Fertilizer is food for your grass, but sometimes feeding your lawn can actually be a bad idea. The best time to fertilize your lawn is when the grass is actively growing. Applying fertilizer at the wrong time can set up new growth for failure and even help unwanted weeds to thrive.
Lawn fertilizer can be found at any home and garden store. The packages are marked with three numbers, such as 10-10-10, which refer to the percentages of nitrogen, phosphorus and potassium — always in that order. These three nutrients are vital for healthy grass, but different seasons call for different approaches.
Fertilizing Warm Season Grass
DON’T apply nitrogen in the fall.
Applying nitrogen-rich fertilizer to these grasses in fall, especially within six weeks of the first frost, would be largely wasted since growth slows down in the transition to dormancy. Also, tender new growth prompted by fall nitrogen is more susceptible to winter’s bite.
Worst of all, when you add nitrogen to warm season grass too late in the fall, you inadvertently feed the cool season weeds that thrive while your lawn lies dormant. Don’t encourage the weeds! The best time to fertilize a warm season lawn is late spring, then add a nitrogen rich fertilizer every four to six weeks through mid-summer when growth is most active.
DO apply phosphorus and potassium.
Giving your lawn a boost of phosphorus and potassium before winter is a great idea, however. Potassium helps protect grass from winter’s chill, and phosphorus gives the grass what it needs to store energy for a beautiful spring green-up. Look for fertilizers with a lower first number, like 6-12-18 or 4-12-12.
Fertilizing Cool Season Grass
Grasses that stay green year-round, like tall fescue, thrive during the cooler temperatures of fall and spring.
DO apply nitrogen in the fall.
October and November are the best time to fertilize a Fescue lawn, supporting rapid growth with nitrogen and other nutrients.
DON’T fertilize in late spring.
You can fertilize again in early spring, but avoid over-fertilizing in late spring and summer, when fescue growth slows.
DO soil test for best results.
If you’re preparing to fertilize a Fescue lawn and you haven’t tested your soil in two years or more, send samples to your county Extension Service first. (Find your county office at extension.uga.edu/county-offices.) You will receive a report letting you know exactly which nutrients need to be added to amend your soil. A pH reading will also include recommendations to help balance the acidity of your soil. Following the Extension Service guidelines will give your grass exactly what it needs to grow healthy and strong, helping ward off disease, pests and weeds.
If you have amended your soil recently, look for a general lawn fertilizer at your garden supply center that includes a balance of nitrogen, phosphorus and potassium.
More Fertilizing Tips:
• DON’T use weed and feed products.
To control weeds, it’s best to apply a pre-emergent herbicide in late winter, when the forsythia blooms, and again in the fall—which are not optimal times to fertilize.
• DO use a mulching mower.
Leaving mulched clippings on the yard can reduce your lawn’s need for fertilizer by up to half. Mulching mowers break grass clippings into tiny bits that drop to the soil surface where they become food for your lawn.
• DON’T overwater.
Excess irrigation, especially of sandy soils, increases fertilizer requirements.
• DON’T fertilize wet grass.
The fertilizer may cling to the wet blades and cause the grass to burn.
• DO water-in the fertilizer.
Watering the grass after fertilizer application (or fertilizing just before a soaking rain) helps ensure the nutrients get to the grass’ roots.
• DO use a broadcast spreader.
You’ll get a more even application than if you try to fertilize by hand.