Does Hydrangea Colourant Really Work?
Hydrangea colourant will change pink hydrangea flowers to blue but will not change blue flowers pink. The colour of a hydrangea flower will be blue if the plant is growing in acid soil and pink if the plant is growing in alkaline soil. You cannot change the colour of white hydrangea flowers. Changing the colour of hydrangeas is dependent on a couple of conditions:
- Whether the Hydrangea plant was bred to be a specific colour.
- The acidity of the soil the hydrangea plant is growing in.
How does Hydrangea Colourant Work?
Hydrangea colourant works by changing the PH of the soil from alkaline to acid, i.e. changing the colour of the hydrangea flowers from pink to blue. There is no hydrangea colourant available for changing the colour of the flowers from blue to pink. However, it is possible to change blue hydrangea flowers to pink by adding garden lime slowly over time.
- Pale pink varieties tend to blue best
- Darker pink varieties turn to mauve/blue
Planting a hydrangea in a pot is the best way to get the colour of the hydrangea flowers you want. When potting up the shrub, simply use ericaceous compost for blue flowers and use ordinary potting compost for pink flowers.
If your hydrangea is growing in a border and you would like to change the colour of the flower. Use a soil testing kit to give you an idea of the soils PH level. You will already know that blue flowers occur in acidic soil. There may be too much of a change in PH required to increase the alkalinity of the soil to get pink flowers by adding garden lime.