A well-fed lawn not only looks better, but also stands up to drought, insects, foot traffic, and other stress better. Your lawn needs both the right fertilizer and the right fertilization schedule to help it make the most of good growing weather and survive dormancy.
Most lawns benefit from fertilization two to four times a year, but how often you’ll need to feed your lawn depends on your grass type, climate, and how much time you want to invest.
Nutrition for New Grass
Whether it’s seeded, sodded, or sprigged over a whole lawn or a small bare spot, new grass benefits from extra nutrients. For good quality soil, adding an inch or two of compost might be all you need to do.
If your soil is less than ideal, apply starter fertilizer. This fertilizer is specially formulated for new lawns and contains higher levels of nutrients, phosphorous in particular, to help seeds sprout and seedlings grow strong, deep roots. Many also contain quick-release nitrogen to promote seed germination.
Before planting, apply the fertilizer with a lawn spreader, but don’t rake it in. The fertilizer should go no deeper than 4 inches to prevent damage to the grass’ roots. Wait until after the third mowing to fertilize again.
The Right Feeding Schedule for Your Grass Type
Overfertilizing promotes excess leaf growth at the expense of root growth, or worse, creates an unhealthy pH and nutrient balance, and a harmful buildup of salts. Before you decide on your fertilization schedule, read your fertilizer’s label to find out how long it’s formulated to last. Some time-released formulas continuously release nutrients for as long as 12 months, and reapplying to soon leads to over fertilization.
In general, plan to fertilize two to four times or around once every six to eight weeks, applying the bulk of the lawn’s yearly fertilizer during its most active growth period. Your grass’ active growth period depends on whether it’s a cool-season species, such as Kentucky bluegrass or tall fescue, or a warm-season species, such as Bermudagrass or St. Augustine grass.
Spring and fall are the active growing times for cool-season grasses, so that’s when you’ll want to provide most of the year’s fertilizer. In summer, when growth is slower, these grasses need little to no feeding. Warm-season grasses are most active in summer, so they need most of their nutrition between late spring to early fall. Because they slow down once the weather cools, they don’t benefit from late-fall fertilization.
If you live in the grass transitional zone, your lawn might have a combination of warm- and cool-season grasses that will need a compromise between the two schedules. Regardless of your grass species, avoid fertilizing when the lawn is dormant. Doing that only helps the weeds.
Fertilizing Across the Seasons
Both the weather and your climate affect your lawn’s need for nutrients.
Both cool- and warm-season grasses are active in spring, and fertilizing gives them the nutrients they need to grow. Cool-season grasses can be fertilized when the soil temperature reaches 55 degrees. In most parts of the country, that’s around mid-April. It’s also when the grass first starts growing, and the lilacs start blooming.
To time it more accurately, use a soil thermometer. If you plan to use a weed-and-feed product, apply it shortly before the soil reaches 55 degrees to head off weed growth.
While cool-season grasses can be fed earlier in spring than their warm-season cousins, avoid feeding them too early. You’ll encourage leaf growth instead of root growth, which makes for an overall weaker lawn. It’s all right to delay fertilization for awhile after a long, hard winter.
In fact, if you fertilized late in the previous fall, you don’t need to worry about fertilizing again until late spring. To further reduce the risk of excess leaf growth, choose slow-release fertilizers.
Fertilize warm-season grass once it’s been growing long enough to need mowing, which is usually when the soil temperature has been at around 65 degrees for several weeks. If you live in a warm climate with no winter dormancy period, fertilize in April. Feeding too early in spring promotes growth before the grass is ready for it.
If needed, fertilize again in late spring between April and June or six to eight weeks after the early spring feeding. If you plan to overseed, avoid weed-and-feed products for four weeks before overseeding. After overseeding, wait until the third mowing to fertilize.
Good fertilization helps grass survive the heat, drought, and foot traffic of summer. Cool-season grasses naturally slow their growth in warmer weather, so don’t fertilize during the hottest part of the summer. Wait until late summer or early fall when the weather is starting to cool off, then apply a slow-release fertilizer with moderate nitrogen content.
The exceptions are cool-season grasses in cool-summer climates, such as the Pacific Northwest, parts of the Northeast, and some high elevation areas. It’s safe to feed these lawns in summer, but apply less fertilizer than you have planned for the end of the season.
For warm-season grasses, summer is the most important feeding time. Apply fertilizer once between June and August, around six to eight weeks after the late spring feeding. Then fertilize every six to eight weeks, making the last application four weeks before the first frost. Make the last application of nitrogen fertilizer no later than eight weeks before the first frost.
For the final summer feeding, consider an organic fertilizer such as compost or manure. Alternatively, if your soil tests low in potassium, your grass might benefit from a low-nitrogen potash fertilizer.
Cool-season grasses do much of their growing in fall, so they need good nutrition then. In cold-winter climates, late autumn feeding helps the grass recover from the summer heat and build up the reserves it needs to come back strong in spring after winter dormancy. In milder climates, where cool-season grasses stay green all winter, fall feeding keeps the grass healthy through this season.
In late fall, six to eight weeks after the late summer or early fall feeding, apply a winterizing fertilizer. Do this when the grass is still green, but has stopped growing, which usually happens when air temperatures are in the mid-50s. Formulated to help grass prepare for the cold season, winterizing fertilizers are high in phosphorous and potassium, which promote root growth, but lower in nitrogen to avoid promoting unnecessary leaf growth.
Warm-season grasses are slowing down in preparation for winter dormancy, so they don’t need extra nutrition, and winterizing fertilizer isn’t recommended. Fertilizing at this time leaves warm-season grass vulnerable to winter damage by causing it to put its energy into leaf growth when it should be storing energy for winter.
Once you understand your grass species’ seasonal growth pattern, you can give it the right nutrition when it needs it most. Well-planned fertilization like this keeps your lawn lush and green during the growing season and protects it from damage during dormancy.