Why Your Lawn Is Brown or Patchy in May – and How to Green Up Your Grass, Fast

By May, the weather is warm enough for your grass to be growing and looking green as green can be. So, if your lawn is less than lush this spring, there’s a problem! But don’t fret if you have brown grass or even patches of dead grass: there’s still time to work out what it needs, and fix the issue to enjoy a verdant green lawn all summer. Wait until June’s heat arrives before you take action, however, and you’ll be fighting a losing battle.

Your first task is to turn detective and work out what your lawn is lacking, then it’s a simple step to give the grass what it needs, and nature will sort the rest. At this time of the year, it’s very unlikely that your grass is suffering from lack of moisture so you can rule that cause out unless the weather has been mighty dry in your area. Your lacklustre grass is far more likely to be caused by one of seven common problems, which are all easy to fix with the right lawn care in May.

I've included some links to a certain national retailer, just so you can see the exact type of product you need to get the best results – but do support your local businesses too.

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Right, let's get this problem sorted! Which of these issues are behind your patchy brown lawn?

1. You’ve Been Mowing Your Lawn Too Short

Fetch a ruler and go measure how tall your grass is. Done? If it's less than 1½ inches high and you recently mowed, this is the likely cause. In spring, grass wakes up from its winter dormancy and starts growing. The plants are full of nitrogen at this time of the year, which fuels strong foliage growth. But if you’re continually cutting those blades too short, your grass plants are using up more energy than they’re able to make.

Think of all those grass blades as solar panels. In spring, while the plants are in full growth, it’s best to leave the blades a little longer so those solar panels can generate more energy. That means the plants have enough energy to fuel not just foliage growth but root growth.

In spring, it’s best not to mow your lawn any shorter than 1½ inches above the ground. Sure, you can gradually reduce the height to around 1 inch as summer approaches but for now, keep your mower a little higher. There's an added benefit of raising your mower height in spring because there’s a direct correlation between the grass' height and its root depth. Encourage your grass to grow its root system a little deeper now and, come summer, it'll be better able to seek out moisture. So, allowing that extra half-inch of grass height won't just help your lawn green up now, but help it stay greener for longer in the summer heat.

2. Your Lawnmower Blades Are Blunt

Take a closer look at your grass: is it just the tips that have turned brown? Cutting a blade of grass with a blunt mower blade is rather like trying to slice a tomato with a less-than-sharp knife: you’ll just squash and bruise it. And the thousands of raggedy, torn edges you create when you mow with a blunt blade will be slow to heal and likely turn brown.

It’s a quick and easy job to sharpen mower blades, and experts suggest you resharpen after every eight hours of mowing – yes, you read that right, not eight months or years! You’ll need a dual-grit sharpening file such as this from Amazon or you can use blade-sharpening bits such as these from Amazon that fit any standard power drill.

All you need do is repeatedly run the sharpener along the blade at an angle to create a fine edge. An angle of around 30° is about right but simply aim to match the factory-set bevel, which may be up to 45°. To do a good job, all you need is to understand that a blunt blade edge is wide, whereas a sharp blade edge is far narrower. So, if you’re using a manual sharpening file, first use the coarser side to remove any notches from the blade, then the finer side to get that super-narrow edge.

If you’re worried about getting the angle right, then a sharpening tool such as this Sharpal Multi-Blade Sharpener, available from Amazon, is foolproof.

Before you start, make sure your lawnmower is disconnected from its power source – and that includes removing the battery from a cordless mower as well as unplugging an electric mower. With most mower designs, it’s easiest to remove the blade from the chassis by undoing the mounting nut, and do wear heavy-duty gloves such as these from Amazon.

3. The Soil Beneath Your Lawn is Compacted

If your grass is brown in patches, and you noticed any standing water after heavy rain over the winter, then chances are the soil is compacted. It’s a common problem with lawns as they’re usually heavy-traffic areas, especially if you have kids. And when soil becomes compacted, it’s difficult for water, air and nutrients to filter down into it, and grass roots start to struggle.

Thankfully, it’s an easy issue to fix by creating a myriad small holes all over your lawn. If your lawn is small then it’s easy to do by pushing the tines of a garden fork into the soil. For a bigger lawn, you’ll want to make life easier with a rolling aerator such as this from Amazon, or a pair of spiked soles such as these, also from Amazon.

Switch up the pattern that you mow in, too, as a regular route could be contributing to soil compaction. Adopt a different approach every time you cut the grass, switching between straight and diagonal lines, cross-hatching and spiralling out from the centre.

4. Your Grass is Hungry For a Spring Feed

Does your grass look pale, or have any yellowing blades, and is growth patchy or sparse? These are signs that your lawn needs feeding. It’s a smart move to feed your lawn every spring, even if it's already beautifully green, and it’s easy to do.

If you have a mulching mode on your mower, use that to chop the grass clippings into a fine mulch which will slowly break down to feed the lawn. For a faster result, use a granular lawn fertilizer that prompts root as well as shoot growth, and releases nutrients over a long time period, such as this from Amazon. Follow the instructions on the packet and don’t be tempted to over-fertilize as that causes just as many problems as under-fertilizing. Mixing the lawn feed with a few handfuls of sand helps you see the areas you’ve treated, but do always wear gloves when handling fertilizers.

5. You've Over-Fertilized Your Lawn

If you recently fertilized your lawn and it's now looking decidedly brown, you've likely used too high a concentration of feed and damaged the grass. You'll need to act quickly to save the grass, flooding it with water every day for at least the next week to dilute the excess salts.

Your grass will hopefully recover but if not, treat your lawn as if it's full of moss, below.

6. Your Lawn is Full of Moss

Moss loves to make itself at home in a lawn, gradually building up among the grass. Which is fine while the weather is cool and damp enough for the moss to stay green but, as soon as we hit May and temperatures rise, it quickly dehydrates and turns brown.

There’s another problem with excess moss in your lawn, too, as it can choke healthy grass growth. Evict it and you won’t just have a greener lawn but room to grow a denser sward that looks far plusher and stays lush for longer.

With a springtine rake such as this from Amazon, rake the grass to pull the moss out. You’ll also drag any dead grass, or thatch, out. If you’ve got a big lawn, then an electric scarifier like this from Amazon speeds up the job.

Afterwards, there will likely be a few bare patches that need reseeding, and a bare spot lawn repair mix such as this from Amazon will give quick results. However, if you pulled so much moss from your lawn that the grass looks a little sparse all over, then now’s a great time to overseed. Because you’ve already scratched the soil surface with your raking, grass seed will germinate quickly and find it easy to send roots down into the ground – just be sure to treat your baby grass plants as you would any freshly-sown garden additions, and keep them well-watered to start with. Choose grass seed that’s suitable for your lawn conditions, for best results.

7. The Grass Has Been Burnt By Dog Pee

No prizes for guessing how to work out if this is the cause of your brown lawn patches! Dog urine contains high levels of nitrogen which can chemically burn the patches of grass it first hits; the surrounding area is likely to grow a darker green because of that extra nitrogen, too.

Your best bet is to use a product that neutralizes the acidity of urine-damaged soil and allows the grass to regrow, such as this from Amazon. Do check the fine print when you’re looking for burn-spot lawn repair treatments, as some are dyes that simply paint your dead grass green! Going forwards, natural dog chews that balance nitrogen levels in urine will reduce the issue, like these from Amazon.

All sorted? Then you have a summer of lush green grass ahead of you!

Prevention is far easier than cure when it comes to lawns, so consider adopting an annual spring lawn care routine that sets your grass up for healthy, abundant growth all year long. Brown patches of grass can also be caused by lawn fungus or lawn grubs, but these are typically more likely in late summer through autumn.