How to Fix Fertiliser Burn

You’ve just fed your lawn and instead of lush green growth, you’re staring at brown, scorched patches. Fertiliser burn is one of the most disheartening lawn problems because it’s entirely self-inflicted. The good news is that most cases are fixable, and your lawn can recover fully with the right approach.

What Causes Fertiliser Burn?

Fertiliser burn happens when grass roots absorb more nitrogen and salts than they can handle. The excess draws moisture out of the grass blades through osmosis, essentially dehydrating the plant from the inside out.

The most common causes are applying too much product, overlapping spreader passes, spilling concentrated fertiliser in one spot, or feeding during hot, dry weather when grass is already stressed. That classic striped pattern of burnt grass usually indicates overlap from a spreader, while random burnt patches often come from spillage or hand-broadcasting errors.

Synthetic fertilisers with high nitrogen content are more likely to cause burn than organic alternatives. The fast-release nitrogen hits grass roots quickly and intensely. Organic feeds release nutrients more slowly, making burn much less likely.

Assess the Damage First

Before you panic, check whether your grass is actually dead or just damaged. Pull gently on the brown grass blades. If they come away easily with no resistance, the roots are dead. If they hold firm, the roots are likely still alive and recovery is possible.

Look at the crown of the grass plant, the white section at the base where blades meet roots. If it’s still firm and shows any green, the grass can recover. If it’s brown and mushy, that section is gone and will need reseeding.

Yellowing grass at the edges of burnt patches is a good sign. It means the damage is superficial and the grass is stressed rather than dead.

Immediate Action: Flush With Water

If you’ve just applied fertiliser and notice burning starting, act fast. The single most effective treatment is flooding the affected area with water to dilute and flush the excess nutrients deeper into the soil, away from the root zone.

Apply at least 2-3cm of water daily for a week. This is significantly more than normal lawn watering. You want to genuinely soak the soil, not just dampen the surface. Early morning watering is best to reduce evaporation.

For small spill areas, you can try to physically remove as much fertiliser as possible before watering. Scrape up visible granules, then flood the area thoroughly.

Recovery Timeline

Mildly burnt grass typically recovers within 2-3 weeks with proper watering. You’ll see the brown fading to yellow, then gradually returning to green as new growth emerges from the crown.

Moderately burnt grass takes 4-6 weeks and may look patchy during recovery. The grass grows back unevenly because some plants were damaged more than others.

Severely burnt patches where the grass is completely dead won’t recover on their own. These areas need reseeding or patching once you’re confident the excess fertiliser has been flushed from the soil, usually after 2-3 weeks of heavy watering.

Reseeding Burnt Patches

For dead patches, wait at least two weeks after the burn before reseeding. This gives time for excess fertiliser to leach away and prevents the same burn happening to your new seedlings.

Rake out the dead grass and loosen the top centimetre of soil. Scatter seed at the rate recommended on the packet, then rake lightly to ensure good soil contact. Keep the area consistently moist until germination.

Fast growing grass seed is ideal for repairs because you’ll see results quickly. The damaged areas blend back in within a few weeks rather than months.

For larger damaged areas, follow the same process as fixing bare patches. The technique is identical, you’re just dealing with a different cause.

Preventing Future Burns

Prevention is far easier than cure. Most fertiliser burn comes down to application errors that are simple to avoid.

Always use a spreader for even distribution. Hand broadcasting looks easy but almost always results in uneven coverage, with some areas getting far too much. A basic rotary spreader costs under £30 and pays for itself in avoided damage.

Calibrate your spreader properly. The settings on the bag are guidelines, and different spreaders vary. Do a test run on concrete or a tarp first to check the spread pattern and rate.

Never overlap passes. Walk in straight lines and use the wheel tracks from your previous pass as a guide. Overlapping means those strips get double the dose.

Follow the recommended feeding schedule and rates. More is not better with lawn feed. Stick to the quantities on the packet and resist the urge to add extra for good measure.

Avoid feeding during drought or heatwaves. Stressed grass is much more susceptible to burn. Wait for cooler, damper conditions or water thoroughly before and after application during summer.

Water after applying granular fertiliser, especially in warm weather. This starts dissolving the granules and moving nutrients into the soil rather than sitting on the surface where they concentrate around grass blades.

What About Liquid Fertilisers?

Liquid feeds are less likely to cause burn than granular products because they’re already diluted and distribute more evenly. However, they can still cause problems if over-applied or used in strong concentrations.

Always dilute liquid feeds according to instructions. The temptation to make a stronger mix is understandable but counterproductive. Apply in the evening or on cloudy days when evaporation is lower.

Long-Term Lawn Health

A healthy, well-maintained lawn is more resilient to fertiliser burn and recovers faster when accidents happen. Regular feeding at appropriate rates builds strong root systems that can handle occasional stress.

If you’re new to lawn care, start with lower application rates and increase gradually as you gain confidence. It’s much easier to add a bit more feed later than to fix burn damage.

Consider switching to slow-release fertilisers if burn is a recurring problem. These products release nutrients gradually over weeks, making accidental overdose much less damaging.

Our beginner’s guide to lawn care covers feeding basics if you want to build confidence with the fundamentals.