How much lawn feed do I need per square metre?

Most UK lawn feeds recommend an application rate of approximately 35 grams per square metre (35g/m²). This is equivalent to a small handful per square metre. A standard 3.5kg box covers about 100m², and a 7kg box covers about 200m². Always check the specific product instructions as rates can vary between brands.

When should I feed my lawn in the UK?

Feed your lawn three times per year for the best results. Apply spring feed (high nitrogen) in March to May for green-up and strong growth. Use summer feed in June to August to maintain health during hot weather. Apply autumn feed (high potassium) in September to November to build root strength and winter hardiness. Weed & Feed products are best applied April to September.

Is it better to use a lawn spreader or apply by hand?

A lawn spreader gives much more even coverage and is strongly recommended for areas over 50m². Hand application tends to be uneven, leading to stripy results — dark green patches where too much was applied and pale patches where it was missed. If applying by hand, split the product into two halves and apply in perpendicular directions for more even coverage.

Can I apply too much lawn feed?

Yes, over-application (known as fertiliser burn or scorching) is a common mistake. It causes yellow or brown patches and can kill the grass. Always follow the recommended application rate of 35g/m². If you are unsure, it is better to apply slightly less than too much. Water well after application if no rain is forecast within 48 hours.

Should I water after applying lawn feed?

Ideally, apply lawn feed when rain is forecast within 24-48 hours, or water the lawn lightly after application. This helps the granules dissolve and reach the roots. Do not apply in drought conditions or when the grass is dormant. For weed & feed products, you need the leaves to be damp for the weed killer to stick — apply when dew is on the lawn.

TradeCalcs

Lawn Feed Calculator — How Much Lawn Feed Do I Need?

Calculate the right amount of lawn feed, weed and feed, or seasonal fertiliser for your lawn area. UK application rates.

Lawn Length

Length of your lawn

Lawn Width

Width of your lawn

Product Type

March-May — High nitrogen for green-up and growth

Application Method

Even coverage recommended

Price Per Box (optional)

Enter your supplier price for a cost estimate

How We Calculate This

Our lawn feed calculator multiplies your lawn area by the standard application rate to work out how much product you need, then converts this to the number of boxes or bags required.

The formula

Lawn area = Length × Width

Product needed (g) = Area (m²) × Application rate (g/m²)

Boxes = Area ÷ Box coverage (rounded up)

Application rates

Spring feed: ~35 g/m² (high nitrogen N:P:K)
Summer feed: ~35 g/m² (balanced N:P:K)
Autumn feed: ~35 g/m² (high potassium N:P:K)
Weed & Feed: ~35 g/m² (combined herbicide + feed)

Standard box sizes

Small box: 3.5 kg — covers approx. 100 m²
Large box: 7 kg — covers approx. 200 m²

Always check the specific product instructions as rates and coverage may vary between manufacturers. Our calculator uses the most common UK application rates as a guide.

Frequently Asked Questions

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Last updated: February 2026

All calculations are estimates. Verify with your supplier.