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How to use nitrogen fertiliser without guessing the rate

Updated: October 2026

The pack is in the shed and the lawn or the can is waiting. A handful, or a splash, is not a dose. How to use nitrogen fertiliser starts with the rate printed for the pack in your hand. If two rates disagree, or the dose is missing, you stop. You do not invent one. Listings are on the [nitrogen fertiliser comparison](/hub/fertiliser-soil-and-bark-mulch/nitrogen-fertiliser). Prices, where they appear, are the 19 October 2026 amazon.co.uk snapshot. This page is from Peter F., the DIY and tools editor, using those listings and RHS notes on scorch. This is not a lab test. A qualifying purchase can earn a commission at no extra cost to you.

The pack is in the shed and the lawn or the can is waiting. A handful, or a splash, is not a dose. How to use nitrogen fertiliser starts with the rate printed for the pack in your hand.

Our top picks

Bottos Bottos Sprint N, 2 kg

Best overall

Bottos Bottos Sprint N, 2 kg
8.4/10about £13.87
View offer
Bottos Bottos Sprint N, 4 kg kit

Rank 2

Bottos Bottos Sprint N, 4 kg kit
8.6/10about £29.01
View offer
McMillan VegAzoto nitrogen liquid, 1 litre

Alternative

McMillan VegAzoto nitrogen liquid, 1 litre
3.6/10about £18.99
View offer
On this page
  1. 1.Weigh the granule rate you can defend
  2. 2.Spread it evenly and water it in
  3. 3.Dilute only in the units on the label
  4. 4.When there is no dose
  5. 5.Scorch, pets, and a dead patch

Weigh the granule rate you can defend

Bottos states coverage, not the words 25 g per square metre. Dividing 2 kg by 80 square metres, or 4 kg by 160, implies 25 g. That figure is not a separate printed instruction. A review mentions 30–35 g. Do not average the two. Weighing does not settle which analysis is in the bag. That check is on the nitrogen fertiliser buying guide. Measure the lawn in metres, then weigh the total before you walk on the grass.

Spread it evenly and water it in

Weigh the total off the lawn. A spreader setting is a guide, not the dose. Split the granules into two passes, one up and down and one across, and brush them off paths. The RHS says to water in if rain is not forecast. Italian reviews describe burnt patches when granules sat in warm weather, and one note says granules had not dissolved after a week of rain. Whether you should feed at all is on nitrogen fertiliser for lawns.
Bottos Bottos Sprint N, 2 kg

Testsieger

Bottos Bottos Sprint N, 2 kg
8.4/10about £13.87
View offer

Dilute only in the units on the label

A liquid that prints millilitres per litre scales by proportion. VegAzoto prints 300–500 g per 100 litres, so a 10 litre can is 30–50 g and a 5 litre can is 15–25 g. It is still grams. The listings do not give a density, so they do not support a syringe mark. Weigh the liquid, and start at the lower end if you have not used it. Hesi is a different case: the amazon fields have no dose. Do not mix that silence up with VegAzoto's gram line.

When there is no dose

UK Grow and Vitax print no dilution. The Hesi listing prints 3-2-3 and no dose. Do not copy a lawn gram rate onto a bottle. The Hesi maker's page, which is not the amazon field set, says 50 ml per 10 litres for soil and coco. A review says 2 ml per litre. Do not apply the maker's figure to UK Grow or Vitax. If the label in your hand is blank, leave the product unused. The form you should have bought is on liquid or granular nitrogen fertiliser.

Scorch, pets, and a dead patch

Brown stripes after feeding usually mean an overdose or a spreader that dumped one pass. Water the area if granules are still visible. Do not follow a stripe with a stronger feed. No statute in these sources sets a pet waiting time, and none of these packs is shown to be safe for pets. Keep animals off until the granules are watered in and the grass is dry. A pitch, a paddock, or farmland is outside a watering-can method. Use a FACTS adviser or RB209 for that land.

Common questions

How do you turn 2 kg per 80 square metres into grams?
Two kilograms is 2,000 g, and 2,000 divided by 80 is 25 g per square metre. The 4 kg claim for 160 square metres is the same sum. Call it the figure implied by the coverage line, not a printed 25 g instruction. Forty square metres at that rate is 1,000 g. Weigh it before you spread.
Why not use 30–35 g per square metre from a review?
Because it is not the coverage line. A review and an Italian shop mention 30–35 g. The bullets imply 25 g if you divide 2 kg by 80 square metres. Averaging them invents a third rate. If the tub shows one figure, follow the tub. If it shows neither, do not upgrade the dose because a review sounded greener.
How do you spread granules without leaving a stripe?
Weigh the dose off the grass, then walk it on in two directions, about half each way, at a steady pace. Treat the hopper setting as a guide. Brush granules off paths. A single heavy pass along the same line is how brown stripes show up later.
When do you water it in, and what if the bottle has no dose?
Water granules in if rain is not forecast. Italian reviews on these Bottos listings describe burn when granules sat in warm, dry weather. If the bottle prints no dose, do not borrow one. UK Grow and Vitax have none. Hesi's listing has none. The maker's 50 ml per 10 litres is a separate Hesi page, and a review's 2 ml per litre is a third statement. None of those belongs on the other products.
How do you scale 300–500 g per 100 litres?
A 10 litre can is a tenth of 100 litres, so the range is 30–50 g. A 5 litre can is 15–25 g. You are still weighing grams. The listings give no density, so they do not support a millilitre mark. Start at the lower end of the range if the liquid is new to you.
How long should pets stay off, and what about a burnt stripe?
These sources set no legal hour count and do not show these packs are safe for pets. Keep animals off granules until they are watered in and the grass is dry. That is a precaution, not a tested interval. Water a stripe if fertiliser is still sitting there, and do not follow it with a stronger bag. If the patch is dead weeks later, plan to reseed.

Related pages

Best nitrogen fertiliser

Nitrogen fertiliser

What a nitrogen fertiliser label must show before you buy

Nitrogen fertiliser for lawns, and the months that matter

Liquid or granular nitrogen fertiliser for the job

Sources

Public UK sources from the research digest, used for this page in October 2026. Prices, stars and review counts are from the seven amazon.co.uk listings captured on 19 October 2026. A 60–90 day release claim was not measured. These listings do not name ammonium nitrate. A domestic lawn is outside the English nitrate vulnerable zone closed period.

  1. RHS, Lawn care in spring and summer (retrieved 19 October 2026)
  2. RHS, Fertiliser labels explained (retrieved 19 October 2026)
  3. RHS, Fertilisers: types and uses (retrieved 19 October 2026)
  4. RHS, Lawns: dead patches (retrieved 19 October 2026)
  5. GOV.UK, Supplying explosives precursors and poisons (retrieved 19 October 2026)
  6. GOV.UK, Using nitrogen fertilisers in nitrate vulnerable zones (retrieved 19 October 2026)
  7. GOV.UK, Rules for farmers and land managers to prevent water pollution (retrieved 19 October 2026)
  8. BBC Gardeners' World, Understanding and using NPK fertiliser (retrieved 19 October 2026)