Spotlight on: Hydrangeas

The Lace-cap hydrangea is one of the most widely recognized species of hydrangeas. They are called Lace-caps for their lacy horizontal blossoms and large globes of rich colored flowers. These flowers grow in moist, well-drained soil with sun or at least partial shade. The only shelter needed is from the drying winds. These flowers grow in clumps up to 6 ft in height. 

These flowers can be maintained by cutting back to the first pair of buds beneath the old flower during the spring. They bloom during the fall and summer seasons and are frost tolerant. 

The unique thing about hydrangeas are that you can control what color the flower will be based on the type of soil. To change the color of your hydrangeas, follow these directions.

To change to Pink 

For the flowers to be pink the plant must not take up any aluminum from the soil. if the soil naturally contains aluminum, you must try to keep it away from the hydrangea's system. Here's a few tips and tricks:

•  Add dolomitic lime several times a year. This will help to raise the pH. Shoot for a pH of about 6.0 to 6.2. Since hydrangeas take up aluminum best at lower pH levels, raising the pH will help to keep the bluing effect of aluminum out of the hydrangea's system.
• Use a fertilizer with high levels of phosphorus. Phosphorus helps to prevent aluminum from entering into the system of the hydrangea. 
• In areas that naturally produce blue hydrangeas (soils with aluminum), consider growing pink hydrangeas in large pots. If hydrangeas are grown in pots, it would be best to use soil-less mixtures, since these mixes would probably not have aluminum in them. In a pot, it will be much easier to control the requirements for growing pink hydrangeas.

To change to Blue

To obtain a blue hydrangea, aluminum must be present in the soil. To ensure that aluminum is present, aluminum sulfate may be added to the soil around the hydrangeas.

• We recommend a solution of 1 Tbsp aluminum sulfate per gallon of water be applied to plants (which are at least 2-3 years old) throughout the growing season. Important: Water plants well in advance of application and put solution on cautiously, as too much can burn the roots. 
• Add organic matter to the soil such as coffee grounds, fruit and vegetable peels, grass clippings etc.
• If the soil naturally contains aluminum and is acid (low pH) the color of the hydrangea will automatically tend toward shades of blue and/or purple.