How Long After Fertilizing Should I Apply Lime?by Rob Hainer
Keeping your lawn green and healthy takes maintenance, including applying fertilizer and lime periodically. When you apply both products depends on what your soil needs. In many cases, it's safe to apply both on the same day, but sometimes it's best to stagger the applications. Pick a day when your kids aren't playing outside to apply both products to make sure they don't accidentally ingest any of the chemicals.
Different types of fertilizer provide essential nutrients to the soil, but lime affects the soil's acidity, or pH, level. Most lawns need a pH of between 6.0 and 7.0 When the pH falls below those levels, your grass can't adequately absorb nutrients -- including those provided by fertilizer -- such as nitrogen, phosphorus, potassium and magnesium. Lime raises your soil's pH so the grass can get the food it needs. A soil test helps you decide how much lime to add. If your soil is below a pH of 6.0, add at least 100 pounds of lime per 1,000 square feet of lawn. If you're adding lime just to maintain pH levels, add about 50 pounds per 1,000 square feet.
When planting seed, it's best to space out fertilizer and lime applications, especially in warm weather. Applying the fertilizer first helps get the necessary nutrients in the soil so the seeds can germinate properly. Adding lime seven to 10 days later gives the soil an added boost so the newly formed roots can access the fertilizer's nutrients.
When your lawn doesn't need a big influx of lime to raise the pH, you don't have to wait after applying fertilizer before you apply the lime as part of your regular lawn maintenance. If you're not adding more than 50 pounds per 1,000 square feet, you can apply both on the same day -- just not at the same time. To ensure even coverage of both materials, spread the fertilizer with a seed spreader over your entire lawn. After emptying the spreader, fill it with lime and apply that to your lawn as well. When your pH levels regularly stay between 6.0 and 7.0, you don't need to apply lime with every fertilizer treatment. Instead, add it once every two years.
Sometimes, it makes sense to apply lime before fertilizing your lawn, instead of the other way around. Because grass can't take in fertilizer's nutrients when the soil pH levels are too low, you shouldn't fertilize first if a soil test registers a low pH. Liming first helps raise the pH so that when you fertilize, the grass is ready and waiting for nitrogen and other nutrients. Pelletized lime works faster than some other lime products, but you must often wait at least a couple of months for it to change the soil's pH before adding fertilizer. Slower versions, such as dolomitic limestone, can take up to 150 days to alter the pH.
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