Raised bed gardens

 

 

 

February 12, 2004
DIANE SMITH
Victoria County
Master Gardener

If poor-quality compacted soil, a drainage problem or a physical disability is preventing you from gardening, then garden beds raised several or more inches above the natural terrain may be your answer.

Raised bed gardens have several advantages over standard gardens. Plants that may not naturally thrive in your garden may grow into lush, healthier, more productive plants when grown in raised beds. Few grasses, weeds and tree roots interfere with raised gardens. The soil even warms up earlier in the spring allowing for earlier planting. The physically challenged may prefer to raise the garden bed to chair height or waist high by constructing tall legs on the structure. This will enable the person to work completely around the garden while not having to bend or leave his or her chair. Once the construction of the bed is completed and it is filled with amended soil or rich compost, the garden nearly cares for itself with the exception of watering and occasional weeding.

The first step in planning a raised bed is deciding on its location and size. I have a garden home where space is limited - and so is the sun. Site selection and plant selection go hand in hand. So select your site based upon the right location for the appropriate amount of sun needed by your plants. While many vegetables and herbs need full sun, many prefer morning sun as opposed to that of the scorching summer afternoon. Another factor in location choice is drainage. Good drainage ang proper air circulation are vital to healthy plants. If the bed contains clay soil, it should be amended with sand, organic matter or a coarse grade of perlite to improve drainage. Consider using a rich compost such as pecan or mushroom compost, which incorporates organic material needed for healthy plants.

Selection of the bed materials is the next step. The location of the bed, its size, and the type of plants will determine the style and materials used in the bed construction. My bed is not readily seen from my patio area, so I chose treated lumber, 2 inches thick by 12 inches wide by 8 feet long. The new non-arsenic lumbers are recommended - alkaline copper quaternary or ACQ, copper boron azole (CBA) and Tanalith E. They replace the old CCA arsenic treated lumber phased out by EPA as of December 2003 for anything with which children might come in contact.

I then marked off the area using my lumber as a guide and sprayed the area with an herbicide such as Roundup or Grass-B-Gone, diluted according to directions to kill the Bermuda grass and weeds that had taken over the area. This step was very important, and I was patient because I knew it would help deter the constant battle of unwanted grass and weeds in my garden. What building materials you choose will be determined by the shape, size and purpose of the garden. It may be elaborate, visually esthetic or very functional. Landscape timbers, telephone poles, railroad ties, concrete blocks, rocks or metal edging may also be used.

Construction on the two 4 feet by 8 feet raised beds began when my father drove from Rockport with the materials loaded on his truck. He pre-drilled and pre-cut some of the lumber in his workshop from the plan we had designed, and this made the construction easier. This became a wonderful father-daughter project that was completed over a weekend and will be enjoyed for years to come.

Once construction was complete, I lined the bottom with a weed mat material. Old carpet also works well to prevent the re-growth of weeds and grass. Choosing the correct soil and its additives are very important. A good quality loam mixed with compost and manure is an excellent choice. To conserve watering, I arranged soaker hoses on the beds. I find it easier to plant around the hoses instead of placing the hoses around the seedlings and plants.

At last, the fun part begins - designing and planting. Since the area is small, drawing out a planting guide is recommended. I use one of the raised areas primarily for herbs such as dill, parsley, cilantro, thyme, lavender, chives, lemon balm, basil, oregano and salad burnet. During the summer the other bed is planted with tomatoes (Merced), assorted peppers, green beans (pole), eggplant (Japanese long slender purple or green) and okra. For the fall planting try sugar snaps, Swiss chard, leaf lettuces (Romaine, red sails, oak leaf and butter crunch varieties), carrots, Brussels sprouts and spinach.

Trellises are terrific space savers in your raised beds. I prefer to build trellises and tomato cages from bamboo and wooden slats, but other good materials are PVC, wire and wood. Many garden stores have great selections of freestanding iron trellises and topiary forms. Even a fold-up laundry drying rack makes an interesting trellis. Consider decorating a nearby fence with birdhouses and garden plaques. Be creative with the use of personalized stepping stones embedded with shells, marbles, leaf imprints, broken tile and pottery, or even your name.

Mulching with straw, hay, shredded leaves or ground bark helps retain and conserve moisture. Don't forget to add organic material every season and have your soil tested every two or three years to determine what nutrients may be missing. Information about soil testing is available by calling the Victoria County Extension Office at 361-575-4581. Visit the Victoria Educational Gardens (VEG) located near the Victoria County Regional Airport to see numerous raised gardens constructed of various materials.

The Postage Stamp Kitchen Garden Book is a delightful source to use as a design and planting guide in small spaces. Some themes for raised gardens might be salad, Italian kitchen, Oriental, Mexican, French, teas, edible flowers or cut flowers.

Notice the illustration of the construction project for the raised bed that is currently in my yard. Following the illustration is a list of supplies and directions for constructing one 4 feet by 8 feet bed. The best part is enjoying the finished product, and you will never have to till again. Gardening has never been simpler. No more aching back. See you in the garden.

*Three 2x12 8-footers (Cut one in half for end pieces)

*One 4x4 8-footer (Cut into four equal pieces, approximately 2 feet long to be used for corner reinforcements)

*Two 2x4 2-footers for side reinforcements

*Twelve 3/8x6 galvanized bolts with nuts

*Four 3/8x5 galvanized bolts with nuts

*Thirty-two 3/8-inch flat galvanized washers

Drill two 3/8-inch holes in each end of the 2x12s and through the 2-foot long pieces of 4x4s for reinforcement.  Bolt together with 6-inch bolts and washers.  One foot of each 4x4 reinforcement posts will protrude into the earth for stability.

Bolt the 2-foot pieces of 2x4s midpoint of the 2x12s with 5-inch bolts and washers so 1 foot of each will protrude into the earth to keep the sides stable.

Dig six holes in the earth to accommodate the 1-foot long reinforcements.

The 2x12 8-foot frame will sit on the earth ready to be filled with soil, sand and organic material.


For further reading on Raised Bed Gardening consult any of the following:

Murphy, W.B., J Pavia and J. Pavia. 19910, "Beds and Borders: Traditional and Original Garden Designs." Houghton Mifflin Co., Boston, Mass.

Newcomb, Duane and Karen. "The Postage Stamp Kitchen Garden Book." Adams Media Corp., Holbrook, Mass.

Sperry, N. 1991. "Neil Sperry's Guide to Complete Texas Gardening." Taylor Publishing, Dallas, Texas. Page 38.

Wasowski S. and A. Wasowski. 11997. "Native Texas Gardens: Maximum Beauty, Minimum Upkeep." Gulf Publishing Co., Houston, Texas.

Texas A&M University System Extension Publications on the Web at: http://tcebookstore.org/     http://www.diynet.com/diy/fv_planting_harvesting/article/0,2029,DIY_13828_2269848,00.html