How to Avoid Fertilizer Burn on Lawns

Feeling the burn might good during a workout, but you don’t want to feel — or see — the burn after fertilizing your lawn. Have you noticed yellow or brown patches several days after applying fertilizer to your otherwise healthy lawn? If so, you may have fertilizer burn. Read on to learn how to avoid this grass-killing phenomenon. If it’s too late for that, we’ve also got some pointers on how to repair the damage.

Causes

So what exactly is fertilizer burn? It’s what can happen to your lawn or garden when you over-fertilize. It can also occur when you apply fertilizer to wet grass or plants. Your previously green foliage will look scorched: It will turn yellow, then brown. This can happen within a day or two, or it can take several weeks with a slow-release fertilizer.

The Michigan State University Extension office offers this advice: “Look for turf fertilizers that have at least a portion, 25 percent or more, of their nitrogen in the form of slow-release N [nitrogen].” Organic lawn fertilizer is another good choice. It doesn’t contain synthetic chemicals, so it’s less likely to burn your lawn.

Fertilizer burn happens because fertilizers contain salts that can draw moisture away from grass and plants, causing them to dry out and turn brown. This damage can show up in stripes from overlapping spreader rows, or in larger patches on your lawn. Oregon State University’s Extension department suggests that you “water long enough to wash granules off foliage or until granules completely dissolve.”

Use our guide on When and How to Fertilize Your Lawn correctly to learn how to apply the right fertilizer in the right amount at the right time. Done correctly, fertilization will help your grass, not burn it.

How to Fix Fertilizer Burn

Your lawn can recover from fertilizer burn. If the damage is limited to the leaves or blades, but the roots are OK, you can fix it easily. If the roots are damaged, it’ll take more effort. 

Your first step is to check the roots as soon as you notice any yellow or brown spots. Check the roots in more than one spot. If the roots are healthy and not dried out, you’ll need only to water the grass to dilute and remove excess fertilizer.

Water, Water, Water

No matter how much damage you have, you’ll need to water, water, and water the affected areas. When you’re done with that, you’ll need to water some more. Water helps carry the fertilizer salts into the soil and dilutes their concentration. Give the damaged areas at least an inch of water a day for a week or more.  Remember to water in the morning so the water has time to evaporate off the grass blades. This will prevent the additional problem of fungal disease. Using sprinklers will help you evenly distribute the water. Watering unaffected areas will help the fertilizer salts leach through the soil throughout the yard, rather than keeping them concentrated in one area.

Monitor the Comeback

You should start to see new growth by the end of the first week, or a few days after that. If not, you’ve probably got root damage. Check the roots in the affected areas again. If the roots are shriveled and brown after a week of watering, they’re past the point of saving. You’ll need to reseed or re-sod those areas. Don’t start this process before you’ve watered, because you need to flush the minerals out of the soil. Otherwise, you’ll have the same problem with your replanting.

After correcting the burn, preventing it from happening again is a matter of basic lawn care. Following these tips can help keep your lawn looking green and healthy without unsightly signs of fertilizer burn. Applying fertilizer correctly will let it do its job of nourishing your lawn, rather than damaging it.

FAQ About Fertilizer Burn

What kind of fertilizer causes fertilizer burn?

Immediate-release fertilizers, liquid fertilizers, and synthetic fertilizers are most likely to burn your grass. To reduce the risk of fertilizer burn, choose a slow-release, granular, organic lawn fertilizer. Learn more in our article How to Choose Lawn Fertilizer.

Does timing affect fertilizer burn?

Yes, applying fertilizer at the wrong time of year can cause fertilizer burn. Never fertilize when your grass is dormant or when it’s under stress from drought, extreme heat, lawn disease, or pests. To find out the best time to fertilize your lawn depending on your grass type, check out our recommended lawn fertilizer schedule.

What grass types are most vulnerable to fertilizer burn?

Since fertilizer burn is caused by too much nitrogen in the soil, grass types with low nitrogen needs are the easiest to burn. Fine fescues, centipedegrass, and Bahiagrass can get by with very little nitrogen and therefore are easy to overfertilize. Kentucky bluegrass and perennial ryegrass, on the other hand, need much more nitrogen than other grass types and may be harder to burn.

Main image credit: Sten Porse, CC by-SA 3.0