Sulfur and Soil pH

Sulfur can raise soil’s acidity—a benefit to gardeners, especially if the soil is too alkaline. The acidity and alkalinity of soil is determined by its pH level, measured on a scale of 0 to 14, with 7 being the neutral point.

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Anything below 7 is considered acidic, and anything above 7 is alkaline. Most plants thrive in neutral pH levels of 6.5 to 7.5, but some, like blueberries and azaleas, thrive in acidic environments, preferring a pH level of 4.5 to 5.5.

Identifying a sulfur deficiency in your garden

There are various ways to augment sulfur in the soil to benefit plants and crops. But first, you need to determine if additional sulfur is actually needed. Indications that plants may be suffering a sulfur deficiency include stunted growth, poor crop yield, and the yellowing of new leaves (as opposed to the yellowing of older leaves which may indicate a nitrogen deficiency). If you suspect a sulfur deficiency in your soil, purchase a soil testing kit. Make sure to test various areas of your garden, not just one spot, for the most comprehensive results. Once you receive the results, you can augment your soil’s sulfur content (and add any other elements needed) to resolve deficiencies and enhance plant growth.

3 Ways to Add Sulfur to Your Garden

If you have a sulfur deficiency in your garden, here are some cost-effective ways to augment the soil’s sulfur content: Start by tilling sulfur-rich material into the ground, at least 6 to 10 inches deep. If plants are already in the ground, it will be harder to penetrate the soil without damaging the plants and their root systems. You can sprinkle sulfur powder or pellets on top of the soil and use a rake to distribute the material (being careful not to damage stems, leaves, and roots), but this method is slow going as you’ll have to wait for the surrounding area to absorb the element. And adding too much sulfur too quickly can cause plants to die. How much sulfur do you need in your garden? Use this handy calculator.

Tips for Acid-Rich Soil:

Flowers and Plants That Thrive in Acidic Soil

Hydrangeas (certain cultivars will turn from pink to blue, and the blue ones will turn a deeper shade of blue) Camellias Gardenias Magnolias Zinnias Foxglove Blueberries Cranberries Gooseberries Evergreens Peppers Tomatoes Potatoes Squash Rhubarb Azaleas Rhododendrons Most evergreen shrubs and trees Dogwood Magnolia