How and when should I feed a lawn?

Spring and autumn feeds do different jobs, applying evenly without stripes, and why more is worse.

Difficulty: beginner
Time: 1 hr
Read: 3 min
Safety: caution

Short answer

A high-nitrogen feed in spring for growth and colour, and a high-potassium autumn feed for root strength and winter hardiness. Apply evenly with a spreader and water it in unless rain is due.

Lawn feeding fails in two ways — the wrong feed at the wrong time, and uneven application that leaves the lawn striped for months.

Safety

Lawn feed is concentrated fertiliser and scorches grass badly if over-applied or applied to a dry lawn. Keep pets and children off treated grass until it has been watered in. Never let lawn feed wash into a pond, where the nutrients cause algal blooms that kill fish.

What you'll need

A drop or rotary spreader
Spring or autumn lawn feed as appropriate
A hose, if no rain is forecast

Step by step

Use a spring feed for growth.High in nitrogen, applied from around April once the grass is actively growing. It drives leaf growth and colour through the main season.
Use an autumn feed for roots.Low nitrogen, high potassium and phosphorus, applied September or October. It hardens the grass for winter rather than pushing soft growth that will be damaged by frost.
Never use spring feed in autumn.High nitrogen late in the season produces soft growth that is vulnerable to frost and disease. It is a common and damaging error.
Mow a few days before.Feed reaches the soil better on a recently cut lawn, and you can see your application pattern more clearly.
Apply to a moist lawn.Fertiliser on dry, stressed grass scorches. Apply after rain or water the lawn first, then water the feed in.
Use a spreader, not your hand.Hand scattering always produces dark green patches and pale stripes that persist for months. A spreader is inexpensive and the difference is obvious.
Apply half in each direction.Half the dose walking north-south and half east-west. It evens out any inconsistency in the spreader and eliminates stripes.
Water it in.Unless rain is forecast within a day. Granules sitting on dry leaf blades scorch them, and the feed does nothing until it reaches the soil.
Do not exceed the dose.More is not better — excess nitrogen scorches, encourages disease and leaches into watercourses. Follow the stated rate exactly.
Consider a combined product carefully.Feed, weed and moss killer products work but apply herbicide to the whole lawn. If weeds are localised, feed separately and spot-treat.
Test the soil if results are poor.A cheap pH kit. Grass prefers slightly acidic soil around 6 to 7, and very acidic or alkaline soil limits nutrient uptake whatever you apply.

Tips

Spring feed for growth, autumn feed for roots. Using them the wrong way round causes real damage.
Half the dose in each direction with a spreader. It is the only way to avoid stripes.
Water it in unless rain is due, or the granules scorch the leaf.

Common mistakes

Applying high-nitrogen feed in autumn — It forces soft leafy growth just as the grass should be hardening off, leaving it vulnerable to frost damage and fungal disease over winter.
Scattering feed by hand — Human distribution is far less even than it feels, and the result is a permanently striped and patchy lawn for the rest of the season.

If it doesn't work

Dark green stripes on the lawn

Cause: Uneven application — Fix: Nothing quick — it grows out over weeks. Use a spreader and apply half the dose in each direction next time.

Scorched yellow patches

Cause: Over-application or feed on dry grass — Fix: Water heavily to dilute. Badly scorched areas need reseeding.

No response to feeding

Cause: Compaction, shade, or soil pH — Fix: Aerate, test the pH, and consider whether the area gets enough light for grass.

Lawn lush but full of moss

Cause: Feeding without addressing drainage and shade — Fix: Aerate and scarify. Moss is a symptom of conditions rather than a lack of feed.

Questions people ask

How often should I feed a lawn?

Twice a year is enough for most domestic lawns — a spring feed and an autumn feed. Heavily used or ornamental lawns may take a third summer application.

Can I use spring feed all year?

No. Its high nitrogen content is wrong for autumn, where it produces soft growth that suffers in frost. Autumn feeds are formulated with potassium for hardiness instead.

Do I need a spreader?

It makes a substantial difference. Hand application is never even enough and the resulting stripes last for months, which is far more visible than people expect.