Rio Grande Valley residents, whether native, immigrant, or wintering only, all understand that this geographical area comprises a physical environment with challenges unlike any other. Many farmers as well as home gardeners have known the exasperation of watching trees, shrubs, flowers or vegetables they have planted fail to thrive, even when their care seems to be just right, and sometimes, even when the same variety is doing quite well just feet away from the failure.
A number of factors may be contributing to these mysteries of success and failure. Have patience and take the time to observe, understand and learn from your experience. Additionally, take time to become familiar with what the general growing conditions of the Rio Grande Valley are.
The USDA maintains a map of hardiness zones that divides Canada, the United States, and Mexico into 11 zones based on average minimum temperatures. The Valley is considered to be in Zone 9b. However, the map is currently being revised, and the new one will put us in Zone 10a. Keep in mind that the map is based on temperature variation over a span of many years and in any given year we may functionally be in one zone or the other due to the severity of one winter.
The wind is a part of our landscape and must be recognized as a major stress factor. Wind over 15 miles per hour causes turbulence and temperature changes that affect the health of plants, with the effect varying depending on the plants’ level of exposure. Windbreaks are crucial protective elements in any landscape.
The Rio Grande Valley is actually a delta of the Rio Grande River. This delta contains many soil types, from sandy to clay, but it is generally always alkaline, with an average pH in the range of 7.6 to 8. Soil salinity is usually high.
Given these characteristics, it is wise to begin at the beginning when planning a garden or landscaping. Get your soil tested so that you know what you have. Dig test holes a couple of feet deep and take samples from different areas of your property. Many homes are built on soil or sand brought in by builders, and may not even be sitting on native topsoil. Find out what your soil lacks and learn what you need to do to add it back in.
Enrich the soil with organic matter, thereby enhancing the fertility of the plants that will make their home in it. Work compost into it; whether home made or purchased it will improve the quality and quantity of nutrients available to your plants. A layer of mulch on top will lower the soil temperature, and add nutrients as the mulch breaks down. Nutrients in soil are continually being used up by what lives in the soil and need to be replenished.
