By Miguel Rios. Ever had trouble growing vegetables or struggled with plants not reaching their true potential? You may have labored to achieve perfect watering schedules, only to find your plants still failed to thrive. Welcome to the world of soil pH. Soil typically needs to be at a neutral pH level to provide essential nutrients for plants like vegetables.
Our dry climate and calcareous limestone soils tend to be alkaline, making it less ideal for plants that prefer acidic pH levels. Most of the recommended Texas native and well-adapted plants will probably perform well in alkaline soils. But plants that prefer acidic conditions — like gardenias, azaleas and many pine trees — will often struggle.
What is pH?
pH is the measure of alkaline and acidity levels in the soil. The acidity and alkaline levels are based on the concentration of hydrogen ion elements in your soil. (Hence the abbreviation pH, for the Potential of Hydrogen.) Hydrogen is a major building block in the plant cycle, in which the plant transports and process nutrients.
The concentration of hydrogen ion levels is measured by a scale of zero to 14.
- A pH less than seven is considered acidic, meaning a lack of hydrogen.
- A pH level greater than seven is considered alkaline with more hydrogen.
- A pH level of seven is neutral. (Most vegetable plants grow with a pH level of six or seven.)
When the pH level is too low or high for a particular plant species, the absorption of nutrients can “stall” and nothing will be available for the roots absorb.
How to test your soil
There are different ways to test your soil, the easiest being with a pH test strip that changes colors according to the pH level. Test strips can be found at your local garden or pool store. Gather a soil sample 6 inches deep into a cup and mix ½ cup of deionized water into the soil sample. Dip a pH test into the mix sample and wait about 5 minutes for the color results
How to adjust the soil pH level
It’s possible to amend your soil to adjust the pH, especially for growing vegetables. Dolomitic lime or wood ash can raise pH by neutralizing acids; sulfur or peat moss can lower it by neutralizing alkaline soil. Any additional elements should be watered down before any planting. (Remember, chemical amendments can be hazardous, so follow the directions and wear gloves and a mask.) Adding organic compost can help maintain the neutrality of the soil over time.
Miguel Rios is known to be a jack of all trades, not only as a licensed irrigator and SAWS field investigator, but he also holds a degree in biochemistry from The University of the Incarnate Word. Miguel plans to further his education in botany and biochar to start his own fruit and vegetable harvest. When he’s out of the office as a field investigator, he enjoys the outdoors, including hunting in West Texas, camping with his family off the Guadalupe River, planting and barbecuing.