Content
- Coloring hydrangeas purple or pink - how does that work?
- Strong purple colored hydrangeas
- Coloring hydrangeas purposely purple
- Turn purple flowers back to pink
- Tips & Tricks
Coloring hydrangeas purple or pink - how does that work?
The color of the lush inflorescences of the hydrangea is an exciting topic, because you can influence this color with simple means. An originally pink-colored hydrangea changes the flower color to blue or purple depending on how acidic or alkaline the soil is.
Strong purple colored hydrangeas
Hydrangeas prefer acidic soils with a pH between 4 and 4.5. Many surfaces do not have the optimal values, as shown in the following table:
If you have planted the Hydrangea in a more alkaline soil, the flowers show a pink color. If the garden soil is acidic, the flowers turn blue or purple. This is due to the fact that the hydrangea from the acidic soil absorbs more aluminum, which is responsible for the coveted tint.
Coloring hydrangeas purposely purple
As a result, if a purple hydrangea changes color to pink, you must add aluminum sulphate (potassium alum, alum) to the hydrangea and acidify the soil.
You can make the soil type more acidic
work into the underground. For ecological reasons, peat should only be used in exceptional cases.
The aluminum sulfate or, alternatively, hydrangea blue can be administered together with a low-phosphorus fertilizer with a high potassium content.
Turn purple flowers back to pink
If your garden soil contains a lot of aluminum and is sour, it will discolour a pink hydrangea purple, although this is not always desirable. Again, you have the opportunity to influence the flower color specifically.
First, it is important to shift the pH of the soil to the alkaline range. Lime the soil around the hydrangea several times a year and measure the pH at regular intervals. He should ideally settle at around 6.2. In addition, you can hydrangea fertilize some time with a commercially available flower fertilizer. This contains more phosphorus than special hydrangea fertilizer and thereby inhibits the responsible for the unwanted staining aluminum uptake of hydrangea.
Tips & Tricks
You can measure the pH value of the soil with test sticks from the garden trade. These measurements should be carried out at regular intervals, as the pH value can shift back into the alkaline range due to rainwater and irrigation water.