What water should I use for colored hydrangeas?
Written by
Nguyen Minh
Reviewed by
Prof. Martin Thorne, Ph.D.The colour of your hydrangeas depends on the water you use. Rainwater keeps the soil acidic, and you will get blue flowers. If you use tap water, you will gradually increase the pH of the soil and get roses; if you have hard water full of alkali, you will defeat your purpose. I did, for my blue hydrangeas were mauve after watering a new shrub from my well. Soft water is the best, for it controls the extractive values of the soil, especially in aluminium.
Rainwater
- Naturally acidic pH 5.0-5.5 maintains blue colors
- Contains no minerals that alter soil chemistry
- Collect using barrels during storms for consistent supply
Tap Water
- Alkaline pH 7.0-8.5 promotes pink blooms
- Calcium carbonate gradually elevates soil pH
- Use municipal water for pink hydrangea beds
Hard Water
- High mineral content neutralizes soil acidity
- Causes white crust on soil surface over time
- Avoid completely for blue hydrangea care
Water smart. Wet the soil! Not the leaves. Water in the early morning to prevent evaporation. Use soaker hoses that penetrate deeply. I water my blue hydrangeas with rainwater twice a week. My pink ones get the tap water every three days. They are the perfect shade of pink.
Proper watering habits prevent foliage problems. Watering at the base of the plant itself, rather than over the leaves, also prevents fungal disease on the foliage. As with everything, adjust your amounts from season to season; provide plenty for your plants in the summer months and little in the winter. My hydrangeas had root rot; the culprit was overhead sprinklers. Drip irrigation solved that problem!
Hard water is a nightmare to deal with. It leaves its minerals behind. It toils aluminum into the ground, and crusting means there's too much calcium. If your water is hard, you'll want to get some rain barrels. I went to work with a pine needle mulch that I confess I thought of as merely cheap. Still, it is naturally acidic and helps diminish the effects of hard waters slowly.
Read the full article: Soil pH for Hydrangeas: Color Control Guide
