Are your plants struggling? Before you do anything else, check your soil pH. Soil pH is the measure of the acidity (sourness) or alkalinity (sweetness) of a soil. The pH scale goes from 0.0 to 14.0, with 0.0 being most acid, and 14.0 being most alkaline. The value 7.0 is neutral. Soil pH plays a critical role in the absorption and utilization of essential trace elements required for healthy plant growth.
Few plants will grow if your pH is either too low or too high. Most plants favor a mildly acidic growing environment of around 5.8 to 6.2. Ornamental plants prefer a slightly more acid environment of 5.2 – 6.5, while vegetable crops prefer a pH range of 6.0-6.5. Some of our garden favorites however are acid loving plants including Azaleas, Gardenias, Camellias, Blueberries and Blue Hydrangeas which prefer a pH of 5-6.5. When choosing plants for your garden it is wise to group them by their preferred needs for pH, light intensity and desired pH. By doing this you will be able to enjoy a wide range of plants while giving them ideal conditions for optimum health and performance.
The chart shows how pH will determine whether soil nutrients are more or less available to the plants. If the pH is out of the required range, essential elements will become unavailable to the plant, resulting in slow growth rates and poor yields due to nutrient deficiencies.
Fortunately you need not be a scientist to determine your soil pH. You can simply purchase an inexpensive three function device that will measure Moisture, Light and pH. These devices have two probes, just stick them into the soil (soil must be moist for pH measurement) and it will do a fairly accurate reading of your pH. Adjust the meter’s switch to the moisture mode and it is a moisture meter that you can use to make sure you are not overwatering your house plants. The final mode gives you an indication of the light levels in your garden or home. Every gardener should have one if you want to be more successful. These devices can be found at your local garden center, big box stores and on-line. They do not require batteries to operate so they are always ready to use.
For more accurate results and specific guidance on how to adjust your soil pH and what kind of fertilizer you may need, a soil test is the answer. You can pick up a soil test kit with instructions from the Shelby County Extension office (located at the Agricenter). Mail in your sample with your payment and you will get the information you need to become a gardening savant.
To adjust your soil pH, three things are needed. Lime is used to increase the soil pH. Elemental sulphur or aluminum sulfate lowers the soil pH. The third factor is time, as the process to adjust soil pH is slow, it can take as long as a year before you will see the results. Neither lime nor sulphur are water soluble so working the material into the top six inches of soil will speed the process in new beds but top dressing is recommended for established beds to prevent root damage.
Because there are ongoing factors that can impact your soil pH you will want to recheck your pH every 3-5 years. Wet climates have a greater potential for acidic soils. In time, excessive rainfall leaches the basic elements (calcium, magnesium, sodium, and potassium) that prevent soil acidity. The Memphis area receives 54.7 inches of rain a year; anything above 35 inches in the U.S. is considered a wet climate, so we are prone to acidic soil. Heavy use of nitrogen fertilizers will also drive up pH over time. If you love a lush green lawn and apply fertilizer several times a year you may need to lime your lawn more frequently. However, never assume, and be sure to check the pH first to make sure it is necessary, as too high a pH will create problems you don’t need.