soil ph dictating on Hydrangea
Quick answer
If your Hydrangea has soil ph dictating, the most likely cause is: Flower color on macrophylla and serrata hydrangeas shifts due to soil pH dictating aluminum availability. Acidic soil (pH < 6.0) makes aluminum accessible, causing blue blooms. Alkaline soil (pH > 6.0) restricts aluminum, causing pink blooms. Hard water can also increase pH over time, turning blue hydrangeas pink.
Start here:
- 1. To turn pink flowers blue, lower pH by adding soil acidifier (elemental sulfur or aluminum sulfate) starting in late winter.
- 2. To turn blue flowers pink, raise pH by applying garden lime (calcium carbonate) to the soil.
Why Hydrangea gets soil ph dictating
Flower color on macrophylla and serrata hydrangeas shifts due to soil pH dictating aluminum availability. Acidic soil (pH < 6.0) makes aluminum accessible, causing blue blooms. Alkaline soil (pH > 6.0) restricts aluminum, causing pink blooms. Hard water can also increase pH over time, turning blue hydrangeas pink.
How to reverse soil ph dictating on Hydrangea
- 1
To turn pink flowers blue, lower pH by adding soil acidifier (elemental sulfur or aluminum sulfate) starting in late winter.
- 2
To turn blue flowers pink, raise pH by applying garden lime (calcium carbonate) to the soil.
- 3
Check the baseline soil pH before amending to avoid toxic buildup of salts or excessive acidity.
Keep soil ph dictating off this Hydrangea
Amend the soil consistently every season and avoid watering blue hydrangeas with hard tap water or water runoff from new concrete (which leaches lime).