Getting Ready to Garden? Get Your Soil Tested First

This free service through the Department of Agriculture can save you time and money on your yard
by Joel Haas

All gardeners and farmers fight insects, weeds, blights, weather, and economics — but sometimes, the battle is lost before seeds are even planted. If your soil is too acidic or poor in nutrients, the growing conditions won’t be there, no matter what you do. Fortunately, here in Raleigh there’s an easy way to find out the profile of your soil through a program of the North Carolina Department of Agriculture and Consumer Services. 

Through funding from a tax on commercial fertilizer, North Carolina residents can mail or deliver a box of soil to the Soil Testing Lab at the Agronomic Services Division of the NCDA&CS in Raleigh to learn what makes up their soil.. The service is available year-round, and it’s free from April through the end of September, when it bumps up to $4  per sample. (That’s because after the fall crop harvest, the lab’s busiest season starts, as major farming operations send in samples to prepare for the following year’s planting. The fee covers extra employees to keep up with demand.)

How does soil testing work?

At the Soil Testing Lab, 16 full-time staff and a number of part-time employees, including some N.C. State University students, work to meet demand and keep turn-around time as low as possible. Dr. David Hardy is the head of the lab —  and he has more “dirt” on North Carolina than the SBI and FBI combined, since more than 300,000 half-pound sample boxes of soil pass through his lab each year. 

“Our soils testing program stands out as one of the largest in the country. I estimate we receive about 80% of our sample requests from areas east of Raleigh,” Hardy says. “Another 15% come from the Piedmont area, and the remaining 5% from the Western counties. Farmers send in samples for every 4 to 8 acres, digging up four to six inches of soil for each sample.” And while much has been made of all the high-tech companies moving to North Carolina, Hardy points out that agriculture and agribusiness are still the state’s leading industry, generating $95.9 billion yearly. 

Why should you get your soil tested?  

And while the service is primarily for commercial applications,  Dr. Jeana Myers, a horticulture specialist for the Wake County agricultural extension service, says that having a soil analysis of your garden can save you time and money. “Urban and suburban gardeners tend to overuse phosphates, which can quickly migrate to stormwater systems and from there into streams and rivers,” Myers says. “Plus, too much lime and phosphate can actually inhibit some plants’ ability to absorb nutrients.” A soil analysis can tell you exactly what you’re working with, so you know just how much fertilizer and lime to add — or not. Armed with knowledge about your soil, the Wake County Extension Services offers an extensive gardening guide that’ll detail your next steps. 

How to get your soil tested for free in Raleigh

To have a soil analysis done on your garden, you’ll need to go by the Wake County Extension Office (4001-E Carya Drive; it’s the first left east of I- 440 on Poole Rd) or to the NC Soils Lab (4300 Reedy Creek Road; go to the loading dock) to pick up sample boxes and forms. Once you’ve got your supplies, a clean stainless steel or chrome plated garden trowel and plastic bucket are all you need to provide adequate samples. (Though make sure both the trowel and bucket are totally clean — even minute amounts of copper, galvanized zinc, or other metals can throw the test results off). Clear the surface of the dirt you want to sample, then dig as deep as you’re planning to plant anything. Take a few scoops of soil from around the sides once you’ve made the hole. Don’t take a sample if the ground is too wet and make sure to remove as many roots and bits of bark as possible. Place the soil in the sample box, then deliver the samples to the loading dock area along with the paperwork. (For more detailed instructions, visit the Soil Testing Website.)

Generally, results and recommendations are available within a week to 10 days, but it can take longer in late fall and winter. The Soil Lab’s website offers details on how to interpret the results, with links for further resources. Unless something drastic has changed your soil, like a flood, or you’re making a major change in what you’ll grow — say, an apple orchard in place of petunias — you won’t need to have your soil tested but every three to five years.

This article was originally published on in March 2022.