Coloring hydrangea blue - how do you do it?

Coloring hydrangea blue - how do you do it?

Acid soil as a basic requirement

So that the hydrangea can absorb the trace elements responsible for the blue color from the soil, the soil must have a pH value below 4.5. However, only a few garden soils are this acidic.

also read

  • Coloring hydrangeas purple or pink - how does it work?
  • Hydrangeas: flowers in many different colors
  • The hydrangea: the blooming chameleon of the garden

remedy

  • Replace the topsoil with special hydrangea or rhododendron soil when you plant the hydrangea.
  • Analyze the pH value regularly with test strips from a gardening specialist.
  • If this value is too high, it can be reduced by adding composted leaves or ripe compost.
  • Pouring vinegar water also lowers the pH.

Irrigation water

Liming shifts the pH value of the soil towards alkaline and the hydrangea loses its beautiful blue color. Therefore, water the plant in regions with calcareous water only with soft rainwater.

Coloring a hydrangea blue

For a pink hydrangea to turn blue, acidification of the soil is usually not enough. In addition, you have to add the aluminum responsible for the blue coloration to the earth.

You can add either commercially available hydrangea blue or, alternatively, potash alum to the irrigation water. Out of consideration for the environment, please follow the instructions on the packaging.

Discoloration occurs slowly

It can take up to two years for the hydrangea to turn completely blue. First of all, attractive shades such as violet or a bluish pink appear. Usually even the flowers of an umbel are shaded differently, which gives the plant a special charm.

Tips & Tricks

The rumor circulates again and again that coffee grounds and grated eggshells used as fertilizer color the hydrangea blue. In fact, eggshells add calcium to the soil. Coffee pomace improves the soil structure and shifts the pH value somewhat into the acidic range. On their own, however, these measures are only sufficient if the garden soil is relatively acidic anyway.