How do I repair a lawn after a drought?

Every hot summer produces a wave of people reseeding in August, watering it daily, and losing both the seed and the money. Grass recovers from drought extremely well if left alone, and the window for repair is autumn, not the tail of the heat. The useful skill here is telling dormant grass from dead grass, and then waiting for the right month.

Step by step

1. Establish whether it is dormant or dead.Dormant grass is straw-coloured but the crowns at soil level are still firm and the plant is intact — tug a handful and it resists. Dead grass pulls away easily with no resistance and the crown is dry and brittle. Look also at whether it is uniform: a whole lawn browning evenly is dormancy, while scattered dead patches in an otherwise green lawn suggest something else, such as chafer grubs, disease or dog urine.
2. Do nothing at all during the drought.No mowing to speak of, no feeding, no weedkiller, no seed, no scarifying. Dormant grass is surviving on stored reserves and every one of those operations spends reserves it does not have. Keep off it as much as you can, since traffic on dormant grass damages crowns that would otherwise recover.
3. Wait two to three weeks after real rain before judging anything.Recovery is not immediate. Green appears first at the base and spreads up, and a lawn that looked finished in August is routinely green again in late September. Anything you decide before then, you will probably decide wrongly.
4. Resist the urge to feed the moment it rains.A high-nitrogen feed onto stressed grass forces top growth the root system cannot support, and in warm damp conditions it invites disease. If you feed at all, use an autumn feed, which is lower in nitrogen and higher in potassium, and apply it when the grass is already growing again.
5. Do the real work in early autumn.Early autumn is the ideal window in the UK: soil still warm enough for fast germination, reliable moisture, weaker weed competition, and months of mild growing weather ahead. This is when scarifying, aerating, overseeding and top-dressing all succeed with the least effort.
6. Scarify to remove the dead material.Drought leaves a mat of dead grass and thatch that stops seed reaching soil and stops water penetrating. Rake it out vigorously with a spring-tine rake or a powered scarifier. It will look far worse before it looks better — that is normal and necessary.
7. Aerate if the soil is compacted.A summer of dry, hard ground and foot traffic compacts soil, and compacted soil sheds water rather than absorbing it, which sets up the same problem next year. Hollow-tine aeration is best; a garden fork pushed in and rocked at intervals is a fair substitute on a small lawn.
8. Overseed the bare areas.Rake the surface to a fine tilth, sow a seed mixture suited to the lawn and its use, rake lightly to make contact, and firm it. Seed-to-soil contact is what decides germination, far more than the amount of seed. Keep it moist until established — in autumn that usually means the weather does it for you.
9. Top-dress to level and improve.A thin layer of sandy loam or a proprietary top-dressing brushed into the surface fills hollows, improves the seedbed and helps with the compaction. Keep it thin enough that grass tips still show through.
10. Change something for next year.The lawns that suffer worst are the ones cut shortest. Raising the mowing height, aerating annually and accepting a browner lawn in August are what stop this recurring. A lawn cut long shades its own roots and holds moisture far better.

Tips

• The parts that stay brown longest are usually the shallowest soil — over a buried path, a builder's rubble patch, or a dry strip along a wall. That is a soil depth problem and no amount of seed fixes it without adding soil.
• If you are going to water a lawn at all, water deeply and rarely, which encourages deep rooting. Frequent light watering produces shallow roots and a lawn that fails faster next time.
• Do not lay new turf in high summer. It needs constant water to establish, and autumn turf takes with a fraction of the effort.
• A drought-damaged lawn is an opportunity to overseed with a more drought-tolerant mixture containing fescues, which cope far better than the ryegrass in cheap seed.
• Clover in a lawn stays green through drought long after grass has browned. Many people now deliberately include it rather than treating it as a weed.

Common mistakes

• Reseeding in August while it is still hot and dry — Seed needs consistent moisture to germinate and establish. Sown into hot dry soil it either fails to germinate or germinates and dies, and the money is gone. Autumn does the same job with far less watering.
• Feeding a stressed lawn to green it up — Nitrogen forces top growth that the drought-weakened roots cannot support, and encourages disease. Feed when it is already growing, and use an autumn formulation.
• Scarifying in the middle of a hot spell — It tears out living material from a lawn that is already surviving on reserves, and exposes soil to further drying. It is an autumn job.
• Digging up and re-turfing a brown lawn — Most of it is dormant and will recover for free. Waiting three weeks after rain costs nothing and usually removes the need entirely.

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