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Lawn fertiliser UK: what to check before you buy

Updated: October 2026

You have a tired patch of lawn, and amazon.co.uk has piled a hose bottle, a 6-5-10 autumn bag and a weed-and-moss tub into one list for lawn fertiliser UK. Those packs do not do the same job. Check whether the grass needs feeding, then the season and the numbers, then the stated square metres, and only then whether a herbicide is in the box. Prices and stars for the seven saved listings sit on the [lawn fertiliser comparison](/hub/fertiliser-soil-and-bark-mulch/lawn-fertiliser). This decision order uses those listings and RHS guidance from 21 October 2026. It is not a turf trial.

You have a tired patch of lawn, and amazon.co.uk has piled a hose bottle, a 6-5-10 autumn bag and a weed-and-moss tub into one list for lawn fertiliser UK. Those packs do not do the same job.

Our top picks

Miracle-Gro Miracle-Gro Complete 4 in 1, 360 m²

Best overall

Miracle-Gro Miracle-Gro Complete 4 in 1, 360 m²
8.7/10about £24.94
View offer
A1Lawn A1 autumn winter fertiliser, 10 kg

Alternative

A1Lawn A1 autumn winter fertiliser, 10 kg
8.9/10about £34.20
View offer
Miracle-Gro Miracle-Gro Fast Green 1 litre

Rank 3

Miracle-Gro Miracle-Gro Fast Green 1 litre
9.0/10about £11.70
View offer
On this page
  1. 1.Feed only if the lawn is actually poor
  2. 2.Read the season and the three numbers before the brand
  3. 3.Match coverage to the lawn you measured
  4. 4.Say yes or no to a weed and moss claim

Feed only if the lawn is actually poor

The RHS says most lawns grow without feeding, and that you should feed only a poor lawn. A wildflower sward stays unfed. Drought-brown grass is often thirsty, not hungry. Feed when the sward is thin after you have checked shade, compaction and mowing height. Overfeeding scorches, so a large review file is not a reason to buy in October. Fast Green (B004RG2PD8, about £11.70) names no month or NPK on the Amazon bullets. The maker page states 27-0-0 with iron and March to September (Miracle-Gro Fast Green). Cite that page, not the saved listing.

Read the season and the three numbers before the brand

UK labels show nitrogen, phosphate as P2O5 and potash as K2O. A bigger first number pushes leaf. In this set, 6-5-10 is printed on A1 (B00MV0XMJI) and both Miracle-Gro autumn boxes. That is a different October job, not a weak feed. The RHS says not to use high-nitrogen feed after August. The Complete 4 in 1 listings say April to September on established lawns and print no NPK. A 1:0:0 mixing field is not an analysis. GreenCare prints 5 ml per litre for autumn and early winter, with no NPK. Use 35 g per square metre only where that listing prints it. The month split is on spring versus autumn lawn feed.
Miracle-Gro Miracle-Gro Complete 4 in 1, 360 m²

Testsieger

Miracle-Gro Miracle-Gro Complete 4 in 1, 360 m²
8.7/10about £24.94
View offer

Match coverage to the lawn you measured

Measure the grass, not the garden. A terrace lawn is often 60–80 m² once the patio and beds are out. Fast Green and A1 are about £0.12 per stated square metre. The 80 m² Complete is about £0.19. Both 360 m² packs are about £0.07, and the autumn one has two ratings. The 80 m² autumn box is about £0.15. GreenCare has no firm figure: 5 litres and up to 500 m² against a 10,000 ml unit count. At a printed 35 g per square metre, 80 m² needs about 2.8 kg. Do not paste that rate onto a listing that left it blank. Spreader steps are on how to apply lawn fertiliser.

Say yes or no to a weed and moss claim

Buy a herbicide only if the bullet names the weed. Only the two Complete 4 in 1 listings name dandelions, white clover and plantain, and they are for established lawns. The autumn boxes claim iron sulphate for moss and list no selective weeds. The 80 m² autumn box has five ratings at 3.8 stars, including a burnt lawn. A1 is iron-rich and is not sold as a moss killer. Fast Green and GreenCare claim neither. If you want named weeds, read weed and feed or a plain fertiliser.

Common questions

What do the three numbers on the bag mean?
They are the UK nutrient marks: nitrogen, phosphate as P2O5, and potash as K2O. Nitrogen feeds leafy growth. Phosphate and potash are the part of an autumn analysis sold for roots and harder growth. If the Amazon bullets do not print the three numbers, this comparison does not fill them in from another website. A mixing-ratio field is not an NPK.
Is 6-5-10 a weak feed because nitrogen is only 6?
No. In this set, 6-5-10 is the analysis printed on the A1 autumn and winter bag and on both Miracle-Gro autumn boxes. The lower first number is the point: it is not a spring growth feed. The RHS says not to use high-nitrogen lawn feed after August. A 6-5-10 bag in April is the wrong season, not a bargain version of a summer feed.
How do I match a pack to the square metres I measured?
Measure the grass, not the whole garden. Then use the coverage the listing states, and the gram rate only where that listing prints it. At 35 g per square metre, 80 m² needs about 2.8 kg, which matches the small autumn box and the small Complete tub. Do not copy 35 g per square metre onto Fast Green, the Complete 4 in 1 bullets, or the 360 m² autumn Amazon file, because those saved bullets do not print it.
Which of these listings include a weedkiller?
Only the two Miracle-Gro Complete 4 in 1 listings name weeds: dandelions, white clover and plantain, on established lawns from April to September. The autumn boxes claim iron sulphate for moss and do not list those weeds. A1, Fast Green and GreenCare do not claim weed control in the bullets. A feed-only bag will not kill dandelions just because the grass looks greener.
Why is there no firm price per square metre for the GreenCare bottle?
The bullets say 5 litres makes up to 1,000 litres and covers up to 500 m², and they also describe a 10 litre size. The unit count and liquid volume say 10,000 ml, and the item weight says 5 kg. Those fields disagree, so a price per square metre would be a guess. The shelf price on the saved listing is about £19.95, and there is one rating.
Can I treat a brand-new lawn with a 4-in-1?
The Complete 4 in 1 bullets say established lawns. A lawn sown this spring is outside that line. The maker’s autumn page says new lawns are treated only once established, usually after three months, which is a maker instruction for that autumn product, not a rule printed on every Amazon bullet here. Use a plain feed only if that pack’s own label allows a new sward.

Related pages

Best lawn fertiliser by job

Lawn fertiliser

How to apply lawn fertiliser without stripes or scorch

Spring vs autumn lawn fertiliser: which month fits

Weed and feed or lawn fertiliser: which box to buy

Sources

Public UK sources from the research digest, used for this page in October 2026. Prices, stars and review counts are the saved amazon.co.uk figures for the seven listings, not a live crawl on 21 October 2026. A score is stars plus review count, not a turf trial. Iron in a fertiliser is not an approved moss killer. A pet-return line is only what the bullets print.

  1. RHS, lawn care in spring and summer (retrieved 21 October 2026)
  2. RHS, lawn care in autumn (retrieved 21 October 2026)
  3. RHS, lawns in September (retrieved 21 October 2026)
  4. RHS, dead patches in lawns (retrieved 21 October 2026)
  5. RHS, moss in lawns (retrieved 21 October 2026)
  6. Fertilisers Regulations 1991 (retrieved 21 October 2026)
  7. GOV.UK, manufacturing and marketing fertilisers (retrieved 21 October 2026)
  8. HSE, pesticides in the garden and home (retrieved 21 October 2026)