Feeding your lawn — when, how, and what

A handful of well-timed feeds a year does more for lawn health than weekly tinkering with extra products. The right product at the right time will out-perform a stronger one applied at the wrong time.

Why this matters

Grass is hungry. It pulls nitrogen, phosphorus and potassium out of the soil constantly to grow leaves, build roots and survive the seasons. Garden soils run out of these elements faster than most people think — especially nitrogen, which rains right through after a wet winter. A starved lawn turns yellow, thins out, and lets weeds and moss colonise the gaps.

Feeding isn't about pushing the lawn harder. It's about restoring what nature has already taken away.

When to do it

Four seasonal feeds cover the year. The first three are the workhorses; the late-autumn hardener is the finishing touch that lets the lawn ride out winter cleanly.

• Spring (Mar–May) — balanced NPK feed with moderate nitrogen to wake the lawn up. Wait until soil temperature is reliably above 8 °C and the grass has restarted growth.
• Summer (Jun–Aug, optional) — a low-nitrogen supplement only if growth has stalled in a wet, cool summer. Skip in heat — feeding stressed grass scorches it.
• Early autumn (Sep–Oct) — lower-nitrogen, higher-potassium feed that begins to harden the lawn against frost. Apply early enough that growth slows rather than restarts.
• Late autumn / early winter (late Oct–Dec) — zero-nitrogen, very high potassium hardener with iron and seaweed. It's not a growth feed; it strengthens cell walls and root reserves so the lawn comes through frost, disease and waterlogging in better shape. Apply on a dry, mild day before the ground freezes.

The engine waits for daytime temperatures averaging 10 °C or higher over five days for the spring/summer/early-autumn feeds, with rain or irrigation due within 48 hours to wash the granules in. The late-autumn hardener tolerates cooler ground (down to ~5 °C) — it isn't pushing growth.

When not to feed

• Within a day of mowing. Fresh-cut leaf tips are open wounds; let the lawn close before exposing it to fertiliser.
• On wet grass. Granules clump on damp leaves and scorch the spots they sit on.
• With heavy rain forecast in the next 24 hours. The feed runs off before it dissolves.
• Drought or heatwave. Feeding a stressed lawn burns it within days.
• Below ~6 °C average for a growth feed. Grass is dormant; nitrogen sits unused and fertilises weeds instead. The late-autumn hardener is the exception — it's designed for cooler ground and isn't pushing growth.
• A previous feed is still active. Most granular feeds work for 6–12 weeks (the bag tells you). Stacking doses risks scorch.
• Within 6 weeks of seeding. Seedlings need a starter feed (low-N, high-P), not regular lawn feed — full-strength burns them.
• Within a week of scarifying or weed treatment. Don't stack stresses.

How to do it

1. Match the product to the season. Higher-N balanced feed in spring, lower-N supplement in summer if needed, lower-N higher-K feed for early autumn, and a zero-N high-K hardener for late autumn / early winter. Reading the bag's NPK is more reliable than the marketing on the front.
2. Mow 1–2 days before. Even surface, fresh growth that's settled.
3. Apply when the grass is dry. Use a spreader, not a hand-throw. Hand-scattering produces stripes and burnt patches.
4. Calibrate the spreader. Halve the manufacturer's rate and double-pass at right angles for even coverage. Saves over-application in any one spot.
5. Water it in within 24–48 hours. If rain isn't on the way, run a sprinkler. The granules need to dissolve and reach the roots; sitting on the surface they degrade in sun.
6. Don't double-apply if you missed a strip. Over-feed scorches far worse than under-feed. Mark the missed strip and pick it up next time.

What to expect afterwards

A good feed shows results in 7–14 days. The lawn deepens in colour first — a richer green that catches the light differently. Growth picks up; you'll be mowing more often within two weeks. The texture thickens slightly as side-shoots come through.

If you see a uniform yellow or brown cast a few days after feeding — and you applied it on dry grass at the right rate — you may have hit a heatwave. Water in well and the lawn usually recovers in 2–3 weeks.

If you see stripes or patches of dark green and pale green, the spreader was uneven. Live with it for the season; the next mow rotation evens it out.

Common mistakes

• Feeding through a heatwave. Visible burning within days. Wait.
• Granules on wet grass. They stick and scorch in patches. Always let the leaf dry.
• High-nitrogen feed in autumn. Pushes soft growth that frost damages. The "winter feed" formulations are intentionally low-N.
• Feeding new seedlings with regular lawn feed. Burns them. Use a starter feed (sometimes labelled "new lawn feed") during the first 6 weeks.
• Eyeballing the rate. Most lawn problems traced back to feed are about over-application. The bag's rate per square metre is a hard cap, not a starting point.

Seasonal notes

Spring: first feed of the year typically lands in late March or April, depending on how mild the spring is. Don't rush — temperature matters more than the calendar.

Summer: optional. If using, low-N only and a slow-release product is friendlier than a fast one. Skip if there's been any drought.

Autumn: the most under-rated feed of the year. The September early-autumn application starts the hardening process; a late-autumn hardener (zero-N, high-K) goes on top in late October or November before the ground freezes.

Winter: no growth feed. The late-autumn hardener can extend into a mild December if you missed the November window — pick a dry, frost-free day above ~5 °C. Otherwise leave the lawn alone.

What should I feed my lawn with?

A small number of well-timed seasonal feeds beats constant tinkering. A subscription plan posts the right feed at the right time, or pick the single seasonal bag you need now.

Related Mowd guides: UK Lawn Care Calendar · Summer lawn feed & wetting agent

Frequently asked questions

How often should I feed my lawn?

Three to four times a year is plenty: a spring feed, an optional light summer feed, an early-autumn feed and a late-autumn hardener. Timing matters more than quantity.

Can I feed my lawn in summer?

Only lightly, and only if growth has stalled in a cool, wet spell. Never feed stressed grass in a heatwave — it can scorch.

What happens if I do not feed my lawn?

It slowly thins, yellows and loses colour, and the bare gaps let moss and weeds move in. Feeding simply replaces the nutrients the grass and rain remove.

Disclaimer

This is a general guide for typical UK domestic lawns. It doesn't cover every grass mix, soil type, climate quirk, or specialty product. New lawns, recently renovated lawns, and lawns with persistent yellowing or moss problems benefit from a soil test before feeding — guess less, fix more.