In Georgia, bigleaf hydrangeas, Hydrangea macrophylla, sometimes known as French, Japanese, or snowball hydrangeas, are grown both as landscape and florist plants. Bigleaf hydrangeas are frequently bought as gift plants from florists and can be moved to the landscape for yearly blooms. By modifying the soil pH, homeowners can alter the color of flowers from pink to blue or from blue to pink.
Two Main Groups
In the nursery industry, bigleaf hydrangeas come in more than 500 different cultivars. They can be split into two main categories: hortensias, which have huge flower clusters resembling snowballs, and lacecapes, which often have flowers with fairly flat tops, fertile blooms in the center, and showier sterile flowers on the periphery.
Location
Bigleaf hydrangea prefers moist, well-drained soil, morning light, and afternoon shade. Don’t plant it in exposed, hot, dry areas. Winter and late spring can cause cold damage to the buds, so be ready to offer some winter protection by wrapping the plant in an old sheet, blanket, or cardboard box when the temperature drops below freezing. Additional effective cold protection is offered by a cylinder of chicken wire surrounded by leaves.
Bigleaf hydrangea is a great patio plant that is simple to cultivate in containers. The ability to bring the plant indoors on a chilly night is another benefit of growing it in a container.
Planting
Prepare the soil over a large area if at all possible. Apply 50 pounds of decomposed organic material per 10 square feet and thoroughly work it with a tiller or shovel into the top 8 to 12 inches of soil. Organic matter keeps nutrients and water in the soil and protects plants from stress caused by changes in soil moisture from wet to dry.
Before the plant is established, don’t fertilize (4 to 8 weeks after transplanting). Since Georgia’s soils tend to be acidic, the first blossom color will probably be blue.
After transplanting, make sure the root ball’s top is flush with the soil’s surface and give it a good drink of water. To retain moisture and manage weeds, add 3 to 5 inches of an organic mulch to the soil’s surface, such as pine straw, pine bark, or fallen leaves.
Fertilization and Watering
Throughout the growing season, bigleaf hydrangea responds to many sparing fertilizer applications. It is advised to apply a general-purpose fertilizer, such as 8-8-8 or 10-10-10, at a rate of 1 pound (2 cups) per 100 square feet in the months of March, May, and July. When fertilizing, it is not required to remove the mulch; however, watering soon after application will help the fertilizer dissolve and go into the soil.
Bigleaf hydrangea is a water-hungry plant that does best in landscape zones with moderate water requirements. When the plant starts to wilt in the absence of rain, water it. Avoiding plant stress during the spring, when the blooms are developing, is especially crucial.
Flower Color
According to research, the presence or absence of aluminum compounds in the flowers is the real cause of color variation. The color is blue if aluminum is present in the plant. If it’s absent or only minimally present, the blooms are pink, and if it’s there, the color is “in between.”
Through influencing the amount of aluminum in the soil, soil pH indirectly influences flower color. Aluminum is typically more accessible to the roots in soil that is acidic (pH 5.5 or lower). Alkalinity (pH 7.0 or above) in the soil reduces aluminum availability and increases the pinkness of the blooms.
Distribute 1/2 cup of wettable sulfur per 10 square feet and water it in to gradually turn pink flowers blue. Spread one cup of dolomitic lime per 10 square feet and soak it into the soil to turn the flowers pink. The effects of this treatment on flower color could not be visible for a year.
Through liquid soil drenches, you can change the color of your flowers more quickly and easily. In March, April, and May, saturate the soil around the plant with 1 tablespoon of alum (aluminum sulfate) dissolved in 1 gallon of water to make the blossoms blue, or perhaps more blue. In March, April, and May, soak the soil surrounding the plant with a solution of 1 tablespoon of hydrated lime in 1 gallon of water to turn the blossoms pink. Avoid getting the mixture on the leaves to prevent foliar damage.
Failure to Flower
Bigleaf hydrangeas can have problems with flowering failure. This may be brought on by winter damage to the flower buds, overly-shady plant growth, an excess of nitrogen fertilizer, or untimely pruning. Pruning throughout the late summer, fall, and winter will eliminate prospective blossoms since bigleaf hydrangeas develop their flower buds in the late summer for the next year.
Pruning
When the bigleaf hydrangea’s blossoms start to fade, prune it. To promote branching and fullness, remove blossom heads and head back other shoots as appropriate. Avoid pruning after August 1 since flower buds for the following season will start to grow in late summer.
After a difficult winter, it may be necessary to prune plants to remove damaged foliage. The removal of winter-damaged leaf is healthier for the health of the plant and its aesthetically pleasing appearance, even though it will promote vegetative growth at the expense of flowering.
Propagation
Softwood cuttings collected in the early summer can be used to multiply bigleaf hydrangeas. Choose terminal cuttings from shoots that are not in bloom. A minimum of three leaves and a length of 3 to 5 inches should be present on each cutting. Make a little angle cut at the node (where the leaves are joined), then dip the cut end in a rooting hormone and plant it in a moist growing medium. To prevent wilting and dehydration, propagators frequently cut off the top half of each leaf. While the cuttings are rooting, keep them wet and in a shaded environment.
Layering is another method of bigleaf hydrangea propagation in the landscape. This is accomplished by excavating a trench close to the plant and bending a branch downward into the trench. At the point where the limb touches the ground, use a knife to carefully remove a narrow band of outer bark that is about an inch broad. After that, bury the limb in dirt, leaving 6 to 12 inches of the growth at the tip exposed. The new plant should be ready for transplantation the following winter if layering is done in the summer.
Early spring is a good time to separate clumps of mature, older hydrangeas with a shovel. A cluster that has been there for a while can produce many plants.
For More Information
On hydrangeas, there are several top-notch books accessible from publishers and online. Dr. Michael Dirr, a former professor at the University of Georgia, is the author of the book Hydrangeas for American Gardens. Both online and in bookstores, it is widely accessible. Additionally, the U.S. National Arboretum offers a fantastic online resource for choosing and growing hydrangeas. To learn more, visit www.usna.usda.gov/Gardens/faqs/hydrangeafaq2.html.
Associate in public service and coordinator of the state’s master gardening program; consumer ornaments
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When should hydrangeas be pruned?
Depending on which group the plant belongs to, the timing and extent of pruning are determined:
Advice on Pruning for Group 1:
- As the days get shorter and the weather gets colder in the late summer and fall, buds for the following year’s blooms start to form.
- Typically, removing dead, diseased, or damaged branches is all that is required to preserve shape, size, and a healthy plant. Otherwise, gentle pruning ought to be practiced.
- In the summer, trimming should begin as soon as flowering ends, but no later than August 1. Pruning should not be done in the fall, winter, or spring because you risk removing fresh buds.
- Tip-pruning the branches in the spring as the leaves begin to appear can promote more numerous, smaller flower heads as opposed to fewer, larger flower heads.
Advice on Pruning for Group 2:
- On the growth of the current year, flower buds form.
- Early in the spring, as the leaves are starting to emerge, prune.
- Just above a node, prune branches back by half to a third.
- After that, prune any fragile or spindly branches.
- Minimal trimming encourages huge, strong bushes with many of tiny flower heads in H. arborescens. Hard pruning between 12 and 18 inches from the ground, or even all the way down, will result in fewer but larger flower heads that may flop if unsupported.
- For H. paniculata, remove the surrounding smaller wood while leaving the larger stems in order to establish a sturdy foundation.
Pruning may be connected to flower head size. Shoots will grow more vigorously and flower heads will be bigger and fewer with more rigorous trimming. Smaller but more numerous flower heads may result from less aggressive or tip pruning.
Consideration of hydrangeas’ mature size is the best piece of advise. Place them in a location where they won’t outgrow and won’t need a lot of pruning to keep them in check. Hydrangeas don’t need to be pruned precisely or often; as long as dead wood is removed, they will remain healthy and continue to develop and bloom.
What occurs if your hydrangeas aren’t pruned?
If and when you prune is the key to happy, healthy hydrangea flowers. Of course, fertilizing and offering the ideal environment have a lot to recommend them. However, if you don’t prune properly, your efforts will be in vain. Deadheading is not the same as trimming. Pruning refers to more drastic cutting to preserve shape or remove dead growth. However, feel free to discard spent blossoms or cut fresh ones to use in arrangements.
Hydrangeas can bloom on either fresh wood or old wood, depending on the species. The wood from which they blossom determines whether and when to prune.
Old wood-blooming hydrangeas do not require pruning and benefit from it. They’ll blossom more abundantly the next season if you leave them alone. But feel free to deadhead or gently thin. Just keep in mind that while new growth may appear, it won’t bloom until the following season. In our region, four different species blossom on aged wood. Additionally, they are not limited to the hues displayed here.
Climb using suckers. On your wall or trellis, resist the desire to remove the dormant growth.
The flower heads are more conical in appearance, and the leaves are large and resemble oak leaves. It’s a pleasant surprise for a hydrangea when its leaves turn reddish-orange in the fall.
They are very comparable to lacecap types, but smaller and with more compact leaves.
Pruning should be done in late winter or early spring on hydrangeas that bloom on new wood. Trim back to two feet to prune to shape. The next season’s blossoms are produced by strong, fresh growth that is encouraged by trimming. In our region, there are two types that bloom on fresh wood. They are also not restricted to the colors displayed.
Oakleaf variants are not included in cone-shaped blooms. Keep the blooms on throughout the winter to provide interest; even dried out, they are quite lovely.
regarded as a wild kind. They often have smaller blooms and leaves than Bigleaf variants and are completely white. They enjoy full sun and can grow very tall.
Knowing whether or when to prune now will help you avoid the disappointment of a hydrangea that doesn’t blossom. Don’t forget that a robust shrub will produce more gorgeous blossoms if it has well-draining soil and good organic fertilizer. Come on in, and we’ll show you where to go to develop your green thumb.
When pruning hydrangeas for the winter?
It’s not necessarily necessary to severely prune your hydrangeas (Hydrangea spp.) before putting them to bed for the winter. Depending on the cultivar, hydrangeas can be grown in USDA plant hardiness zones 3 through 9, with each variation having different pruning requirements. Before you grab the shears, you must identify the type of hydrangea to know how far back to cut it for the winter.
Tip
Depending on the variety, hydrangeas can bloom on either old or new wood. Old-wood blooming hydrangeas need to be pruned just after the flowers fade in the late summer, whereas new-wood blooming hydrangeas should be pruned in late winter before new growth begins.
How are bigleaf hydrangeas prepared for the winter?
Protecting flower buds is the aim of winter hydrangea care. The simplest approach is to pile 12 inches or so of mulch made of chopped-up leaves or bark around the base of the plant. After the ground freezes in the late fall, set the mulch pile there. Plants can then be exposed in the spring, when the temperature starts to stay above freezing.
Big leaf hydrangeas reach what height?
The traditional hydrangeas that you see on magazine covers and in florist bouquets are bigleaf hydrangeas, often known as mopheads or French hydrangeas. They are a huge shrub that can reach a height of 10 feet and a spread of 10 feet. They prefer the shade and wilt in too much scorching, direct sunlight. The soil pH can be changed to produce blooms in the colors of white, pink, blue, purple, or red. Look for the “Endless Summer” hydrangea collection, “Nikko Blue,” and “Tokyo Delight” variations.
How much should hydrangeas be pruned back in the fall?
Trimming season for hydrangeas that bloom on new wood runs from late fall through early spring. This group includes smooth and peegee forms, which function well whether they are pruned lightly, to the ground, or not at all. In order to maintain a compact stature and luxuriant flowering, Peegee hydrangeas are frequently pruned into trees with one or two main stems that are between 15 and 30 feet tall.
Smooth hydrangeas can be pruned all the way to the ground; however, the more frequently they are cut, the less able their stems are to withstand the weight of their huge blooms. Smooth hydrangeas grow in mounds that are 3 to 6 feet tall and wide. When the plants are pruned to leave between 18 and 24 inches of growth, a woody base forms that helps the stems support the pompom blooms more effectively.
Should I cut off Brown hydrangea blooms?
Your hydrangea shrubs’ blossoms appear to be withering or turning brown. No need to worry—this is merely a signal that it’s time to deadhead—remove the blossoms from the plant.
Deadheading hydrangeas doesn’t cause any damage to the plants at all. Flowering shrubs stop producing seeds when the spent blooms are removed, and instead focus their efforts on developing their roots and leaves. You will be doing your hydrangeas a favor by deadheading because this strengthens and makes plants healthier.