Growing a purple hydrangea is easy if you have the right growing conditions. The color depends on the amount of aluminum in the soil as well as acid level, which can result in white, blue, purple, and pink. It's possible to customize the color by adjusting those factors. To grow lush purple hydrangeas, follow these gardening techniques.
Plant your hydrangea in partial sun conditions. Direct sun during midday is too harsh for most varieties and will damage them.
Ensure that the soil has aluminum present and maintains a pH of 5.5 to 6.5. If the acid level changes, traces of aluminum diminish and you'll get different colored blossoms. For example, pH level 5.5 and lower results in blue flowers, while pH level 6.5 and higher results in pink flowers.
Test aluminum level in your soil by giving a soil sample to a local testing office. Many cities have a Cooperative Extension office that provides this service.
To put aluminum into your soil, add 1 tablespoon of aluminum sulfate per gallon of water to the plants. Make the soil more acidic by using coffee grounds, citrus peels, and grass cuttings.
Ensure the soil is rich and drains well. Avoid clay-based soils.
Water plants well after first planting. Apply water to them every 3 days for about 3 weeks. Then one established, apply only enough water to keep the flowers from drooping. Avoid overwatering as hydrangea thrive with moist soil but not wet soil. In hot climates, more watering may be needed.
Apply a fertilizer that is low in phosphorous and high in potassium up to 2 times during the summer. Avoid fertilizing after August since the plant goes into a dormant phase. If you stimulate new growth, the plant may be damaged during colder temperatures. For chemical free nutrients, apply manure around the soil.