Liquid fertiliser buying guide: job, dose, pack and where to use

Updated: October 2026

You have a watering can, a row of pots, and an amazon.co.uk page that mixes all-purpose concentrates with a seaweed tonic and an autumn lawn liquid.

You have a watering can, a row of pots, and an amazon.co.uk page that mixes all-purpose concentrates with a seaweed tonic and an autumn lawn liquid. A liquid fertiliser buying guide is the order of checks before you pay: the job, a dose you can follow, a pack that matches how often you mix, and where the label allows use. Stars and the cheapest litre do not decide that. The liquid fertiliser comparison holds the six kept prices from this capture. What follows is how to read those bottles, not a ranking. We compared amazon.co.uk listings and public UK sources. This is not a laboratory test.

Our top picks

Badge	Product	Stated job	Label rate	Where to use	Note	Price	Offer
Best overall	Invigortex GreenCare autumn lawn feed, 5 L	Autumn lawn liquid	5 ml per litre	Lawn grass	10.0	about £19.95	View offer
Best value	Doff Doff Liquid Growmore, 1 L	All-purpose liquid feed	1:466	Indoors, outside, greenhouse	9.6	about £6.55	View offer
Alternative	Maxicrop Maxicrop seaweed stimulant, 2.5 L	Seaweed growth stimulant	1:100	Home, garden, allotment	9.2	about £18.99	View offer

Best overall

Invigortex GreenCare autumn lawn feed, 5 L

10.0/10about £19.95

View offer

Best value

Doff Doff Liquid Growmore, 1 L

9.6/10about £6.55

View offer

Alternative

Maxicrop Maxicrop seaweed stimulant, 2.5 L

9.2/10about £18.99

View offer

On this page

1.Decide the job before the brand
2.Read the dose on the bottle you hold
3.Match pack size to how often you will mix
4.Check where the label allows use

Decide the job before the brand

Mixed pots and baskets want a declared NPK liquid on moist compost while the plant is growing. A seaweed stimulant sits beside that feed when you transplant or pot on cuttings. A September lawn wants a product labelled for autumn lawn use. Six listings cover three jobs. Doff 1 litre and the three Miracle-Gro All Purpose sizes are concentrates. Maxicrop 2.5 litres is a seaweed stimulant with Soil Association wording. GreenCare is an autumn lawn liquid. Turf stays with a lawn bottle. Conditional picks sit on best liquid fertiliser.

Read the dose on the bottle you hold

Cap size is not standard. Miracle-Gro says its cap has changed, so last year's one cap is unsafe. A mixing-ratio field is not an NPK analysis. Doff's field is 1:466. The brand page says 1 litre makes up to 300 litres, and Tanner Trading also prints 466 litres. Those figures are not reconciled. Use the measure on the bottle you hold. Miracle-Gro 1 litre prints 1:200. The twin 800 ml pack leaves the field blank. The 2.5 litre row prints 2:1:2, which is not a watering-can recipe. A brand PDF states 7-3-5 and half a cap per litre every 7 to 14 days. That PDF is a brand document. NPK is not on the stored listing. Maxicrop's field is 1:100, beside 45 ml in 9 litres (1:200). GreenCare prints 5 ml per litre, a lawn rate. If the bullets are almost empty, use how to use liquid fertiliser rather than a neighbour's capful.

Testsieger

Invigortex GreenCare autumn lawn feed, 5 L

10.0/10about £19.95

View offer

Match pack size to how often you will mix

These concentrates are used every one to two weeks in the growing season. A 2.5 litre bottle is the same product type as a 1 litre bottle. Capture prices run from Doff at about £6.55 and Miracle-Gro 1 litre at about £8.94 up to Miracle-Gro 2.5 litres at about £18.72, Maxicrop at about £18.99 and GreenCare at about £19.95. The twin 800 ml pack is about £7.98 and 1.6 litres in total. About £6.50 to £9 buys around a litre of all-purpose concentrate. Do not turn that into pence per watering without weighing the cap. One review says 800 ml arrived in a 1 litre bottle. Do not add the Miracle-Gro counts of 3,025, 10,350 and 72.

Check where the label allows use

Indoor, outdoor, edible and lawn are different lines. Doff names indoors, outside and the greenhouse. Miracle-Gro twin 800 ml and 1 litre name indoor use. Maxicrop names home, garden or allotment. The 2.5 litre Miracle-Gro indoor question is unanswered. GreenCare is lawn grass only. None of these listings is an ericaceous feed. Soil Association approval on Maxicrop allows organic growing. It does not supply a 7-3-5 analysis. GreenCare's title says 5 litres and the weight is 5 kg, while the volume fields say 10,000 ml. Do not buy that row for a windowsill.

Common questions

Do I need an NPK liquid, a seaweed tonic, or a lawn bottle?

Name the job first. Mixed pots and baskets want an all-purpose NPK concentrate such as Doff or Miracle-Gro in this set. A seaweed stimulant such as Maxicrop sits beside that feed for stress or organic systems. An autumn lawn liquid is only for turf. Stars do not merge those three jobs.

How do I read a mixing-ratio field that is not an NPK?

Treat 1:466, 1:200, 1:100 and 2:1:2 as listing fields, not analyses. NPK is not stated on any kept listing. Doff's model field is 7:7:7. Miracle-Gro's 7-3-5 sits on a brand PDF, not on the listing. If the field is not a can dose, read the bottle.

Why do Doff's 300 litres and the Amazon 1:466 field disagree?

The brand page says 1 litre makes up to 300 litres of feed. The amazon.co.uk mixing field is 1:466. Reviews quote one cap to 4.5 litres or half a cap in 5 litres. Those figures are copied side by side and are not reconciled. Use the measure on the bottle you hold.

Is a 2.5 litre bottle automatically better than 1 litre?

No. It is the same product type in a larger pack. The Miracle-Gro 2.5 litre row in this capture has almost empty bullets and a 2:1:2 field that is not a watering-can dose. Buy 2.5 litres only if you will mix through the season and already know the rate.

Which listings actually name houseplants versus lawn grass only?

Doff names indoors. Miracle-Gro twin 800 ml and 1 litre name indoor houseplants or indoor and outdoor use. Maxicrop names home and garden; reviews add indoor plants. The 2.5 litre Miracle-Gro indoor question is unanswered. GreenCare is lawn grass only.

Can I treat the three Miracle-Gro pack sizes as one review sample?

No. The twin 800 ml, 1 litre and 2.5 litre listings are separate captures with 3,025, 10,350 and 72 reviews. Do not add those counts. Live prices may differ from this snapshot.

When should I skip a listing with almost no bullets?

Skip it if you cannot read a dose, a target plant, or where to use it. That is the 2.5 litre Miracle-Gro problem in this file. A thin GreenCare review sample is a different skip: one incomplete United Kingdom text and an unresolved 5 litre versus 10,000 ml clash.

Liquid fertiliser for houseplants

Seaweed or liquid feed