Vegetable and herb gardening in North Texas soil provides more challenges than many gardeners want to face. Soil may have so much clay that it is like digging in concrete when dry. Alternatively, clay soils hold moisture too long overwhelming plant roots after sustained rains. Many North Texan’s native soil is alkaline, with pH values above 8.0. The high pH keeps some nutrients, such as iron, manganese, boron, copper and zinc, unavailable to growing plants. Using raised bed gardening techniques solves many problems challenging would-be vegetable growers.
- Provides easy-to-dig, nutrient-rich soil selected for gardening
- Allows control of pH and fertilizer tailored to a plant’s requirements
- Offers better drainage
- Warms more quickly in spring
- Reduces soil compaction because you walk around, not in, a raised bed garden
- Provides more space for plants since you do not need paths between rows
Building a Raised Bed
Raised beds are freestanding garden beds constructed above the natural terrain. A raised bed does not have to be very deep to be effective. Eight to 12 inches is usually adequate. If drainage is a problem, or if the plants you are growing prefer drier soil, the bed could be taller and filled with a porous growing medium. Vegetable beds should be 12 to 18 inches deep. The material used to edge a raised bed should be stable, durable and attractive suggests Texas AgriLife Extension Service. Wood planks, brick and mortar, landscape timbers or concrete blocks may be used to surround the raised bed and contain the soil. Select a level location with full sun for growing summer vegetables. Cold weather vegetables and some herbs tolerate a small amount of shade.
Here are a couple examples from Raised-Bed Gardening by the University of Missouri, Department of Horticulture:
Raised bed garden made with wood
Raised bed constructed using concrete blocks
Raised Bed Gardening at the DiG
At the DiG, the team used both concrete blocks and wood for our raised beds. The wood beds were built with treated lumber. Cedar was the wood of choice. The beds were a foot deep and filled with Dyno Dirt.
The DiG team installed drip irrigation controlled with timers in the raised beds, except the vegetable garden, which used soaker hoses. You can find more information at “Drip Irrigation: A Smart Way to Water.” A drip system or soaker hose uses less water than overhead sprinklers and allows the water to get to the plant roots without wetting the leaves, which can lead to moisture-based fungal infections.
During the summer, the DiG battled Bermuda grass in all of our beds. Bermuda grass is doubly challenging to control because it spreads via seeds and runners. Bermuda roots run deep and removing every little bit is difficult. When we re-do the beds, we will use professional landscape cloth at the bottom of the bed after treating the area with glyphosate — a broad-spectrum systemic herbicide. Some beds may be deepened to 18 inches. Even with treatment, a good preventive measure is to clear 3-inches around the beds of weeds and grasses.