If you have a yard, chances are you’ll have fertilized your lawn at some point. Fertilizer promotes thick healthy grass and keeps your lawn free from weeds and pests. But if you overdo it, there can be consequences.
We take you through how to spot fertilizer burn, as well as how to fix your over-fertilized lawn. Follow these steps to get your burnt grass green again.
Fertilizers contain a lot of salt. When you add salt to your lawn, it draws water out of the soil. If you add too much salt, then there’ll be no water left for the grass, causing it to dry out.
This is called fertilizer burn.
Fertilizer burn most commonly results from spillages, uneven spreading of fertilizer, or overuse of fertilizer. Dog urine can also be the culprit. It contains lots of nitrogen which is known to harm grass in high concentrations.
Stressed grass is more susceptible to over-fertilization because it’s less able to absorb the minerals from the fertilizer. This leads to a build-up of those minerals in the soil and eventually fertilizer burn.
If you’ve just spilt a whole bottle of fertilizer over one patch of your lawn, you don’t need a guide on the internet to tell you that you’ve over-fertilized. However, sometimes it’s not so obvious. Here are five signs that you’ve gone overboard with the fertilizer:
The main thing to look out for is yellow or brown grass.
You can sometimes also see streaks of burn on your grass where the fertilizer touched the blades. Fertilizer burn tends to appear in the day or two after you applied the fertilizer.
There might only be small patches of damage, or there could be more significant areas where you’ve accidentally overlapped too many times when spreading the fertilizer.
Sometimes see a layer of white crust forming on the surface of the lawn and around the edges. This is a sign the ground is not absorbing the fertilizer properly, likely because it already has enough minerals.
In the summer it can be hard to tell if your grass is dormant, or if it’s being affected by over-fertilization. Looking at the roots is a good way to check. Root damaged by over-fertilization wither and turn brown or black. This is known as black root.
A longer-term sign of over-fertilization is slow-growing grass. After fertilizing you’d expect to see your grass flourishing. If this doesn’t happen, and growth seems slower than usual, then you may have over-fertilized.
Monitor your lawn closely after any fertilization application and look out for the signs we’ve mentioned. Fertilizer burn is progressive. The faster you catch it, the quicker you can act and the easier it’ll be to fix.
The simple answer to how to fix an over-fertilized lawn is to water it. A lot. If the grass doesn’t revive itself in a few weeks, you’ll have to reseed it.
If you suspect over-fertilization, you should assess the damage before taking any action. This will give you an idea of how bad the problem is.
Make a note of how many dry patches you see and the condition of the grass. If the grass is yellow but still feels moist to touch, the grass is alive and will grow back. If it’s leaning towards brown and feels brittle, the grass is likely dead and won’t grow back.
Don’t forget to check the roots as well. If the roots look generally healthy, then the burn is only superficial. If you spot any black roots, the problem is more severe. Make sure to check the roots in a few different spots to see how widespread the damage is.
If the fertilizer burn has only affected the surface of the lawn (and the roots look healthy), watering should be enough to get your grass looking green again.
Even if this is not the case, watering is still the first step in fixing your lawn, because you need to flush out the fertilizer before planting any new grass.
As soon as you become aware of the issue, water your lawn until it’s fully saturated and can’t absorb any more water.
Watering your lawn helps to dilute the fertilizer and encourages it to sit deeper in the soil. By sitting deeper, it won’t be in direct contact with the grassroots and therefore causes less damage.
Water slowly but deeply to prevent runoff. If you apply a lot of water too fast, the lawn might not be able to absorb it. You risk the water leaking into nearby water sources and contaminating them with fertilizer.
Even if the fertilizer burn only affects parts of your lawn, it’s better to treat the whole area. By doing so, you don’t just push the fertilizer into a non-affected patch of grass.
Water sprinklers make this job a lot easier. They’re more likely to provide even coverage and don’t require much time investment from you. We recommend this oscillating sprinkler from Melnor. You simply connect it to your garden hose and place it in the middle of your lawn; it can cover up to 4000 sq ft in one go.
After the initial watering, water your lawn every day for the next week. Apply about an inch of water each time.
The best time to water the grass is in the morning. This gives the grass all day to dry out. If you leave the grass wet overnight, then it’s more likely to develop a fungal disease.
Once you’ve watered the lawn enough to dilute the excess fertilizer, the grass should start to perk up within one to two weeks. If it does, then you’re home and dry and can go back to your normal lawn care routine.
If it doesn’t, which is likely if you had root damage, you’ll have to reseed the dead grass patches.
This will remove any competition that might prevent your new grass seeds from growing. Next, sprinkle the new grass seed and then topdress the soil with compost.
Check out our article on the best way to spread compost on a lawn for ideas on how to spread the compost.
You’ll have to the water the new seedlings attentively for the next few weeks until they’ve germinated. Once they’ve sprouted, your lawn will be back to normal in no time.
To learn more about reseeding check out our guide on reseeding your lawn.
Over-fertilizing your lawn once is bad enough, but doing it twice would be a nightmare. Here are some tips to reduce the risk of it happening again:
It’s easy to see where you’ve put too many fertilizer granules down, and you have the chance to pick them up before they cause any damage to the lawn. This is much harder, or impossible, with powder and liquid fertilizers.
If compost isn’t for you, then look at using a slow-release fertilizer. Because the salts are released gradually rather than all in one go it’s much less likely to cause fertilizer burn.
Whatever fertilizer you use, make sure to read and follow the instructions carefully. If you rush any calculations, you can easily overestimate how much fertilizer you need. Take your time and double-check before you spread anything.
Fertilizer can stick to wet grass blades rather than getting dispersed.
Hopefully, this article has helped you to troubleshoot and fix your over-fertilized lawn. It’s never a good situation to be in having to ask this question. But with a few simple steps, you can mitigate most of the damage and be on track to having a vibrant and healthy lawn.
Make sure to check out the rest of our lawn care tips such as how to tell if your lawn needs lime.
Veronica has a passion for all things eco-friendly. After growing up on a farm in Ireland, she went on to study Chemistry and Environmental Sciences. Veronica has also volunteered in many sustainability roles, including conservation efforts in Bangladesh and teaching Environmental Sciences to schoolchildren in Kenya.