The life of a plant can be a difficult one. From the time it germinates from a seed or is propagated from a cutting, a plant is expected to delight, amaze and even inspire its human caretakers. And if it fails or ceases to draw an occasional gasp or smile of appreciation? Another eager plant is waiting nearby to take its place.
Too often, the reason a plant does not perform to our satisfaction has nothing to do with the plant itself and everything to do with us and the surrounding environment. But unfortunately, the plant pays the ultimate price.
It is difficult to meet a Florida gardener who has never complained about the poor quality soils we encounter in this state. Yes, believe it or not, sand is a type of soil. But in dealing with poor soils in our landscapes, we must address drainage issues, nematodes and other pests, nutrient availability, soil pH levels, weeds, erosion… The list goes on and on.
Rather than continue to fight with the existing soil at ground level, consider an alternative: raised bed gardening. There are several benefits to gardening in raised beds. For one, you have better control over the quality of the soil in which to plant. Soil borne problems like nematodes can be controlled more easily. Access to plants for pruning, harvesting and weeding is easier because the plants are above ground level. Finally, raised beds, if designed as such, can serve as decorative hardscapes in your yard.
The first and most important consideration when building a raised bed is the material used. Avoid treated wood, since there may be a risk of chemicals leaching into the soil and nearby plants. Many types of construction materials, including bricks, stones and plastic, may be used. Your choice of material will depend on your style and budget.
When considering a location for your raised bed, look for a level spot that receives at least 4 to 6 hours of sunlight. Using a hose or string, lay out the approximate size and shape of the bed. Don’t make it too big; you will need to reach the plants in the middle of the bed as well as along the edge. If building multiple beds near each other, be sure to leave enough space in-between so that you can walk and work around them. Use a pervious material like gravel or mulch to line the walkways between and around the raised beds. If you build a shallow bed (6 inches or less), consider lining the bottom and edges with weed cloth to keep grass and weeds from creeping into the bed.
A raised bed should drain well because soil that remains very wet will deprive plant roots of oxygen. This is especially true for vegetable beds. The best type of soil for your ornamental raised bed is sandy clay loam soil mixed with organic matter like peat moss, finished compost, sawdust or ground bark. For vegetables, the best mix is one-third topsoil, one-third peat moss, and one-third sand or perlite. When you add soil to your raised bed, be sure to grade the soil so that it slopes towards the edge of the bed, rather than the center.
Choosing plants for your raised bed garden is essentially the same as with a regular garden bed. However, if the raised bed is very shallow – 4 to 6 inches deep – you may be limited to planting annuals, vegetables and some herbs. The deeper the bed, the more plant options you have.
As always, the Florida-friendly landscaping™ principle of choosing the right plant for the right place holds true. For each garden bed, choose plants that have similar needs regarding sunlight, water, nutrients, soil pH and drainage. Also be sure that the mature size of the plants chosen is suitable for the location in the landscape. Woody perennials and shrubs should be placed at the rear or the center of the bed, depending on its position in the landscape, while annuals and groundcovers should be easy to reach for maintenance and replacement.
Once your raised bed is constructed and plants are installed, mulch the surface 2 to 3 inches deep to help regulate soil temperature, reduce water evaporation from the soil, control erosion and reduce weeds. Water the bed when needed, and check the soil in-between watering. If the top inch or two is still wet, there is no need to irrigate.
If designed, built and maintained correctly, a raised bed garden offers a host of benefits and options to any gardener. By choosing the right plants for your raised bed, you will be pleasantly surprised at how well they perform. For more information on building a raised bed garden, visit the Texas A&M Extension publication online at http://aggie-horticulture.tamu.edu/publications/guides/E-560_raised_bed_garden.pdf.