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Weed and feed or lawn fertiliser: which box you actually need

Updated: October 2026

Dandelions, moss in the shade and a patio you do not want stained are three different jobs. A 4 in 1 tub looks as if it does all of them. If the bullets do not name the weed, the pack will not kill it. If they do, you are holding a pesticide, and the label sets who stays off the grass. Prices and scores are on the [lawn fertiliser comparison](/hub/fertiliser-soil-and-bark-mulch/lawn-fertiliser). This uses the saved bullets, HSE garden-use pages and RHS guidance from 21 October 2026. It is not a turf trial.

Dandelions, moss in the shade and a patio you do not want stained are three different jobs. A 4 in 1 tub looks as if it does all of them. If the bullets do not name the weed, the pack will not kill it.

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.A feed and a weedkiller are different products even in one box
  2. 2.What the Complete 4 in 1 listings actually name
  3. 3.Iron, moss and the patio
  4. 4.When to leave the chemical out

A feed and a weedkiller are different products even in one box

A greener lawn is not a dead dandelion. Fast Green (about £11.70) claims neither weeds nor moss. GreenCare (about £19.95) is an autumn liquid at 5 ml per litre with no weed or moss claim. A1 (about £34.20) is 6-5-10 and iron-rich. It is not sold as a moss killer, and reviews say the moss stayed. Do not import a moss claim from another A1 size. Follow the label dose. Extra product can kill the lawn. Only two listings here print a pet-return sentence. Weed-and-feed is often unnecessary if you can live with clover. The month split is on spring versus autumn lawn feed.

What the Complete 4 in 1 listings actually name

B0G3PT35T9 and B0FZC3X2F1 name dandelions, white clover and plantain, claim moss control, and limit use to established lawns from April to September. Children and pets may return once the granules are watered in and dried. The 80 m² tub includes a handheld spreader. The 360 m² bag does not. One small-tub review waited five weeks with no weed kill. Horsetail is not on the list. New turf is outside established. There is no MAPP number in these Amazon files, so this page does not borrow one. Keep children and pets off until the lawn has dried. That sentence is not printed on the other five listings.
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

Iron, moss and the patio

Both Miracle-Gro autumn boxes claim iron sulphate to kill and control moss, with no selective weed list. The 80 m² pack (about £12.29) includes a spreader and a 35 g maximum. Five ratings average 3.8, including a burnt lawn and grass that died with the moss. Iron in a fertiliser is not, by itself, an approved moss killer. The maker page warns that iron sulphate stains clothing, tarmac, paving and decking (Miracle-Gro autumn lawn care). Those stain and pet lines are not on the saved Amazon bullets. Brush dry spills up. Do not wash them into a drain. Spreader steps are on how to apply lawn fertiliser.

When to leave the chemical out

Leave the chemical out when you can fork a few weeds, when the lawn is a wildflower mix, or when pets cannot stay off until the granules dry. A plain autumn 6-5-10 is A1, with moss control set to zero. Leave the 4-in-1 out on new turf or in October. Leave the autumn iron boxes out if you cannot spread evenly. If you accept the label, the Complete listings are the ones that name the weeds. The shortlist is on best lawn fertiliser by job.

Common questions

Which listings in this set actually name weeds?
B0G3PT35T9, the 80 m² Complete tub at about £15, and B0FZC3X2F1, the 360 m² Complete bag at about £24.94. Both name dandelions, white clover and plantain, claim moss control, and say April to September on established lawns. Horsetail is not on that list. No other listing in the seven prints a selective weed list.
When can children and pets go back on the grass?
On the two Complete listings, once the granules are watered in and the lawn has dried. That matches the HSE line to keep children and pets away until granules have been watered in. The maker’s autumn page says the same for that autumn product, but the saved Amazon bullets for the autumn boxes do not print it. Fast Green, A1 and GreenCare do not print a pet-return sentence. No listing here is pet safe as a logo.
Will iron sulphate mark the patio?
It can. The maker’s autumn page warns that iron sulphate stains clothing, tarmac, paving and decking. Ferrous sulphate moss and weed killers can mark concrete the same way. Brush granules off while they are dry. The Amazon bullets for the autumn boxes claim iron sulphate for moss and do not themselves print the stain warning, so treat the maker page as the maker page.
Can I use a 4-in-1 on a lawn sown this spring?
The Complete bullets say established lawns. A spring sowing is not that. Do not use those two listings on new turf. The maker’s autumn page says new lawns usually after about three months, which applies to that autumn product if you are following the maker, not to a six-month rule from a shop article. If you need a feed at all, it has to be a product whose own label allows new grass.
The moss went black and the grass went black too. What happened?
On the 80 m² autumn box, reviewers describe exactly that: grass dying with the moss, bald spots and nearly black patches, including one lawn that burnt when the instructions were followed. Stop. Do not put a second dose on the bald ground. Uneven spreading is described as difficult on that pack. Rake loose dead material later, and do not expect a feed-only bag to reverse a scorch.
Where must I not wash the granules?
Do not wash them into a drain, onto the patio, or into a bed. Brush dry spills up, including iron granules on paving. The HSE says extra product can kill the lawn and that you store the pack in its original container. A slope into a pond is a reason to stop and get advice rather than rinse the spreader out on the bank.

Related pages

Lawn fertiliser buying guide

Lawn fertiliser

Best lawn fertiliser UK: which pack fits your lawn

How to apply lawn fertiliser without stripes or scorch

Spring vs autumn lawn fertiliser: which month fits

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)