If you have hydrangeas in your garden, you might be surprised to learn that you can easily change the colour of their big, fluffy blooms – and it’s all down to the soil they’re planted in
Hydrangeas are renowned for their stunning, voluminous flowers that bloom vibrantly in the summer, and changing their colour is surprisingly straightforward, allowing you to add variety to your garden with ease. Specific varieties, such as bigleaf hydrangeas, alter their hue based on the soil’s pH level, enabling you to naturally enhance the beauty of these plants.
To achieve blue blooms, the soil needs to be more acidic, although it’s often simpler to transform hydrangeas into a lovely pink shade instead. According to Bill Hageman, a gardening expert from Grow Organic, all you need to do is apply the correct fertiliser to produce pink blooms, as they merely require a higher soil pH.
He said: “Contrary to popular belief, hydrangeas do not need truly alkaline soil to turn pink – they just need soil that is less acidic than for blue flowers.
“If your soil has a lower, more acidic pH, you can add lime fertilisers such as oyster shell or dolomite to raise the pH to the desired level.”
Garden lime helps counteract acidic soil, increases nutrient availability, and decreases the amount of aluminium in the ground, which is what causes hydrangeas to turn blue, reports the Express.
Opt for a fertiliser rich in the nutrient phosphorus, as this also prevents hydrangeas from absorbing aluminium, resulting in pink or red flowers.
Phosphorus is the essential nutrient required for flower production, so it can aid in producing even larger and more vibrant blooms, ultimately making your garden look stunning.
Bill explained: “Adding a high phosphorus fertiliser can discourage the plants from using the aluminium that is present in the soil. This is why it is much easier to turn a pink flower blue than it is to turn a blue flower pink.”
How to turn hydrangeas pink
To achieve pink flowers, aim for a soil pH between 6.0 and 6.4, but be careful not to raise the pH too high as this could lead to a reduction in available iron.
If your soil’s pH is below 6.4, simply apply your fertiliser and ensure thorough watering to dissolve the nutrients and expedite the reaction.
Patience is key when changing hydrangea colours; it may take a full season or more. Regularly check the soil pH, continue with fertilisation and watering, and you’ll soon enjoy vibrant pink hydrangeas.
Controlling soil pH is generally more straightforward in pots compared to garden beds, so for those planting new hydrangeas, pot cultivation might yield quicker colour changes.