Some garden herbs will prefer acid soils while other herbs prefer a soil that is more alkaline. Soils in moist climates tend to be acid and those in dry climates are alkaline.
A simple explanation of soil ph: The pH of your herb garden soil is the measure of soil acidity and is an important test to assist you in maintaining calcium levels and other trace elements in your herb garden.
A soil pH level above 7.1 is becoming alkaline.
A soil pH level of 7.0 is considered neutral.
Garden soil ph level which tests below 6.0 is becoming acid.
A typical soil pH level of 6.0 to 7.0 is enjoyed by most herbs although some herb plants can be sensitive to other soil pH levels.
The best way to quickly judge the pH of your soil is by the physical appearance of the herbs which are growing in it. If your herb garden doesn't appear to be doing well or if your garden space is new, then consider soil testing to determine the soil pH.
Many garden centers will test the pH of a herb garden soil sample for you, or you can buy an inexpensive pH test kit at an online garden supply or local nursery. The test kits generally consist of a test tube, some testing solution and a color chart to help you gauge the soil pH and other soil nutrients such as nitrogen, phosphate and phosphorus.
Simply put a pre measured sample of your soil in the test tube that comes with the soil test kit, add a few drops of test solution, shake it up and let it settle for a few minutes. The solution in the tube changes color according to the pH of your soil. Compare the color of the sample with the color chart that came with the kit. Matching colors will tell you the pH of your sample. Quality pH test kits will have a chart to help interpret the test result.
A Soil pH Tester (meter) is another way to do a quick pH test on your own. These devices typically have an attached probe connected by wire to the control box which houses a meter with and indicator needle. By placing the probe into moistened soil the indicator needle gives an indication of the soil pH at the point where the soil meets the probe.
Once you have determined the soil pH you can easily make needed adjustments to the soil. Inexpensive materials to adjust your soil pH levels are readily available through local garden suppliers or online merchants.
To increase your pH by 1.0 point and make your soil more alkaline:
One of the best and least expensive was to lower garden soil pH is to add peat moss, available at most garden centers. Follow the directions printed in the back on the bale. If available, composted leaves, wood chips, leaf mold will also do a nice job.
Another way is to reduce the soil pH by 1.0 point is by using ground rock sulfur. The sulfur should be thoroughly mixed into the soil before planting.
Adding the required materials to adjust soil pH is not a quick fix. The soil should be periodically retested to ensure the steps which you have taken are having the desired affect. It can take many months to register a change in the pH of your herb garden soil.
There are websites available to help you determine how much lime or sulfur to add to adjust the the soil pH of a given garden size. Try the Herb Garden Lime or Sulfur Calculator of the National Gardening Association.Herb Garden Lime or Sulfur Calculator
It would be unwise to attempt to make any adjustments to your garden soil pH without soil testing. Over correcting may cause damage to herb crops. It is easier to soil test your herb garden each year and make adjustments gradually. Lime or other products which change the soil pH should be applied only when tests show it to be necessary. They are always best applied in the fall, or as early in the spring as possible. Correction of an overly acid or alkaline soil should be considered a long term project. It should always take several gardening seasons to correct your herb garden soil pH.