Hydrangeas are a southern delight. Here are a few tips I have picked up through the years for growing these beautiful flowering shrubs.
Knowing our planting zone
One of the best starting places for successful hydrangeas is knowing our growing zone and the first and last frost dates. According to the USDA, we are in zone 7a with 213 growing days from mid-April until the first frost in late October. The best time of year for planting hydrangeas is in the spring after the last frost or in the fall before the first frost.
Where to plant?
Most Hydrangeas grow best in partial sun. They like full sun in the morning and some afternoon shade to protect them from the midday sun.
When to prune?
For pruning hydrangeas, the general rule of thumb is if it flowers before June, prune right after flowering. These flowering shrubs flower on old growth made the previous year. The time to prune flowering hydrangeas is immediately after the flowering is finished, to give the plant time to develop new growth before winter arrives.
Watering
Most hydrangeas thrive in rich, porous, pretty moist soils. After planting, be sure that they get plenty of water in the first year or two, especially during drought and hot months. In the late fall, cover the base of the plant with bark mulch, leaves, compost, straw, or pine needles to help them have protection from the elements over the winter.
Soil acidity and hydrangea color
A late friend of mine threw her coffee grounds at the base of her blue hydrangeas outside her kitchen door, and they were the prettiest things you have ever seen. The coffee grounds alter the pH of the soil. It is a good idea to have your soil tested by your local extension office to determine the pH of your soil. Blue hydrangeas thrive in more acidic soils, while white, pink, and red hydrangeas are best suited for alkaline soils. Check with your nursery for directions to amend your soil with aluminum sulfate or limestone after having it tested according to your hydrangea color. It takes several weeks to months to alter the color of your blue or pink and red hydrangeas. White hydrangeas stay the same color and will not change color. Best results will come by leaving your hydrangeas to establish themselves for two years before attempting to alter the colors.
Blue
An old friend of mine always told me to throw a couple of handfuls of Epsom salts at the base of blue hydrangeas in the spring to make them bluer. Evidently, this is good for plants as Epsom salt is composed of magnesium and sulfate. For a more measurable approach and increase the soil's acidity for deeper-blue flowers: Apply a solution of diluted aluminum sulfate 3-4 times per year after the plant starts to grow in the spring. Carefully follow package directions or ask your nursery for help with the proper proportions.
Pink
To encourage blue to pink blooms, increase the alkalinity of the soil. In the spring or fall, spread ground limestone and water well. Consult your nursery for the proper ratio of limestone to the surface area around your hydrangeas, as excessive alkalinity will cause leaves to be yellow. It is much easier to change blues to pink than pink to blue, and some cultivars are easier to alter than others.
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