Home > Plant Talk > Test the soil for a happy new year in your yard

Test the soil for a happy new year in your yard

 feed icon
Thursday, January 4, 2007
One of the most common questions I'm asked by new Master Gardener students has to do with improving the health and vigor of landscape plants.

One of my new students said, "Sometimes I just want to give up on my yard. No matter what I do, the lawn looks horrible and the shrubs and flowers seem to struggle along."

After asking her for a few more details, it was obvious that she had neglected to do some very basic yet essential tasks, such as soil testing. It turned out that the rhododendrons and azaleas in her shade garden were yellowing and deficient in nutrients because the soil pH was too high.

Although she was adding fertilizers, the soil acidity was not adjusted properly, so these acid-loving plants could not efficiently absorb nutrients from the soil.

Her lawn was struggling due to soil drainage and compaction problems as well as lack of adequate sunlight. As this student and others in the class progress through their training, they learn about some key factors needed to prepare beds before planting.

The first step is to gather some information about the soil in your yard. I recommend testing the soil in your yard and garden to determine soil acidity or pH as well as nutrient levels. Take a separate soil sample for each area of your yard -- where the type of plants differ, management differs or the soil itself differs.

In my yard, for example, I would gather a separate sample for the vegetable garden, one for the front lawn area, one for the back lawn, one for the flower beds and one for the shrub bed on the side of the house. For each area, I would take 10 to 15 random samples by getting a thin slice of the top 6 to 8 inches of soil. Mix each sample completely in a clean bucket and make certain the sample is dry before placing in the soil sample bag. You can dry samples out by spreading out on a clean surface and leave out in the sun until dry. Only one pint of soil is needed to send off to a soil testing lab. Soil testing can be done at any time of the year, but fall or early spring may be best to allow time to get results back from the lab and make any necessary soil amendments.

Soil test results from a reputable soil testing lab will provide valuable information about the soil's pH (acidity) and nutrient levels. The lab will match the results with the type of plants you have in each test area. So, it's very important to mark each sample clearly and to completely fill out the forms for each sample.

If soil pH is not adjusted properly, plants can suffer from nutrient deficiencies, even if you are adding fertilizers. Plants differ in their pH requirements and what's good for one plant may not be good for another. The pH range runs from 0 or pure acid to 14 which is pure alkaline. A slightly acid pH of 6.5 is ideal for many plants including lawns, and many ornamentals and vegetables.

Plants such as rhododendrons and azaleas thrive in a pH range of 4 to 5.5. Cabbage is grown in a slightly alkaline soil of pH 7.5 to help prevent clubroot fungus. So it is important to first determine soil pH before planting and to properly adjust the soil pH to match the specific needs of each plant. Plants can then be grouped in the landscape according to their pH needs to help simplify management.

If you want to improve your chances of success with plants in your yard, make a New Year's resolution to test your soil in the early spring. In future articles, I will discuss soil drainage problems and how to improve poor soils to provide an ideal environment for plant roots.


Bill Hlubik is a Professor and Agricultural and Resource Management Agent for Rutgers Cooperative Extension- The New Jersey Agricultural Experiment Station, Rutgers University. He is also a host of the "If Plants Could Talk" television series (www.ifplantscouldtalk.rutgers.edu on NJN Public Television.