Why soil tests are important
I often get questions from friends and neighbors about plants that are not doing well. These folks get exasperated when I tell them that they need a soil test, because that’s not what they want to hear. But soil testing is extremely important if you want to get the best results from your plants. My garden does fairly well, yet I still take many soil samples each year. Testing is easy, and free in North Carolina. Here’s how.
Different plants require different soil conditions, so take separate samples for each type of plant, and for the same plant in different places. I have 10 vegetable beds, and sample each one separately. Similarly, 4 lawn areas, 20 shrub groupings, 4 slopes with ground cover, and 8 flower beds are tested individually. The vegetable and flower beds are sampled each year. Shrub beds and lawn areas are tested every 3 years. Places where previous tests have shown a problem (like high pH in the blueberry patch) are sampled each year until the problem has been corrected.
The accuracy of the test depends on the quality of the sample. Use stainless steel, chrome plated, or plastic tools. (Brass, bronze, or galvanized steel tools may contaminate the sample.) The soil should be slightly damp to dry (not wet). Get several scoops of soil from different places in the area you are sampling, and mix them well in a clean plastic bucket. Fill the sample box, and dump any excess soil. Clean the tools and bucket, then sample the next area.
Complete a Soil Sample Information form for each sample. Create a unique ID for each sample so that you remember where it was taken.
Forms and sample boxes are free at the Haywood County Extension Center at 589 Raccoon Road in Waynesville. Indicate on the form the type of plant you will be growing in each area sampled. Ship the samples to the address on the form.
The test report will show the relative acidity of the soil (pH), and if the pH is too low, how much lime to add. This is extremely important, because if the pH is different than what the plant likes, nutrients in the soil will not be absorbed by plant roots even if the soil is fertile. Growth will be slowed, and the plant will be more likely to have disease and insect problems. Download a list of optimum pH values for specific plants at
The test report will also show the level of several essential nutrients. If a nutrient deficiency exists, the report will tell you how to correct it.
These reports contain a lot of information and can be confusing. If you have questions, call the Extension Center at 828-456-3575. They can access your test results on the internet and explain what you need to do for the plants you want to grow.
Early fall is an excellent time to send in soil samples, because the turnaround time is much shorter than in the spring when everyone is getting ready to plant.
Send in soil samples from each area of your landscape on a regular basis, and your garden will be much better as a result. For more information check out “A Gardener’s Guide to Soil Testing”, NC State Publication No. AG-614 at http://www.cals.ncsu.edu/agcomm/publications/Ag-614.pdf.
Jim Janke is an Extension Master Gardener Volunteer in Haywood County. © 2012 NC State University.