At Home: Before planting your garden, test the soil

Make sure the pH level is suitable for vegetables, flowers

If your garden didn’t do as well as you wanted last year — your annuals didn’t flower much and you didn’t get many vegetables — it’s probably time to get the soil tested.


Dave Jackson, owner of Jackson Greenhouse and Garden Center Inc., 1933 N.W. Lower Silver Lake Road, said testing the pH of the soil is really important to determine if it’s suitable for planting.

“In my view, that’s the key to everything in terms of being successful,” Jackson said.

With the exception of sweet corn, which likes a higher pH level, most vegetables and flowers are going to need soil with a pH range of 6.0 to 6.8, he noted, adding one point can make all the difference.

“They can bring in their (soil) sample, and we’ll test it,” Jackson said, adding testing takes about 15 minutes and his staff will provide recommendations based on the findings.

If it’s an older garden with soil that hasn’t been tested in a while, he recommends having it tested at the Shawnee County Extension Office, 1740 S.W. Western Ave.

When to test

Jamie Kidd, Shawnee County Extension horticulture agent, said if pH levels are off then food can’t get from the soil to the plant.

If the soil’s pH is too high, you’ll need to add sulfur. If it’s too low, you should add lime.

“People think you should add lime every year,” she said. “You shouldn’t do it unless your soil’s pH is too low and acidic.”

Kidd recommends having the soil tested every three years. She suggests rotating the tests each year — one year, get the garden soil tested; the next year, flower garden soil; the third, turf.

Shawnee County Extension offers one free soil test to Shawnee County residents each year through a grant. If you need more than one test or are a nonresident, the cost is $10. By rotating the tests each year, you can get all of your soil tested for free. To learn more about the Extension’s soil testing program, visit


and composting

Once you have the pH levels lined out, you’ll need to add fertilizer to help the plants produce the energy needed to grow. Fertilizer contains nitrogen, potassium and phosphates.

“Everybody is going to need nitrogen,” Kidd advised.

When you get the soil tested, you also can find out how much fertilizer you need to add. Another thing you might be considering — or are already trying — is composting. But be aware: If compost hasn’t broken down all the way, Jackson warned, it will start absorbing nitrogen.

“Anything green will take nitrates from the soil and will compete with plants,” he explained.

Jackson said most experienced gardeners will let compost break down for six months or more before putting it to use. He recommends turning it often to help speed up the process.

Another way to tell if compost is ready to use is to check the smell.

“If it’s balanced correctly, it won’t stink,” Kidd said.

However, if you’re counting on compost to help boost nitrogen levels, it likely won’t help all that much.

“Compost is not high in nitrogen,” Kidd said.

What it can do, she said, is help clay soil drain more effectively and sandy soil hold more water.