French hydrangeas are one of the most favorite plants among Southerners. We love to grow, clip and share them with friends and family. In the warm days of summer, big balloons of blues, pink, purple, and white blooms seem to float up like magic from the lush green foliage of these shrubs. French hydrangeas, or mopheads, with their globelike, brightly colored flowers, are what most of us recall growing in our grandmother’s yard. Lace cap hydrangeas, a sister to the mopheads, have flowers that seem to float in flat, delicate looking clusters above the foliage. Their appearance is light and airy, beckoning bees and butterflies to the garden.
Both mopheads and lacecaps create a beautiful show in the garden as well as in cut arrangements. To guarantee a bounty of beautiful blooms for years to come, follow these tips for planting and caring for both new and established hydrangea plants.
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Simply the best. When buying a French hydrangea at your local nursery look for more than just pretty flowers. Choose a full plant with equal branching on all sides. In late spring and early summer, the stems should be covered with fat buds or flower heads that are ready to open—or opening. Leaves should be bright green and not drooping (an indicator that the plant may not have been watered regularly). Some hydrangeas have been developed and grown in greenhouses to bloom quickly and out of season in order to be sold for Mother’s Day. While beautiful, they may not be garden-hardy selections and, once in the ground, will have trouble with the seasonal growth cycles.
Good soil. French hydrangeas love moist, well-drained soil with lots of organic matter, such as peat or chopped leaves. If you have hard clay soil, spend some time amending it with organic matter to give your new plants a fighting chance. Mulch plants to help keep roots cool and moisture consistent—especially important when the late summer heat ramps up. Try to maintain the mulch depth at about 3 inches to conserve moisture and regulate soil temperature. Keep the mulch away from the base of the plant by about four inches to maintain airflow and prevent rot.
Proper sunlight. In the South, hydrangeas should be planted in locations with plenty of morning sun and afternoon shade. (These shrubs have few pests but can get spider mites if planted in full sun.) During periods of high temperatures, hydrangeas, particularly mopheads, are inclined to droop from heat stress, so be sure and water consistently. Hydrangeas also love a coastal setting, where breezes help dissipate the heat.
Plant well. Water your plants as soon as you get them home, saturating the soil in the pot. Plot out the placement before planting. Most French hydrangeas can be spaced 3 to 4 feet apart, but check the tag to see how wide your selection will grow. Dig a hole that is two to three times as wide as the pot but the same depth. Remove the plant from its container, and set it in the center of the hole. Gently loosen the sides of the root-ball with your fingers. Fill the hole with a mixture of half original soil and half compost. Mulch and water regularly to help establish your plant.
Accessorize them. French hydrangeas look great in generous sweeps, but if you really want to make your borders sing, pair them with hostas in the foreground. Both love partial shade and plenty of water. Other pairings: Use evergreens such as camellias and purple loropetalums as backdrops. Ferns and variegated monkey grass work great in the foreground.
Remember to prune. French hydrangeas that flower once, such as 'Nikko Blue,' bloom on last year's growth. Prune just after flowering in summer. Repeat-blooming French hydrangeas, such as 'All Summer Beauty' and 'Big Daddy,' flower on both old and new growth. These can be pruned almost anytime.
Protect from cold.You need to protect your hydrangeas in the winter if your area gets freezing winter temperatures. Leaves, wood mulch and/or straw are good options to insulate your plants. Mound the mulch or leaves around your plants at least 12” high to protect the flower buds that will bloom early next year. In the spring, wait until all danger of frost has passed before uncovering to ensure beautiful blooms. If your hydrangeas are planted in a container, bring the entire container into your garage or a cool basement for the winter months, and follow the same steps as garden-planted hydrangeas. Water lightly throughout the winter months since they will not receive moisture from snow and rain.
Change the color. Sometimes, the hydrangea you bought as blue changes color and blooms pink the following year. Your hydrangea is simply responding to the soil pH. Blue flowers are produced in acid soil (pH 5.5 and lower), and pink flowers are produced in alkaline soil (pH 7 and higher). You can change the color by adding aluminum sulfate around your hydrangeas to acidify the soil. Add lime to make your soil more alkaline. Some selections are less affected by soil pH than others. White-flowering ones will stay white.
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Spring is just around the corner, so start making plans now for this year's vegetable garden.