Patchy, dry or yellow lawn: how to revive it

A ruined lawn can almost always be revived without digging the whole thing up. The key is to diagnose the cause properly before acting: a bare patch from compaction is not the same as one from a fungus or from dog urine, and the treatment is different in each case. Once the problem is identified, the recovery plan is similar - aerate, scarify, top-dress and overseed - and the best time to do it is autumn.

This guide helps you identify what's wrong with your lawn from what you see, then gives you the step-by-step recovery plan and the calendar so that it's dense again within a season. Ten FAQs at the end.

Diagnosis: what's wrong with your lawn

The step-by-step recovery plan

1. Mow and clear

Mow the lawn a bit lower than usual (about 3-4 cm) and collect the clipping. Rake hard to pull out dead grass, moss and leaves. You'll see how much material comes out: that's what was smothering the base.

2. Scarify

The scarifier has vertical blades that cut and pull out the thatch (the layer of debris between the grass and the soil). A little thatch is good; more than 1 cm stops water and air reaching the root. Run the scarifier in two perpendicular directions and collect everything it pulls out. The lawn will look "bald" and rough for a week: that's normal, it's the most aggressive and necessary part.

Affiliate link: if you buy through it, TuJardínPerfecto may earn a small commission at no extra cost to you. More information in the affiliate disclosure.

3. Aerate

If the soil is compacted (bare patches in traffic areas, water that stays pooled, hard soil when you push in a screwdriver), aerate it: a hollow-tine aerator pulls out "cores" of soil and leaves holes the root can breathe through. On small areas, push a fork in every 10 cm and rock it slightly. Do it with moist soil, not waterlogged or dry.

4. Top-dressing

Spread a thin layer (0.5-1 cm) of top dressing - a mix of sand and sieved compost, or a specific lawn dressing - over the whole lawn and, above all, filling the bare patches and the dips. Spread it with the back of a rake. Top dressing levels, adds organic matter and creates the perfect bed for the new seed.

5. Overseed

Spread seed of a mix suited to your situation (20-25 g/m² generally, denser on the bare patches), cover with a light pass of the rake or a bit more top dressing, and firm lightly. If you have many bare patches together, treat them as a new sowing: see how to sow a lawn step by step.

6. Watering and starter feed

Water lightly 2-3 times a day for the first 2-3 weeks so the seed doesn't dry out, then move to one watering a day and then to normal watering. At 4-6 weeks, apply a starter fertiliser (rich in phosphorus, which favours the root) or a slow-release one at half rate.

When to do each step

When it's not worth reviving

If more than 50% of the surface is weeds or bare patches, if the soil has a serious underlying problem (impossible drainage, total shade, rubble under 5 cm of soil) or if the lawn was laid over badly prepared ground and has never done well, it's more worthwhile to start over: remove everything, prepare the ground properly and sow. Reviving makes sense when the base is reasonable and the damage is superficial or localised.

Quick glossary

• Bare patch: an area with no grass, from compaction, fungus, dog urine, a root pest or a failed sowing.
• Thatch: a layer of undecomposed stems and roots between the grass and the soil; more than 1 cm waterproofs it and suffocates the root.
• Scarifying: pulling out the thatch with vertical blades; done once a year, in autumn or spring.
• Aerating: making holes with hollow tines or a fork to decompact the soil; different from scarifying and sometimes done afterwards.
• Top dressing: a 0.5-1 cm layer of sand and sieved compost that levels, fills patches and makes a bed for new seed.
• Overseeding: spreading new seed over the scarified and top-dressed lawn to thicken it or fill patches.
• Starter fertiliser: a phosphorus-rich feed that stimulates seedling roots; applied 4-6 weeks after overseeding.
• Chafer grub: a "C"-shaped beetle larva that eats roots and makes the lawn lift in strips; treated with beneficial nematodes.

Frequently asked questions

Why is my lawn yellow if I water it a lot?

Watering a lot and often is usually part of the problem: it waterlogs, drives oxygen out of the root, washes out nitrogen and encourages fungi. Switch to long, spaced-out soaks, check that the water penetrates (if it sits on top, there's compaction or thatch) and feed. Too much water yellows a lawn as much as too little.

How do I fill the bare patches in the lawn?

Scratch the surface of the patch with a rake to loosen the soil, add a thin layer of top dressing (sand + compost), spread seed generously, cover it with a bit more top dressing, press with your foot and water. Keep it moist for 2-3 weeks. In autumn it germinates in 1-2 weeks.

What is scarifying and how often should I do it?

Scarifying is running vertical blades that pull out the "thatch", the layer of dead debris between the grass and the soil. It's done once a year (autumn or spring) on a normal lawn, or twice if it builds up a lot of thatch. Don't confuse it with aerating, which is making holes to decompact: they're different things and are sometimes done one after the other.

How do I fix the patches from dog urine?

Urine burns from excess nitrogen and salt. As soon as you see the dog has urinated, water that spot thoroughly with a watering can to dilute it. For patches already made: water the area a lot for several days to wash out the salt, scratch, top-dress and reseed. And train the dog to always use the same corner of gravel or bark.

Can I revive the lawn in summer?

Not with the full plan: scarifying and overseeding in summer is throwing away the work and the seed. In summer only first aid - raise the cutting height, water deeply at dawn, don't feed with nitrogen, treat root pests - and save the real recovery for September.

Is an electric scarifier worth it or will the manual one do?

For less than 100-150 m², the manual roller with tines does the job, though it's hard work. Beyond that, an electric scarifier (or the mower attachment) saves a lot of time and works more evenly. They're also hired out by the day.

What fertiliser do I use for a freshly overseeded lawn?

A starter one, with more phosphorus (P) than usual, which stimulates the root of the seedlings. Apply it 4-6 weeks after sowing, not before. The high-nitrogen fertiliser for "greening" is saved for when the new lawn has been mown two or three times.

Why is the lawn spongy and the water won't penetrate?

It's excess thatch: a layer of undecomposed stems and roots that acts like a waterproof sponge. The water sits on top or slides off. The solution is to scarify thoroughly and, if the soil is also hard underneath, aerate afterwards.

How long does a lawn take to recover?

One season. If you do the full plan in September, in 3-4 weeks the overseeding has germinated, in 2 months the lawn looks good and by spring it's dense. Damage from compaction or thatch takes longer to keep at bay: you have to maintain the annual aerating and scarifying.

What if the problem is the shade of a tree?

Under dense shade the lawn will never be perfect: it needs at least 3-4 hours of light. Prune the low branches so more light gets in, use a specific shade mix, mow higher (7-8 cm) and feed less. If it still doesn't thrive, consider replacing that area with shade-loving ground cover or decorative bark: it's in plants for every corner.

How do I revive a lawn scorched by summer sun and heat?

A lawn that's yellow from summer drought is almost always dormant, not dead: it regrows when the heat drops and water returns. In summer, raise the cutting height to 7-8 cm, water deeply at dawn and don't feed with nitrogen or scarify. Save the real recovery (scarify, top-dress, overseed) for September.

How often should you scarify and aerate a lawn?

Scarify once a year (twice if it builds up a lot of thatch), in autumn or spring. Aerate every 1-2 years if the soil compacts or there are high-traffic areas. They're not the same: scarifying pulls thatch off the surface, aerating decompacts deep down. When both are due, aerate after scarifying.

To avoid getting back to this point, keep the lawn up with how to care for a lawn: watering, mowing and feeding, and if you have to overseed a large area, with how to sow a lawn step by step.