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Soil and Your Garden

Get the Dirt on Mid-State Soil

Questions & Answers:

My soil contains a lot of clay…

What do I need to do? As you have undoubtedly noticed, soil in south-central Pennsylvania has high clay content. The small clay soil particles compact readily resulting in relatively poor drainage. When planting trees and perennials, you should add peat moss or some other type of organic material (e.g., shredded leaves, mulch, compost) to break up the clay in the soil. Working some organic matter into your garden beds will also help to keep the soil loose and light and improve drainage.

Do I need to mulch?

Mulching is a great way to improve your garden soil. As the mulch decays, nutrients are released into the soil that help to fertilize plants. Note that shredded bark mulch will use nitrogen from the soil as it decays; therefore, make sure to add nitrogen-containing fertilizer back into the soil to aid plant growth. (Ed’s Exclusive slow release fertilizer and liquid fertilizer both contain nitrogen.) Be careful not to use fine-textured mulches such as shredded leaves or grass clippings in thick layers as it can mat down and prevent the soil from getting enough oxygen.

What do I need to know about pH?

The pH measurement of your soil describes the acidity or alkalinity level. A pH of 7 is neutral; any number below 7 is acidic; any number above is alkaline. Most garden plants do well in slightly acidic soil with a pH between 6 and 6.5. Some plants, such as azaleas, foxgloves, heather, and gardenias prefer more acid. For these plants, the soil should have a pH between 4.5 and 6. Other plants, trees, and shrubs like a more alkaline soil. Purple coneflower, phlox, lilac, crape myrtle, and juniper fall into this category. The big-leaf hydrangea changes color depending on the pH level of the soil. This plant turns blue in alkaline soil and pink in acid soil.

How do I know if I have acid soil or alkaline soil?

Generally, mid-state soil will be slightly alkaline. Limestone areas will be slightly more alkaline than areas with a lot of fieldstone. If you plant anything that requires acid soil, such as azaleas or foxglove, make sure to add the appropriate plant food to your soil. Tip: Adding peat moss or other organic matter to your planting holes may help reduce alkalinity by improving drainage and allowing water to wash away the alkaline salts.

How can I test my soil?

The Penn State Agricultural Extension Service lab performs various analyses to test pH and nutrient levels of soil. If you would like to have your soil tested, you must purchase a soil analysis kit. Each kit includes instructions for soil sample collection and handling, a bag to mail the sample to the lab, and a form to provide customer information. The cost of performing the test is included in the purchase price of the kit.

Soil analysis kits may be purchased from county offices of the Penn State Cooperative Extension or at Warburton Greenhouses.