How Often Can I Apply Sulfur to My Lawn?

So many things can cause your lawn to look dreadful. Bugs, drought, dull mower blades, weeds … they all take their toll. And sometimes, it’s not any of that — it’s strictly the soil beneath the grass.

Conducting a DIY soil test, or collecting a soil sample for someone else to test, is the best way to determine what your yard needs. If the pH is high, sulfur can help if applied correctly. Here’s what you need to know.

What Does Sulfur Do for Lawns?

“Sulfur is used to correct the pH of very alkaline soils,” says Jay Worth, a turf expert with 14 years in the lawn care industry. “Turfgrass of all species grows best when the soil pH is generally between 6.0 and 7.0.”

If your soil’s pH approaches 7.5 or higher, Worth recommends a sulfur application.

The benefits of applying sulfur to your lawn include:

Corrects the soil’s pH

“In some parts of the South and Western U.S., there are generally more alkaline soils, sandy or loamy soil, necessitating the application of sulfur to lower the pH,” Worth says.

He recommends a soil test. You can buy soil test kits online, at your favorite retailer or local garden center. Online and big box store kits cost $8 to $100.

For a more thorough and accurate test, contact your state’s university extension service. You can find one near you at the United States Department of Agriculture’s National Institute of Food and Agriculture. Click on your state to find contact information on their soil testing services, including pricing.

“If you’ve done a soil test and know your pH is above that ideal range, when to apply sulfur depends on the grass type you’re growing,” Worth says. “If you’ve got a significant issue that needs correction, your best bet is to make these adjustments over a couple of growing seasons. The alternative is possibly destroying your lawn, so patience is key here.”

Note: The Eastern U.S. features a lot of clay soil, which tends to be more acidic. Applying limestone helps raise the pH to a more neutral level in that case.

Helps grass plants produce chlorophyll and properly photosynthesize

“Sulfur is necessary for photosynthesis,” Worth says. “Plants can’t grow and produce chlorophyll without it.”

Most lawn fertilizers include some sulfur, labeled “sulfate” in the ingredients list. You might see ‘ammonium sulfate’ or ‘potassium sulfate.’ If your soil’s pH is a little high, the sulfur in fertilizer can help.

Helps release other nutrients

“When fertilizing your lawn, the plant doesn’t intake those nutrients,” Worth says. “They first adhere to soil particles, and the plants draw nutrients from them.” Generally, sandy and loamy soils hold fewer nutrients than clay soils.

Soil bacteria convert sulfur into sulfuric acid, which releases soil-bound nutrients for plants to absorb. Converting sulfur to sulfuric acid makes more nutrients available in soil that doesn’t hold them well.

How Often Can I Apply Sulfur to My Lawn?

That depends on your turf’s health and soil test results. Applying too much sulfur all at once can damage your lawn.

Generally, apply sulfur once a year. Worth recommends doing it during the fall for best results with cool-season grass types like bluegrass, fescues and perennial rye. For warm-season grasses like Bermuda, zoysia, St. Augustine and centipede, apply during spring before the onset of summer heat.

“Soil permeability plays a huge part too,” Worth says. “If your soil is extremely compacted and you’ve got standing water on your property, sulfur might cause damage. If you think this might be the case, core aerating your lawn before applying the sulfur treatment will help.”

How to Apply Sulfur to Your Lawn

Some soil test results tell you how much sulfur to apply to correct the pH. You may need to use only a turf fertilizer with sulfur to even out the pH, or apply sulfur once a season for three years.

Sulfur for turf comes in dust, wettable powder, liquid and pellet form. Always read the instructions on the packaging for recommended spreader gauge settings, how much to use, and whether you need to water it into the soil.

You can buy lawn fertilizer with sulfates as a liquid applied with a hose-end sprayer, or as granular fertilizer applied with a spreader. Use a broadcast spreader for lawns 4,000 square feet or more. Choose a drop spreader for lawns with a lot of landscaping and hardscaping and smaller-sized yards.

Caution!

If you apply sulfur to your lawn, keep your children and pets away from the area until it dissolves into the ground. Sulfur has been registered as a pesticide since the 1920s. It can kill insects, mites, rodents and fungi.