Blue globe-shaped hydrangea need acidic soil to maintain their color.
Hydrangeas are lush, deciduous flowering shrubs that have been grown for hundreds of years and come in dozens of varieties. Hydrangea macrophylla, which blooms in shades of pink, blue and sometimes green, originated in Japan. Mophead and lacecap are the common names for the two varieties of hydrangea macrophylla, and this still-popular landscape hydrangea is the one common to old home sites in the southern United States. Its colors are determined by the pH level of the soil, with blue flowers growing from acid soil and pink flowers thriving in a more alkaline environment. While not typical, green blooms do occur. Does this Spark an idea?
Instructions
1. Hydrangea macrophylla colors vary from blue to pink and sometimes green.
Identify the type of hydrangea growing in your yard by consulting a local nursery owner or by comparing blooms to photographs on Internet sites or in gardening books. The limelight hydrangea is a relatively new and hardy hydrangea variety that has smaller leaves, but large, upright bright green blooms that turn to deep pink by fall. The plant's color is not affected by the soil pH. Hydrangea macrophylla is the only hydrangea variety with the ability to bloom blue.
2. Test the pH level in your soil with a do-it-yourself kit or by sending it to your state university's local cooperative extension office for a small testing fee. A soil test will save the guesswork involved in determining the acidity of your soil. A pH level below 6.5 is recommended to grow blue hydrangeas.
3. Fewer daylight hours can affect the color of the hydrangea bloom.
Observe the blooming cycle of your hydrangea. If your plant blooms late in the season, a green hydrangea bloom can be perfectly normal. Green hydrangea blooms are usually a combined result of Mother Nature and hydrangea hybridization, and primarily occur as the days get shorter and the light that gives the plants the energy to produce colored flowers diminishes. If your blue hydrangea stubbornly stays green for a season or two, however, your only choice is to chalk it up to a horticultural mystery and be patient.
4. Promote blue blooms on your hydrangea macrophylla by watering the plant twice yearly with a diluted aluminum sulphate and iron sulphate solution. Mix a quarter-ounce of each chemical in a gallon of water and water your hydrangea with no more than two gallons of this mixture in the spring before blooming, and in the fall after the plant finishes blooming. Hydrangeas need frequent regular watering as well.
