Organic liquid fertiliser buying guide for UK pots

Updated: October 2026

You have a watering can, a crate of pots, and an amazon.co.uk page of brown bottles that all say organic.

You have a watering can, a crate of pots, and an amazon.co.uk page of brown bottles that all say organic. An organic liquid fertiliser buying guide is the order of checks before you pay: the job, a named control body if you need one, the dilution on that bottle, and a pack you can trust. Price and the word organic do not decide that. The organic liquid fertiliser comparison holds the nine kept prices from this capture. What follows is how to read those listings, not a ranking. We compared amazon.co.uk listings and public UK sources, and we did not run a laboratory test. A qualifying purchase can earn a commission at no extra cost to you.

Our top picks

Badge	Product	Role	Named control body	Dilution on the listing	Note	Price	Offer
Best overall	Sunshine Renewables UK Sunshine seaweed 2.5 L	Seaweed concentrate	Not named	1:200	10.0	about £16.99	View offer
Alternative	Topline Topline seaweed 2 x 1 L	Seaweed stimulant	Not named	1:10	9.6	about £16.99	View offer
Best value	Maxicrop Maxicrop seaweed 2.5 L	Seaweed stimulant	Soil Association	1:100	9.2	about £18.99	View offer

Best overall

Sunshine Renewables UK Sunshine seaweed 2.5 L

10.0/10about £16.99

View offer

Alternative

Topline Topline seaweed 2 x 1 L

9.6/10about £16.99

View offer

Best value

Maxicrop Maxicrop seaweed 2.5 L

9.2/10about £18.99

View offer

On this page

1.Start with the job, not the word organic
2.A named body only if you need the mark
3.A dilution you will not copy
4.Pack size and the star line

Start with the job, not the word organic

The first split is what you are trying to feed this month. Mixed pots, transplant shock, and a general tonic habit want a seaweed stimulant you dilute and pour onto moist compost. Fruiting tomatoes, peppers, chillies and aubergines want the tomato litre with the high-potassium highlight. A lawn wants the lawn litre on a 4-6 week interval, not a weekly pot habit copied onto turf. Chelated iron is only named on the Sunshine 6 L row. This capture keeps nine amazon.co.uk listings. Seven are seaweed stimulants, one is a lawn liquid, and one is a tomato liquid. Potting on cuttings in May is the stimulant aisle, and hungry crops still need a separate feed. The tonic-versus-feed argument sits on seaweed fertiliser or liquid feed. Conditional picks sit on best organic liquid fertiliser.

A named body only if you need the mark

The second check is whether the listing names a UK control body, and only if that mark is required. GOV.UK says calling food organic without a UK control body is illegal. An OF&G approved input may be used in an organic system without itself being organic food. Home gardeners who only wanted a brown bottle can skip the directory. Inspected growers cannot. A named body is not an NPK. Soil Association approval on Maxicrop Original means the stimulant may be used in an organic growing system. It does not mean the bottle supplies a tomato analysis.

Testsieger

Sunshine Renewables UK Sunshine seaweed 2.5 L

10.0/10about £16.99

View offer

A dilution you will not copy

The third check is the dilution on this label, not a neighbour's cap. Listed ratios in this set run from 1:10 on Topline to 1:500 on Shropshire. Maxicrop 2.5 L is 1:100 on Amazon and 1:200 on the maker Original label, 45 ml in 9 L. Those two figures stay side by side. This site does not reconcile them. Vitax has no mixing ratio in the attribute block. Copying 1:10 onto a 1:500 bottle is the usual way to scorch leaves or waste concentrate. The method sits on how to use organic liquid fertiliser.

Pack size and the star line

The fourth check is whether the pack on the page matches the bottle you expect. A rule of thumb for this shelf only: about £12 buys a 1 L crop bottle, about £17-£19 buys 2-2.5 L of general seaweed, and about £26-£41 buys 5-6 L. A 5 L at 1:500 is not the same buy as 2 x 1 L at 1:10. Vitax's title says 1 litre, while the item count and the volume field say 2 litres. Sunshine 2.5 L shows 5.0 from 5 reviews. Maxicrop 2.5 L shows 4.6 from 3,688. Those star lines are not one rank.

Common questions

What should I read first on an organic liquid listing?

Read the job first: stimulant, tomato feed, lawn feed, or seaweed plus iron. Then look for a named UK control body if you need one, then the dilution on that listing, then the pack size. Stars come last. A 5.0 from five reviews is not stronger evidence than 4.6 from thousands.

Does organic in the title mean it is certified?

No. Sunshine, Topline and Vitax titles say organic and do not name a control body in the captured bullets. Maxicrop 2.5 L names the Soil Association. Shropshire names OF&G. The lawn and tomato litres carry mixed strings. A title is not a certificate, and this site did not inspect a live directory listing.

Do I need a tomato bottle or a general seaweed?

If the plants are fruiting tomatoes, peppers, chillies or aubergines, the tomato litre is the feed-shaped bottle in this set. A general seaweed stimulant sits beside that feed. It does not replace it after fruit set. Mixed pots and transplant shock stay with a stimulant.

Why do dilutions differ so widely?

These nine listings are not one product. Topline prints 1:10. Maxicrop 2.5 L prints 1:100 on Amazon. Shropshire prints 1:500. Vitax prints none in the attributes. Use the bottle in your hand. Copying a neighbour's cap across brands is how leaves scorch or concentrate runs out in a week.

Is a 5 L always better value?

No. A 5 L at 1:500 is a different buy from 2 x 1 L at 1:10, and Shropshire at about £40.98 is not automatically better than Maxicrop 2.5 L at about £18.99. Compare the job and the printed ratio first. Then look at whether you will finish the bottle in one UK season.

Which bottles name Soil Association or OF&G?

Maxicrop 2.5 L names the Soil Association. Shropshire 5 L names OF&G. The Maxicrop lawn and tomato litres name OF&G on the bullet and the Soil Association on the highlight, without a certificate in the file. Sunshine, Topline and Vitax do not name a body.

Can I use this on a certified allotment?

Only if your inspector accepts the bottle as an approved input. Check the live Soil Association or OF&G directory for the product you hold. A title that says organic is not enough. Home gardeners who are not inspected can still use that check to avoid reading a title as a mark.

Soil Association organic liquid fertiliser