The best hydrangea fertilisers, compared.
Top pick: gifyym hydrangea blueing acidifier, 100 g Best value: Westland hydrangea colourant, 500 g – Lowest shelf price among the remaining listings with 100 or more reviews, and a colourant rather than a feed, at about £6.99. Updated October 2026.
A hydrangea fertiliser is a nutrient feed or a colour treatment for mophead and lacecap shrubs in a UK border or pot. A feed supports leaves and flowers. A colourant supplies aluminium so some pink flowers can shift toward blue, and only in acid soil where that aluminium stays available. A healthy shrub on decent soil often needs mulch and water before a weekly liquid. You tell a suitable pack by the job, the plant, and the soil. Colour can shift on some Hydrangea macrophylla mopheads and lacecaps, and on H. serrata and H. involucrata. White cultivars stay white. Panicle and smooth hydrangeas do not shift with pH. Open chalk is a poor place to force blue. A pot of ericaceous compost and rainwater is the practical route. On a feed, look for a printed nutrient ratio. On a colourant, look for a named aluminium salt and an eye-damage warning. Which type to buy, including when not to buy, is set out in the [hydrangea fertiliser buying guide](/hub/fertiliser-soil-and-bark-mulch/hydrangea-fertiliser/sub/hydrangea-fertiliser-buying-guide).
A hydrangea fertiliser is a nutrient feed or a colour treatment for mophead and lacecap shrubs in a UK border or pot. A feed supports leaves and flowers.
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Personal buying guide
Question 1 of 2
What do you want the pack to do?
gifyym lists a hydrangea blueing acidifier at £5.16, titled 100 g of aluminium sulphate, with China as the country of origin and an item weight of 119 g. The bullets say it must be diluted, then you sprinkle 30 ml and water, which matches the mixing-ratio field. The title says it turns hydrangeas blue and includes the words “for safe use”, but the pet-safety question has no answer and there is no hazard text in the raw. The star line is 5.0 from one review, and that body is the two words “Good product”, so there is no result and no criticism to weigh. Bullets also mention containers, clay and sandy soils, ornamental shrubs, and garden ponds, while questions on other plants and all soil types go unanswered. A perfect star from a single two-word review is why the score is cut back from 100. No NPK is printed.
Pros
Cons
Best for: You want the cheapest titled aluminium-sulphate pack in this set and you do not need review evidence.
Less suitable: You want UK review comments, a hazard line, or a named garden brand.
Specifications
Common questions
What is named on the title?
The title is a hydrangea blueing acidifier, aluminium sulfate, 100 g, brand gifyym, origin China. The item weight is 119 g. No percentage and no NPK are printed.
Does the listing answer the pet question?
The question 'Is it safe for pets?' is on the page with no answer. The title includes 'for safe use'. No hazard text is in the raw. The dose line is 30 ml per application, diluted, sprinkled, then watered.
What is the review sample?
The star line is 5.0 out of 5 from 1 review. The only body says 'Good product', so there is no criticism to aggregate.
This Vitax listing is a powder at £39.29, and the unit count is 1000 gram while the title reads 1KG (6) and the coverage field is 6. The saved listing does not confirm six kilograms, so the title suffix is not a reason to assume a six-pack. There are no product bullets, no dose, and no manufacturer line. No NPK is printed, and the mixing-ratio field reads 1:0:0. The star line is 5.0 from one review, and no review body is in the file. Best Sellers Rank is 280,920 in Garden, far below the 2 kg granule listing from the same brand name. At this price, with the pack size unresolved, the scaled star line is not evidence you can shop by.
Pros
Cons
Best for: You have already confirmed with the seller that this ASIN is the pack size you want.
Less suitable: Anyone choosing from the listing alone, or anyone comparing it with the 2 x 1 kg granule at £11.98.
Specifications
Common questions
How much is in the pack?
The unit count is 1000 gram. The title is Vitax Hydrangea Feed 1KG (6), and the coverage field is 6. The saved listing does not confirm six kilograms. The item form is powder.
Is an NPK or a dose printed?
No. There are no product bullets. The mixing-ratio field reads 1:0:0. Manufacturer, part number, and item weight are absent.
What is the star line?
5.0 out of 5 from 1 review. No review body is in the raw, so there is nothing to aggregate.
This generic listing is titled as 100 g of aluminium sulphate to turn hydrangeas blue, at £5.30, with China as the country of origin and an item weight of 119 g. The mixing-ratio field says 30 ml per application, and a bullet says sprinkle thirty millilitres, then water, after diluting. The star line is 4.8 from 7 reviews, and only one UK body is in the file. That reviewer reports no clear colour change yet and mentions drought and a hosepipe ban, so they do not treat it as a fair trial. There is no hazard text in the raw, no NPK, and the item form says refer to the description. Questions on other plants and how often have no answer. The low price is for a small title weight with a thin review file, so it does not outrank the colourant tubs that have hundreds of UK comments.
Pros
Cons
Best for: You already intend to use a small aluminium-sulphate dose and you accept a seven-review file.
Less suitable: You want a named UK brand, a hazard line, or more than one written review.
Specifications
Common questions
What does the title say this is?
The title calls it an aluminium sulphate soil acidifier, 100 g, to turn hydrangeas blue. The brand line is Generic and the country of origin is China. The item weight is 119 g. No NPK and no hazard text are in the raw.
What dose is printed?
The mixing-ratio field says 30 ml per application. A bullet says sprinkle thirty millilitres on the soil and water afterward, and that it should be diluted before use. A question on how often has no answer.
How many review bodies are in the raw?
The star line is 4.8 out of 5 from 7 reviews. One UK body is present. It reports no clear colour change yet and mentions drought and a hosepipe ban.
The Topline pack is two 1 litre bottles of liquid hydrangea feed at £16.99, and the bullets tell you to feed weekly in a container or in the ground as well as at planting and as a spring top dressing. Across 68 amazon.co.uk reviews the line is 4.7, and the 17 UK bodies often describe more or larger flowers, including after a different feed gave fewer blooms. Several of those reviews are only a word or two, so they do not show how the liquid was mixed. One reviewer says it is too soon to judge, and another could not rate the bottle because squirrels had damaged a young plant. No NPK is printed in the bullets, and the mixing-ratio field reads 1:0:0, which is not a labelled analysis. Country of origin is the United Kingdom and the item weight is 3 kg for the 2 litre pack. No leak, smell, or plant-death report repeats in those 17 bodies, though you still have no numeric dose.
Pros
Cons
Best for: You want a UK liquid feed for pots or a border and you are not trying to turn pink flowers blue.
Less suitable: You need a printed NPK, a millilitre rate, or a colourant.
Specifications
Common questions
Is this a colourant or a liquid feed?
The item form is liquid, and the title is a pack of 2 x 1 litre hydrangea flower feed. The bullets do not say it changes flower colour. The mixing-ratio field reads 1:0:0, and no NPK is printed.
How does the listing say to apply it?
One bullet says feed weekly, in containers or in the ground. Another says apply at planting and as a spring top dressing, then water in dry weather. No numeric dose is printed.
What do the UK reviews in the saved listing say?
The star line is 4.7 out of 5 from 68 reviews. In the 17 review bodies, people often mention more or larger flowers and ease of use. A few say it is too soon to judge.
This Topline bundle pairs 1 litre of Westland liquid hydrangea feed with 500 g of colourant at £16.99, while the brand line still says Topline. The colourant bullet calls it a salt that changes pink varieties to blue and darker pink varieties to mauve blue, with best results in acid soil, or ericaceous compost on alkaline soil, or a doubled rate. The feed bullets say weekly use and also a planting or spring top dressing, and neither part prints an NPK or a gram dose. Across 74 reviews the line is 4.5, and the 10 UK bodies mostly say it helped or matched the description. One report describes powder flowing from a damaged pack. Another reviewer is unsure whether a single use of each product left leaves and flowers brown and crispy. The item form line says granules and liquid, the liquid volume is 1 litre, and the mixing-ratio field reads 1:0 or 0:1.
Pros
Cons
Best for: You want the feed and the colourant in one order and you already have acid soil or you will use ericaceous compost.
Less suitable: You only need a nutrient feed, or you want a large review file about the colour change itself.
Specifications
Common questions
What is in the bundle?
The title is 1 litre Westland hydrangea liquid plant food and 500 g hydrangea colourant, with a Topline card. Brand and manufacturer lines say Topline. The item form line says granules and liquid.
Does the listing claim a colour change?
The colourant bullet says it is a salt that changes pink hydrangea varieties to blue and darker pink varieties to mauve blue. It says to use acid soil, or ericaceous compost on alkaline soil, or to double the rate. No NPK is printed.
What do the reviews in the saved listing say?
The star line is 4.5 out of 5 from 74 reviews. In 10 UK bodies, some say it helped or matched the description. One reports powder leaking from a damaged pack, and one is unsure whether one use left leaves and flowers brown and crispy.
Vitax lists two 1 kg bags of granules at £11.98, model 6HF1, and the bullets name added magnesium and iron without percentages or an NPK. You are told to work it into the soil at planting and to top-dress in spring, with no grams-per-square-metre figure on the amazon.co.uk page. Across 1,741 reviews the line is 4.4, the largest sample in this set, and the first 50 UK bodies often mention more blooms, larger heads, and new shoots on plants that had looked finished. Two of those reviews mention feeding every six to eight weeks, which is the reviewers’ habit rather than a rate on the listing. One buyer says the bags are not 1 kg, another reports granules leaking from torn packs, and one says overfeeding killed young plants and that this was their own fault. A different review did not want a pink hydrangea to turn blue. The safety bullet says keep the bags away from children and animals and wear gloves. The score of 88 is the star line scaled to 100, and this is the top pick because no larger UK sample sits above it.
Pros
Cons
Best for: You want a granular hydrangea feed for planting or a spring top dressing and you care more about a large UK review file than a colour change.
Less suitable: You are chasing blue flowers, you need a printed NPK on the amazon page, or you are feeding very young plants and tend to over-apply.
Specifications
Common questions
Does this listing print an NPK?
No NPK ratio is printed in the bullets. The mixing-ratio field reads 1:0:0. A bullet says the feed contains added magnesium and iron, with no percentages. The item form is granules, 2 x 1 kg in the title.
How does the listing say to apply it?
Incorporate it into the soil at planting and reapply as a top dressing in spring. No gram rate is printed. The safety bullet says store it cool and dry, keep it away from children and animals, and wear gloves.
Is it described as a colourant?
The bullets talk about flowering and vibrant colour. They do not say the feed turns pink flowers blue. The pet-friendly question has no answer.
Vitax sells a 500 g colourant, model 566646, at £8.48, and the bullets say pale pink varieties tend to blue best while darker pink varieties turn mauve or blue. There is no item-form line and no gram rate; the instruction bullet says treat as per the pack. Across 950 reviews the line is 4.4, and the first 50 UK bodies often describe a shift to blue or purple in pots when people start in May or continue through flowering, which is their timing rather than a printed schedule. Several reviews report no change, and one says a large plant stayed purple because it needed more powder. One tub was reported contaminated with peppercorns, leaf fragments, and twigs, and the reviewer says Vitax asked for a return. Part of the white powder is described as hard to dissolve, and one review questions a ferrous sulphate claim because the powder is not green, which is a review statement rather than a listing analysis. Ground results are more mixed than pot results in one review. At £8.48 it costs £1.49 more than the Westland 500 g title, with a higher star line and fewer notes about crushed tubes.
Pros
Cons
Best for: You want a 500 g Vitax colourant with a large UK review file and you are starting on a pale pink plant in a pot.
Less suitable: You need a nutrient feed, a printed dose on the amazon page, or a white variety the listing does not cover.
Specifications
Common questions
What pack is this?
The title and unit count are 500 g of Vitax hydrangea colourant, model 566646. There is no item-form line. Material features say Colourant. The colour field on the listing reads Pink. No NPK is printed.
What colour claim is on the listing?
Pale pink varieties tend to blue best, and darker pink varieties turn to mauve or blue. The instruction bullet says treat as per the pack. No gram rate is in the raw. A question about all varieties has no answer.
What do the first 50 UK reviews mention?
The star line is 4.4 out of 5 from 950 reviews. Many describe a pink-to-blue or purple shift when they start earlier in the season. Others report no change, a lot of powder on a large plant, or, in one case, contamination in the tub.
Westland’s bundle is 1 litre of liquid plant food plus 500 g of colourant at £15.69, and the colourant model on the bullet is 20600082, the same number as the standalone colourant. Feed bullets claim stronger plants, bigger blooms, nitrogen for greener leaves, and a moisture-control booster, with no ratio and no dose. Colourant bullets repeat pale pink to blue and dark pink to mauve blue. The item form line says Liquid, the liquid volume is 1 litre, the item weight is 500 g, and the number of items line is 1 even though the title names two products. Across 10 reviews the line is 4.4, and only three UK bodies are in the file. Two mention a large mop of flowers or bigger plants, and one says the plants stayed the same when used as directed. That sample is too small to treat 4.4 as a ranking, and there is still no NPK.
Pros
Cons
Best for: You want Westland’s liquid and the 20600082 colourant in one order and you will judge the pack by the label, not by ten reviews.
Less suitable: You want a large UK sample, or you only need one of the two products.
Specifications
Common questions
What does the title include?
The title is Westland liquid plant food, 1 litre, and hydrangea colourant, 500 g. The item form line says Liquid. Liquid volume is 1 litre and item weight is 500 g. The number of items line is 1. Model number 20600082 is the colourant model on the bullet.
What does each part claim?
Product 1 bullets say stronger plants, bigger blooms, nitrogen for greener leaves, and a moisture-control booster. Product 2 bullets say pale pink hydrangeas change to blue and dark pink to mauve blue. No NPK and no dose are printed.
What is in the three UK reviews?
The star line is 4.4 out of 5 from 10 reviews. Two bodies mention a large mop of flowers or bigger plants. One says it was used as directed and the plants stayed the same.
Westland’s colourant is titled 500 g at £6.99, model 20600082, and the first 50 of 1,244 UK reviews often describe a pink shift toward blue or purple when people start in spring and water the base. The star line is 4.2. The item form line says Liquid and the item weight is 440 g, while those review bodies describe powder or granules in a card tube, so the listing and the pack do not agree. No dose is printed in the bullets, yet one reviewer says the amount stated on the pack nearly killed a plant. Crushed tubes, leaking powder, and a flimsy lid that does not seal come up repeatedly in that sample. The bullets promise pale pink to blue and dark pink to mauve blue, and a question about white hydrangeas has no answer. Country of origin is the United Kingdom. At £6.99 it is the lowest shelf price among the listings here with more than 1,000 reviews, which is why it is the best value, not because the tube is sturdy.
Pros
Cons
Best for: You already have a pale pink mophead or lacecap and you want the cheapest widely reviewed colourant in this set.
Less suitable: You need a nutrient feed, a white hydrangea to turn blue, or a tub that reviewers describe as well sealed.
Specifications
Common questions
Is the listing a liquid or a 500 g pack?
The title is Westland Hydrangea Colourant, 500 g, and the item weight is 440 g. The item form line says Liquid. Review bodies describe powder or granules in a card tube. No NPK is printed.
What colour change does the listing claim?
The bullets say pale pink hydrangeas change to blue and dark pink hydrangeas to mauve blue. A question about white hydrangeas is on the page with no answer. No dose is printed in the bullets.
What comes up in the first 50 UK reviews?
The star line is 4.2 out of 5 from 1,244 reviews. Many describe a shift from pink toward blue when they start early and water the base. Repeated complaints are crushed tubes, leaking powder, a flimsy lid, and one report that the stated dose nearly killed a plant.
Neudorff Azet is a 1 kg granular fertiliser at £12.99, model 81578, and the bullets say it can be used in organic cultivation, has an immediate and long-term effect, and is pet-friendly. No certifier is named, and there is no colour-change claim. Specific uses listed are hydrangeas, azaleas, heathers, and camellias. No NPK is printed in the bullets; the mixing-ratio field reads 7:3:6, which stays a field string rather than a labelled analysis. The star line is 4.0 from 4 reviews, and both bodies in the raw are marked as reviewed in Spain. One calls it a good product. The longer one says a small handful helps acid-loving plants in flower and that they usually prefer humus or vinegar water. There is no gram rate and no UK review body, and the item-form line in the raw reads Granulados.
Pros
Cons
Best for: You want a 1 kg granule with an organic-cultivation bullet and a pet-friendly line, and you accept a four-review file from Spain.
Less suitable: You need UK review comments, a printed dose, or a named organic certifier.
Specifications
Common questions
What claims are on the bullets?
The bullets say it can be used in organic cultivation, has an immediate and long-term effect, and is pet-friendly. No certifier is named. The item form line reads Granulados, and the title is 1 kg.
Is an NPK printed?
No NPK line is in the bullets. The mixing-ratio field reads 7:3:6. Specific uses listed are hydrangeas, azaleas, heathers, and camellias. There is no colour-change claim.
Where were the review bodies written?
The star line is 4.0 out of 5 from 4 reviews. The two bodies in the raw are marked as reviewed in Spain. One calls it a good product. The other says a small handful helps acid-loving plants in flower and that they usually prefer humus or vinegar water.
Ten amazon.co.uk listings were scored from the stored pages and the UK review notes already on file. Shelf date 21 October 2026. There is no laboratory test. A listing with 100 or more reviews scores the star rating multiplied by 20, so 4.4 becomes 88 and 4.2 becomes 84. Files of 20 to 99 reviews lose 10 points, files of 2 to 19 lose 30, and a single review or a star line with no review body loses 50. No listing prints an NPK in the bullets. Mixing-ratio fields are copied as raw strings and are not an analysis. The highest score, and on a tie the larger review count, is the top pick. The best value is the lowest shelf price among the remaining listings with 100 or more reviews, and a different job from the top pick. The weights below sum to 100.
Amazon star line
70%The amazon.co.uk star rating multiplied by 20. A line of 4.4 becomes 88. A line of 4.2 becomes 84. That scale is not a trial of flower size or of a pink-to-blue shift.
Review sample
30%100 or more reviews: no deduction. 20 to 99 reviews: 10 points off. 2 to 19 reviews: 30 points off. One review, or a star line with no review body: 50 points off, so a thin file cannot outrank a large UK sample.
Buy the job before you buy the star line. A feed, a colourant, and a bundle are not one list. Prices below are amazon.co.uk shelf prices on 19 October 2026. This is not a laboratory test.
A hydrangea fertiliser on amazon.co.uk is either a nutrient feed, in granules or as a liquid, or a colourant that supplies aluminium so some mopheads and lacecaps can turn blue. UK buyers are sorting those two jobs. The Royal Horticultural Society says regular feeding in the ground is often unnecessary, and that too much fertiliser makes soft leaf, fewer flowers, and more frost damage. Colour shifts only on some types, mainly Hydrangea macrophylla mopheads and lacecaps plus H. serrata and H.
A nutrient feed and an aluminium colourant do different jobs. Bullets that say vibrant colour are not a promise of a pink-to-blue shift.
White cultivars, Hydrangea paniculata, and H. arborescens do not turn blue. Open chalk is a poor place to force the shift. One July watering is too soon to judge.
The Royal Horticultural Society says regular feeding in the ground is often unnecessary. Too much fertiliser makes soft leaf, fewer flowers, and more frost damage. Do not double the dose on chalk.
Match the job before the star line. A feed is for leaves and flowers. A colourant is for a pink-to-blue shift on plants that can change, and only where aluminium stays available. A bundle is both in one order. A healthy border shrub is often a case for mulch and water, not a weekly liquid. The Royal Horticultural Society says regular feeding in the ground is often unnecessary, and that too much fertiliser makes soft leaf, fewer flowers, and more frost damage. The plant comes next.
Read the label for the job you are buying. On a feed, a printed NPK is the clear line. The Vitax Hydrangea Feed label is NPK 8-4-12 plus 3 percent magnesium oxide, and the feed does not change colour. The amazon.co.uk bullets on the 2 × 1 kg listing do not print that ratio, and no listing in this set prints an NPK in the bullets. A mixing-ratio field such as 1:0:0 or 7:3:6 is a raw string, not a labelled analysis. On a colourant, look for a named aluminium salt and an eye-damage warning.
Three typical situations, each with a recommendation from this comparison.
Mulch and water before you buy a weekly liquid. If you still want a planting feed or a spring top dressing, Vitax hydrangea feed granules, 2 x 1 kg, are about £11.98, with 4.4 from 1,741 reviews. The bullets name magnesium and iron and do not claim a pink-to-blue shift. There is no gram rate on the listing.
You need ericaceous compost, rainwater, and a colourant, and only on a mophead or lacecap that can shift. Vitax hydrangea colourant, 500 g, is about £8.48, with 4.4 from 950 reviews. The bullets say pale pink varieties tend to blue best. There is no gram rate; the listing says treat as per the pack.
Westland hydrangea colourant, 500 g, is about £6.99, with 4.2 from 1,244 reviews. It is the lowest shelf price among the listings here with 100 or more reviews. The title says 500 g, the item weight is 440 g, and the item form line says Liquid. Treat a one-review powder as unscored.
The top pick is Vitax hydrangea feed granules, 2 × 1 kg, at about £11.98. amazon.co.uk shows 4.4 from 1,741 reviews, the largest sample in this set, and the bullets name magnesium and iron without a pink-to-blue claim. The best value is Westland hydrangea colourant at about £6.99, with 4.2 from 1,244 reviews. It is the lowest shelf price among the remaining listings with 100 or more reviews, and it is a colourant rather than a feed. The item form line says Liquid, the title says 500 g, and the item weight is 440 g. Neither result is a laboratory test, and neither is a reason to feed a healthy shrub every week.
Westland hydrangea colourant, 500 g
Lowest shelf price among the remaining listings with 100 or more reviews, and a colourant rather than a feed, at about £6.99.
Editorial
Peter F. is the editor for DIY & tools at productscompared.co.uk. Comparisons in this category are checked against amazon.co.uk listings, review evidence and public UK sources.
Guides on what to look for, how to use a product, and common mistakes.
Public UK and maker sources from the research digest, used for this page in October 2026. Prices, stars and review counts are from the ten amazon.co.uk listings captured on 19 October 2026. Scores follow the 21 October 2026 shelf note. The NPK 8-4-12 line is the Vitax label, and it is not printed in the amazon bullets. Aluminium percentages and the eye-damage class are from the maker sheets named below, not from an amazon bullet. The March 2026 GOV.UK item was a consultation, not a shopping rule.
Expert source (DIY & tools): Lee Burkhill (Garden Ninja) (external profile) – public expert commentary used as a research source, not as a contributor to our pages.
This page contains affiliate links to amazon.co.uk (tag pcuk26-21). If you buy through them, we may earn a commission at no extra cost to you. Prices, stars and review counts are from the listings. This is not a laboratory test.
