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Hydrangea feed versus colourant: nutrients, blue, or both

Updated: October 2026

You have a nutrient bag in one hand and a blueing tub in the other, and both say hydrangea on the label. They are different jobs. A feed supplies nutrients. A colourant is an aluminium and iron salt aimed at flower colour. A bundle is only worth buying when you have already chosen both. This page makes one recommendation, and the condition sits in the same breath as the product. The [hydrangea fertiliser comparison](/hub/fertiliser-soil-and-bark-mulch/hydrangea-fertiliser) holds the ten rows. Prices are the amazon.co.uk listings captured on 19 October 2026. A qualifying purchase can earn a commission at no extra cost to you.

You have a nutrient bag in one hand and a blueing tub in the other, and both say hydrangea on the label. They are different jobs. A feed supplies nutrients.

Our top picks

Vitax Ltd Vitax hydrangea feed granules, 2 x 1 kg

Best overall

Vitax Ltd Vitax hydrangea feed granules, 2 x 1 kg
9.8/10about £11.98
View offer
Westland Westland liquid plant food 1 litre and colourant 500 g

Alternative

Westland Westland liquid plant food 1 litre and colourant 500 g
6.8/10about £15.69
View offer
Westland Westland hydrangea colourant, 500 g

Best value

Westland Westland hydrangea colourant, 500 g
9.4/10about £6.99
View offer
On this page
  1. 1.What a hydrangea feed is for
  2. 2.What a colourant is for
  3. 3.When neither
  4. 4.When both

What a hydrangea feed is for

A feed is for a spent pot or a shrub on light soil that is struggling. Vitax granules, two 1 kg bags at £11.98, name magnesium and iron and do not claim a pink-to-blue change. The label, which the amazon bullets do not reprint, states NPK 8-4-12 and about 3 percent magnesium oxide, and says the feed is not designed to change colour. Do not pretend the bullet printed 8-4-12. Topline liquid, two 1 litre bottles at £16.99, says weekly use and also a spring top dressing. No NPK is printed. Shop sheets that show 4:2:6 or 4.5-2-7 are not on the amazon raw. Neudorff’s 1 kg at £12.99 says organic cultivation, with no certifier and with reviews marked Spain. Over-feeding makes soft growth, fewer buds, and frost damage. If the shrub is healthy and you are not chasing colour, buy neither. The longer refusal is the hydrangea fertiliser buying guide.

What a colourant is for

A colourant is a salt of aluminium and iron for flower colour, not a general feed. Westland’s sheet puts the mix at about 93 percent aluminium sulphate and about 7 percent ferrous sulphate, with an eye-damage warning, H318. The amazon bullets for the £6.99 tub omit that warning. Vitax colourant is about 15.3 percent aluminium sulphate. A 30 g dose of one is not a 50 g dose of the other. Rates are on how to use hydrangea fertiliser. Mopheads and lacecaps of Hydrangea macrophylla, plus H. serrata and H. involucrata, are the plants that can respond. White, panicle, and smooth hydrangeas do not. On chalk that fizzes, the realistic place is a pot. Plant limits are on how to turn hydrangeas blue. Neudorff’s pet-friendly bullet belongs to the granule feed, not to these salts.
Vitax Ltd Vitax hydrangea feed granules, 2 x 1 kg

Testsieger

Vitax Ltd Vitax hydrangea feed granules, 2 x 1 kg
9.8/10about £11.98
View offer

When neither

A white panicle needs no colourant, and it needs a feed only if it is struggling. A pink mophead you want to keep pink needs neither a colourant nor a blueing bundle. Limestone or chalk is the pink treatment. If you want growth and not a colour shift, buy Vitax granules for the labelled 8-4-12, or Topline liquid if you accept no printed NPK. If you want a pink-to-blue shift on a mophead or lacecap, buy a colourant and do not expect the feed to do it.

When both

You need both only when the plant needs nutrients and you are attempting a colour shift on a variety that can change. Westland’s bundle is 1 litre of liquid plant food plus 500 g of colourant at £15.69, model 20600082, with only ten reviews. Topline’s bundle is 1 litre plus 500 g at £16.99, 4.5 from 74 reviews, with no NPK on the page. Vitax granules at £11.98 plus Westland colourant at £6.99 is £18.97. The same granules plus Vitax colourant at £8.48 is £20.46. The sticker saving is real. The bundle liquids still do not print an NPK, so read the pack for the dose the amazon page leaves out. High phosphorus can lock aluminium, which is a reason not to grab a general fertiliser if blue is the aim. No listing in this set is a 25:5:30 product.

Common questions

Will the feed turn my hydrangea blue?
No. The Vitax label says the feed is not designed to change colour. The amazon bullets for the granule pack talk about flowering and name magnesium and iron. They do not say pink becomes blue. If blue is the goal, the feed is the wrong packet.
Will the colourant feed the plant?
Not as a complete fertiliser. Westland describes a salt for colour, with a weekly soil drench, not a nutrient programme for a starved pot. They are not interchangeable.
When do I need both?
When the plant needs nutrients and you are also attempting a colour shift on a mophead or lacecap that can change. A healthy shrub needs neither. Separate Vitax granules plus a colourant still leave you with two labels.
Is a bundle cheaper than two separate buys?
On the 19 October 2026 shelf prices, yes. Westland’s bundle is £15.69 and Topline’s is £16.99. Vitax granules at £11.98 plus Westland colourant at £6.99 come to £18.97. The bundle liquids still have no NPK, and Westland’s number-of-items line is 1.
What if I only want greener leaves and more flowers?
Buy a feed, and only if the plant needs it. The Vitax granules are the feed whose label states an analysis and says it will not change colour. Do not buy a colourant for leaf colour. Do not start a weekly liquid on a shrub that already flowers well.
What if the plant is white or a panicle?
Do not buy a colourant for a colour change. Those plants do not turn blue with pH. A feed is still only for a plant that is struggling or a pot that is spent. The tub will not repaint a white head.
Which one is dangerous in the eyes?
The colourant. Westland’s sheet carries H318, serious eye damage, and the Vitax colourant label warns of eye damage and skin irritation. Amazon bullets often omit that line. Wear eye protection when you mix the salt.
Can I use the colourant to keep pink?
No. A colourant pushes a shifting variety toward blue or mauve. Pink is limestone or chalk, 75–100 g per square metre in winter, which is the opposite treatment.

Related pages

Best hydrangea fertiliser

Hydrangea fertiliser

How to turn hydrangeas blue on acid soil or in a pot

Hydrangea fertiliser buying guide: feed, colour or none

How to use hydrangea fertiliser: rates and when to stop

Sources

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.

  1. RHS, shrubby hydrangea growing guide (retrieved 19 October 2026)
  2. RHS, acidifying soil (retrieved 19 October 2026)
  3. RHS, soil pH (retrieved 19 October 2026)
  4. Agriculture Act 1970, section 68 (retrieved 19 October 2026)
  5. Fertilisers Regulations 1991 (retrieved 19 October 2026)
  6. GOV.UK, new fertiliser regulations, 19 March 2026 (retrieved 19 October 2026)
  7. Vitax Hydrangea Feed label (retrieved 19 October 2026)
  8. Westland Hydrangea Colourant (retrieved 19 October 2026)
  9. Westland Hydrangea Colourant safety data sheet (retrieved 19 October 2026)