Hydrangea fertiliser buying guide: feed, colour or none

Updated: October 2026

You have a hydrangea that flowered last July, and the amazon.co.uk shelf is offering a liquid, a bag of granules, and a tub that promises blue.

You have a hydrangea that flowered last July, and the amazon.co.uk shelf is offering a liquid, a bag of granules, and a tub that promises blue. This hydrangea fertiliser buying guide is the choice before the basket: a nutrient feed, a colourant, both, or nothing. The hydrangea fertiliser comparison lines up the ten listings we kept. Prices and star lines are the amazon.co.uk captures from 19 October 2026, not a live recrawl. We did not run a lab trial. A qualifying purchase can earn a commission at no extra cost to you.

Our top picks

Badge	Product	Job	Form	Colour claim	Note	Price	Offer
Best overall	Topline Topline bundle: Westland liquid feed 1 litre and colourant 500 g	Feed plus colourant	Granules, liquid	Pink to blue	9.0	about £16.99	View offer
	Vitax Ltd Vitax hydrangea feed granules, 2 x 1 kg	Granular feed	Granules	No pink-to-blue	9.8	about £11.98	View offer
Best value	Westland Westland hydrangea colourant, 500 g	Colourant	Liquid	Pale pink to blue	9.4	about £6.99	View offer

Best overall

Topline Topline bundle: Westland liquid feed 1 litre and colourant 500 g

9.0/10about £16.99

View offer

Rank 2

Vitax Ltd Vitax hydrangea feed granules, 2 x 1 kg

9.8/10about £11.98

View offer

Best value

Westland Westland hydrangea colourant, 500 g

9.4/10about £6.99

View offer

On this page

1.When you do not need a hydrangea fertiliser
2.Feed, colourant, or a bundle
3.Plant and place before the pack
4.What to check on the label

When you do not need a hydrangea fertiliser

The Royal Horticultural Society says regular feeding is not generally needed. On a lot of borders the real problem is drought. A mature mophead that already flowers does not need a liquid every seven days. Struggling plants on lighter soil may justify a spring feed. If last year’s stems are long and soft, another round of feed is the wrong correction. A pot in tired compost, with pale leaves, is a measured spring dose. The best hydrangea fertiliser page matches a pack to that job.

Feed, colourant, or a bundle

The ten listings split into three purchases, and they are not substitutes. A feed is nutrients: Vitax granules, two 1 kg bags at £11.98 (4.4 from 1,741 reviews); Topline liquid, two 1 litre bottles at £16.99 (4.7 from 68); Neudorff Azet 1 kg at £12.99, with four reviews marked Spain and no certifier. The Vitax powder titled 1KG (6) at £39.29 has a unit count of 1000 gram. Do not read that title as six kilograms. A colourant is a salt for flower colour, not a complete feed. Under about £9: Westland 500 g at £6.99 (4.2 from 1,244), Vitax colourant 500 g at £8.48 (4.4 from 950), gifyym at £5.16 (5.0 from one review) and a generic aluminium sulphate at £5.30 (4.8 from seven). A 5.0 from one two-word review is not 1,244 comments. A bundle is both jobs. Topline sells 1 litre of named Westland liquid plus 500 g of colourant at £16.99 (4.5 from 74). Westland’s own bundle is the same sizes at £15.69, with ten reviews. Buy one only if you already need both. The fork is on hydrangea feed vs colourant.

Testsieger

Topline Topline bundle: Westland liquid feed 1 litre and colourant 500 g

9.0/10about £16.99

View offer

Plant and place before the pack

Colour is a species and soil outcome. The RHS says mophead and lacecap Hydrangea macrophylla, plus H. serrata and H. involucrata, can shift because aluminium becomes available in acid soil: blue around the acid end, mauve nearer neutral, pink on alkaline ground. White, red, and green cultivars stay as they are. H. paniculata and smooth hydrangeas such as an Annabelle do not turn blue because you added a tub. If a spoon of soil fizzes with vinegar, the RHS says that ground cannot realistically be acidified. The practical UK route is a pot of peat-free ericaceous compost and rainwater. If the butt runs dry, tap water is better than a wilted plant. Pink is limestone or chalk, not a blueing salt. The plant limits are on how to turn hydrangeas blue.

What to check on the label

None of these ten amazon.co.uk listings prints an NPK in the bullets. Mixing-ratio fields such as 1:0:0 or 7:3:6 are raw strings, not a labelled analysis. The Vitax feed’s own label states NPK 8-4-12 and says the feed does not change colour. Do not paste that ratio onto the amazon page. Westland’s colourant is about 93 percent aluminium sulphate and carries an eye-damage warning (H318) on the manufacturer page. Vitax colourant is about 15.3 percent. The two £5 powders weigh 119 g against a 100 g title and have no hazard text. Westland’s form line says Liquid, the title says 500 g, the item weight is 440 g, and reviews describe powder in a card tube.

Common questions

Do I need a hydrangea fertiliser at all?

Often, no. The RHS says regular feeding is not generally needed, and too much fertiliser makes soft leaf, fewer buds, and more frost risk. Feed a plant that is struggling on light soil, or a pot whose compost is spent. Leave a healthy border shrub that already flowers.

Is a colourant the same as a feed?

No. A feed in this set is sold as nutrients. A colourant is a salt treatment aimed at flower colour on varieties that can shift. Westland’s colourant page describes iron and aluminium salts, not a general fertiliser programme. Using one in place of the other either misses the colour or misses the nutrition.

Which plant can change colour?

Mopheads and lacecaps of Hydrangea macrophylla, plus H. serrata and H. involucrata, are the RHS group that can move with soil pH and available aluminium. White, red, and green cultivars, panicle hydrangeas, and smooth hydrangeas do not. Check the plant label before you buy a tub for blue.

What should I buy for a pot on chalk?

Buy the pot setup first: peat-free ericaceous compost and rainwater. A colourant is only the next step if the variety can shift and you still want to try for blue. Open chalk that fizzes with vinegar is not a realistic acidifying project. A feed is for tired compost, not for forcing colour through lime.

What should I buy if I want to keep pink?

Do not buy a colourant. Blueing salts push the other way. The RHS route for a shifting variety is limestone or chalk at 75–100 g per square metre in winter. A nutrient feed, if you need one at all, is a separate decision and is not a pink treatment.

Are the £5 powders the same as Westland or Vitax?

They are not the same evidence. gifyym at £5.16 has one review that says Good product. The generic aluminium sulphate at £5.30 has seven reviews. Both are titled 100 g, weigh 119 g, come from China, and print 30 ml with no hazard text. Westland and Vitax have hundreds of UK reviews and an eye warning the amazon bullets omit.

How to use hydrangea fertiliser