds contain fertile soil so you can plant closer together. Raised beds don't compact the soil because you're never stepping on the beds. Raised beds have less weeds and are easier to care for and to water. Raised beds identify where the paths and garden beds are so they're less likely to get trampled by pets and kids.
There are two main types of raised beds; free standing and structured. Free standing raised beds are built each spring and slowly flatten out over the summer. Structured raised beds are more popular and can be made from a variety of materials such as wood, stone, concrete blocks, metal and composite woods.
Not all raised beds are created the same. There are advantages and disadvantages of each type. So, let's take a look.
Wooden Bed
Wooden beds are the most common raised bed. First, choose rot resistant types of wood such as cedar and redwood to build the bed. Avoid chemically treated woods. They will last longer than soft woods such as pine. Select 2-inch diameter pieces of wood that are not more than 8 feet long. Make the bed no more than 4 feet wide. Select wood that is at least 10-inches tall. You can stack the wood as high as 3-feet tall for elevated raised beds. These are good for reducing bending and keeping weeds and small animals out of the bed. If mice or voles are a problem in your bed, line the bottom with hardware cloth and make a taller bed. For 8 foot long raised beds place a wooden brace half way down to prevent bowing. Use metal raised bed corners or reinforce the corners with 4-inch diameter posts to keep the bed square. Wooden beds are attractive and functional, but do eventually rot and need to be replaced. Consider using recycled wooden composite beds that are longer lasting and more environmentally friendly.
Stone Beds
Field or flat stone make excellent raised beds. They are long lasting and durable. However, once established you won't want to move them soon. Like the wooden bed, aim for a 10-to-12 inch tall, or higher, bed no wider than 4 feet. The stone can be free standing or held together with mortar. Some unique stone planting beds feature a 3- to 4-foot tall wall with a space in the center for soil and plants. This creates a planting space that's protected from animals and warms up quickly in spring. My mother had a planting bed like that made from brick. Other similar materials such as concrete blocks, bricks and pavers can be used. In a small bed, remember concrete materials can leach lime into the soil and raise the pH.
Metal Beds
A third type of raised bed material is metal. This has become very chic, especially in urban areas. Corrugated aluminum and sheet metal are used to fashion square, curved or rectangular beds. Many metal beds have size measurements similar to wooden beds, but often some are 2- to 3-feet tall. The advantage of metal beds if the material is long lasting and the soil heats up quickly in spring and stays warmer in fall. The downside is the soil warms up fast and can get really hot in summer. This can be a problem for cool soil-loving plants such as spinach, peas, and greens. Big metal beds have enough soil volume to absorb the heat, but smaller beds may get too hot. The solution is to grow heat loving plants in these beds such as portulaca, succulents, melons and sweet potatoes.
Soil Considerations
Whatever type of raised bed you construct or purchase this spring, remember to fill it with a 50:50 mix of compost and topsoil. If the soil still seems heavy, you can add potting soil as well. This should make for a fertile, well drained mix all summer. In elevated wooden raised beds, consider creating a false bottom, 1 foot down from the top made from marine grade plywood. Poke holes in the plywood for drainage and place window screen over the holes to prevent the soil from draining out. There will be enough soil to grow most annual vegetables, flowers and herbs. You'll reduce the weight of the bed and the amount of soil needed to fill it. Plus, critters, like voles, won't tunnel up through your bed to feed.
Until next time I'll be seeing you in the garden.
Charlie Nardozzi is an award winning, nationally recognized garden writer, speaker, radio, and television personality. He has worked for more than 30 years bringing expert gardening information to home gardeners through radio, television, talks, tours, on-line, and the printed page. Charlie delights in making gardening information simple, easy, fun and accessible to everyone. He's the author of 6 books, has three radio shows in New England and a TV show. He leads Garden Tours around the world and consults with organizations and companies about gardening programs. See more about him at Gardening With Charlie.
