westland garden health logo
Rollover to zoom
Hydrangea Colourant is a salt which changes the colour of pale pink hydrangea varieties to blue and darker pink varieties to mauve blue.
  • A combination of iron & aluminium salts
  • Acidifies the soil to produce blue flowers

Sizes available

  • 500g
  • Product Details
  • how to use
  • tips & advice
  • Useful Information

Why Use

To help rooting and establishment of cuttings

What to Expect

Pink Hydrangeas will produce blue flowers and darker pink Hydrangeas will be mauve. Some Hydrangeas are bred to show pink flowers in all conditions — please check the plant label.

When to Use

April to September


How to Use

Established shrubs

Mix the Hydrangea Colourant into the soil at the rate of 50g per square metre.

Every 7 days during the growing season dissolve 50g of hydrangea colourant in 5 litres of water and apply to the area of soil covered by the shrub.

Do not apply directly on plant foliage.

Container-grown Hydrangeas

When potting, mix the Hydrangea Colourant into the compost at the rate of 50g per 5 litres of compost.

Every 7 days during the growing season dissolve 50g of hydrangea colourant in 5 litres of water and water the soil round the plant.


Best results are obtained with plants growing in acid soils. Where the soil is naturally alkaline use an Ericaceous compost (such as John Innes Ericaceous Compost or Gro-Sure Ericaceous Compost) instead or double the application rate

Frequently Asked Questions

Q. Will my pets or wildlife be attracted to this product?

A. Hydrangea Colourant doesn’t contain any organic elements so shouldn’t be attractive to animals.

For any other questions or advice please contact our Technical Advice line on:  01480 443789 (Mon-Fri 9am- 5pm) or email customerservice@westlandhorticulture.com

Safety Information

WARNING: Causes Serious Eye Damage

Contains Aluminium Sulfate Hexadecahydrate CAS No. 10043-01-3

  • Wear protective gloves/protective clothing/eye protection/face protection
  • Keep out of reach of children

If in Eyes:

  • Rinse cautiously with water for several minutes
  • Remove contact lenses, if present and easy to do. Continue rinsing
  • Immediately call a Poison Centre or doctor/physician

You Might Also Like

Recently Viewed Products