Why Are My Pink Hydrangeas Changing Colour?
If you've noticed your once-vibrant pink hydrangeas shifting to blue or purple, don't panic – it's not magic, but science! The colour of hydrangea blooms is directly influenced by the pH level of your soil. Acidic soil (with a pH below 6) tends to produce blue flowers, while alkaline soil (pH above 7) results in pink blooms. Neutral pH? You might get a stunning purple mix!
The Science Behind the Colour Shift
The key player in this colour transformation is aluminium. In acidic soil, aluminium becomes more available to the plant, which then alters the flower's pigment. For gardeners who prefer pink hydrangeas, maintaining a soil pH between 6.0 and 6.2 is crucial.
How to Keep Your Hydrangeas Pink
- Test your soil – Use a pH testing kit to determine your soil's current level
- Add lime – For soils that are too acidic, applying garden lime can help raise the pH
- Choose the right fertiliser – Opt for a high-phosphorus fertiliser (like 25-10-10) to discourage aluminium uptake
- Consider container gardening – If your native soil is very acidic, growing hydrangeas in pots with controlled soil might be easier
When to Expect Changes
Don't expect overnight results! Soil amendments can take several months to fully affect your hydrangeas' colour. The changes you make now will be most visible in next season's blooms.
Expert Tip for Instant Impact
For gardeners who want quicker results, consider using a liquid soil drench specifically formulated for hydrangea colour control. These products can produce noticeable changes within weeks rather than months.
