Nitrogen fertiliser for lawns, and the months that matter

Updated: October 2026

A pale lawn in April feels like a reason to buy a high-nitrogen bag. Sometimes the grass is dry, or it is a mixed sward you should not feed.

A pale lawn in April feels like a reason to buy a high-nitrogen bag. Sometimes the grass is dry, or it is a mixed sward you should not feed. Nitrogen fertiliser for lawns is a spring decision: denser grass while it is growing, and not a leftover summer feed in October. The lawn granules in the nitrogen fertiliser comparison are the two Bottos Sprint N packs. Vegetables and hydroponic bottles belong on other pages. Prices are amazon.co.uk figures from 19 October 2026. This page is from Peter F., the DIY and tools editor, set against RHS lawn pages. This is not a lab test. A qualifying purchase can earn a commission at no extra cost to you.

Our top picks

Badge	Product	Nitrogen on the listing	Months named	Stated cover	Note	Price	Offer
Best overall	Hesi Hesi TNT Complex, 500 ml	Model line N P K 3-2-3	Not stated	Not on the listing	6.8	about £14.28	View offer
Best value	Bottos Bottos Sprint N, 2 kg	Title 27-5-15; bullets 27-0-14	February to May, then August to October	2 kg per 80 m²	8.4	about £13.87	View offer
	Bottos Bottos Sprint N, 4 kg kit	27-0-14 on the model and the bullets	February to May, then August to October	4 kg per 160 m²	8.6	about £29.01	View offer

Best overall

Hesi Hesi TNT Complex, 500 ml

6.8/10about £14.28

View offer

Best value

Bottos Bottos Sprint N, 2 kg

8.4/10about £13.87

View offer

Rank 3

Bottos Bottos Sprint N, 4 kg kit

8.6/10about £29.01

View offer

On this page

1.Whether this lawn needs nitrogen
2.The spring and summer window
3.What to do with September and October on the bag
4.Autumn is a different feed
5.A house lawn, a pitch, or a field

Whether this lawn needs nitrogen

The RHS says most lawns grow without feed. A wildflower lawn should not be fed, because extra nitrogen favours grasses over the flowers. Brown grass in a dry spell is often drought, not hunger, and nitrogen will not solve moss by itself. Feed if you want a denser, all-grass lawn and the turf is growing. If the lawn still looks poor after a sensible spring feed, the RHS allows another application, inside the limit below. A pitch or a large paddock needs a turf adviser before you scale a domestic bag. Weighing, once you have decided to feed, is on how to use nitrogen fertiliser.

The spring and summer window

Use a spring and summer lawn fertiliser, high in nitrogen, in mid-spring while the grass is growing. The RHS puts that at usually late March to April. Do not push nitrogen beyond August. A second RHS page says do not fertilise after September, and it names high-nitrogen lawn fertilisers. Those are two sentences, not one date. Do not collapse them into early autumn and then feed in October. Scotland and northern England start autumn lawn work in September. The October notes still say not to use leftover summer feed.

Testsieger

Hesi Hesi TNT Complex, 500 ml

6.8/10about £14.28

View offer

What to do with September and October on the bag

Bottos bullets name February, March, April, May, August, September and October. The listing is describing its own months. It is not a licence to ignore the August limit. The 4 kg pack agrees on 27-0-14. The 2 kg title prints 27-5-15 while the bullets print 27-0-14. A 60–90 day claim was not measured here, and it is not a reason to apply in September. Red thread is sometimes treated with sulphate of ammonia, which is not in this set. Which NPK you bought is on the nitrogen fertiliser buying guide.

Autumn is a different feed

Most lawns recover without an autumn feed, the RHS says. If you do feed, use an autumn formulation. Retail autumn products are described as potassium-led, with examples such as 4-0-8 or 3-4-12 that are not these ASINs. A 27-0-14 analysis stays nitrogen-led. The last figure does not turn it into an autumn feed while the first figure is 27. Slow-release wording on the 4 kg title does not change the NPK. Which spring pack to choose is on best nitrogen fertiliser. Hesi, VegAzoto, UK Grow and Vitax are not this calendar.

A house lawn, a pitch, or a field

A domestic lawn is outside the English nitrate vulnerable zone closed period. On agricultural grassland that period runs from 15 September to 15 January, with a grass exception of up to 80 kg of nitrogen per hectare, no more than 40 kg at once, and none after 31 October. Do not copy that hectare maths onto a garden. Someone farming uses the GOV.UK map, a FACTS adviser, or RB209. These packs do not name ammonium nitrate, so a 2 kg lawn bag is not shown as that regulated precursor.

Common questions

Does a UK lawn need nitrogen fertiliser?

Most lawns grow without it, according to the RHS. Feed if you want denser grass-only turf and the grass is growing. Do not feed a wildflower lawn. Pale or mossy grass after a dry spell is often drought rather than a nitrogen shortage. A bag is a choice about thickness, not a default for every garden.

When should a high-nitrogen lawn feed go on, and when must it stop?

In mid-spring, usually late March to April, while the grass is growing. A second application is only if the lawn still looks poor. Do not push nitrogen beyond August. A separate RHS page says do not fertilise after September, including high-nitrogen lawn feeds. Keep both sentences. Neither is permission for October. February on a bullet list is earlier than the usual window.

Why do Bottos bullets name September and October?

The bullets list February through May, then August, September and October, beside a high-nitrogen analysis and an unmeasured 60–90 day claim. The RHS spring page says not beyond August, and the autumn pages say not to use leftover summer feed. Quote both. Do not treat the bullet list as the UK calendar.

Is 27-0-14 an autumn lawn feed?

No. Autumn products are described as lower in nitrogen and richer in potassium. Shop examples such as 4-0-8 are not these ASINs, and most lawns recover without an autumn feed. A 27-0-14 granule is a spring-style analysis, whether or not the listing says slow-release.

Is a house lawn inside a nitrate vulnerable zone closed period?

The closed period on GOV.UK is for agricultural grassland, from 15 September to 15 January, with a limited exception in kilograms per hectare. A house lawn is outside that wording. If you farm the land, use the GOV.UK map and a FACTS adviser or RB209. A pitch or large paddock needs a turf adviser, not a domestic coverage sum stretched across the field.

Will nitrogen stop moss and weeds?

The RHS points to drought more than hunger when weeds and moss increase. Nitrogen is for leaf growth on a lawn you have already decided should be dense grass. It is not a moss killer. Watering and mowing in a dry summer matter more than another pass with a spring bag after August.

Liquid or granule nitrogen fertiliser