Let's Dance ® Blue Jangles TM Reblooming Hydrangea - 4" Pot - Proven Winners
The Let's Dance reblooming series continues to improve and expand with Blue JanglesTM, a compact selection with delightful rich blue (or pink) mophead flowers. A real standout in the garden and in the container because of its sturdy frame and its propensity to bloom.For Blue Flowers: Aluminum availability determines flower color. The availability of aluminum makes the flowers turn blue. Without aluminum the blooms will be pink. Soil pH must be low or acid (5.2-5.5) for the plant to absorb the aluminum. Color changes need time to take effect. Drench with aluminum sulfate immediately after planting. A solution of  oz (1 Tbsp) per gallon is a good start. Be sure the plants are well-watered before applying the aluminum sulfate as it can burn the roots. (important!!!) Drench again in 10-14 days. Alternatively, you may apply a controlled-release form of aluminum sulfate. Products such as Blue-Knight will release aluminum sulfate over a three month period. This is safer. Some varieties shift to blue more easily than others.Consistent treatment is necessary to turn your hydrangeas blue. Plant your hydrangeas in a phosphorous-free medium, and use a phosphorus-free fertilizer with lots of potassium (i.e. 25-5-30).