Oakleaf hydrangea also referred to as Hydrangea quercifolia is a species of flowering plant in the family Hydrangeaceae. It is native to the Southeastern United States, in woodland habitats from North Carolina west to Tennessee and south to Florida and Louisiana. The plant can grow up to 8 feet high and between 4 to 6 feet wide.
Oakleaf hydrangea flowers appear in elongated, cone-shaped clusters referred to as inflorescence (flower heads consisting of a group or cluster of flowers arranged on a stem). The inflorescences consist of a combination of showy sterile and inconspicuous fertile flowers. Once established, though, they bloom fairly predictably when given proper care.
Generally, the flowers of Oakleaf hydrangea are produced in July in terminal clusters of 6 to 12 inches long. The flowers begin life as a creamy white, but during the following month, they change to a light and then rosy-pink color as they mature. In the fall, the foliage of deeply lobed, oak-like leaves, turn bronze, crimson or burgundy (if planted in a sunny location with a little shade). The more direct sun the plant receives, the more the flower colors fade.
Oakleaf hydrangeas are low maintenance gorgeous shrubs. They have no serious insect or disease problems. Aphids and spider mites are occasional visitors and there is some susceptibility to leaf blight and powdery mildew. The plant can be used for mass plantings, hedges, mixed shrub borders, as backdrop or accent plant. Its flowers are popular for cutting and drying.
|Oakleaf hydrangea, oak-leaved hydrangea
|Deciduous flowering shrub
|4 to 8 feet tall
|Full sun, partial shade
|Rich, well-drained soil
|5.0 to 6.5 (Acidic)
|May to July
|White transitioning to purplish-pink
|5 to 9 (USDA)
How To Grow And Care For Oakleaf Hydrangea
Oakleaf hydrangea thrives marvelously in full sun or partial shade. Plant the hydrangeas in an area that receives full morning sun, with a little afternoon shade especially in hot climates. Alternatively, plant this shrub where they get dappled sunlight all day long. The plant won’t perform well in dry, sunny sites and blossoms may look faded or scorched. In full shade, the plant might fail to bloom.
In northern areas of United States, Oakleaf hydrangeas do well in full to light shade whereas in the southern areas, the shrub grows effectively with morning sun and protection from intense afternoon rays.
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The Oakleaf hydrangea is easily grown in organically rich, medium moisture, well-drained, slightly acidic soil. Oakleaf hydrangea grows best in a soil PH of between 5.5 and 6.5. You can lower the soil PH by adding sulfur, peat moss, sawdust or dried leaves to acidify the soil. To raise the soil PH, you can add dolomitic lime into the soil.
More importantly, avoid growing hydrangea in soggy soils or areas with heavy clay as this can affect proper growth of the Oakleaf hydrangea. In areas with soggy soil or heavy clay, take time to amend your soil at planting time with manure or compost. This is very important as it helps improve water penetration and drainage, loosens compacted soil and encourages good root growth.
When choosing a site for your Oakleaf hydrangea, be it in the ground or in a container, be sure to use soil that is rich in organic matter.
The good thing about Oakleaf hydrangea is that it can thrive in much dryer and sunnier locations than other types of hydrangea such as mophead and lacecap hydrangeas. Oakleaf hydrangea often wilt when temperatures goes up. They lose moisture through transpiration faster than their roots can take it up.
Water newly planted hydrangeas at least twice a week or as needed to keep the soil evenly moist but not soggy. Water the established hydrangeas at least once a week. During prolonged droughts in the summer or if they are in poor soil or are un-mulched they will require regular watering (daily).
Temperature And Humidity
Hydrangeas prefer moderate to warm weather in spring and summer, when they are actively growing. Temperatures around 70 degrees Fahrenheit (70oF) in the day and just below 60 degrees Fahrenheit (60oF) at night are ideal. During the fall bud development stages, Oakleaf hydrangeas require six weeks of temperatures below 65 degrees Fahrenheit for the buds to set.
Oakleaf hydrangeas are fairly heavy feeders. If not planted in soil rich in organic matter that is well mulched, they will appreciate some fertilizer in the spring or fall. Use a slow acting 10-10-10 granular fertilizer. Apply the fertilizer around the Oakleaf hydrangea once in the spring and once in the summer. Always take care to avoid excess fertilizer application as too much fertilizer encourages lush, green growth instead of flowers.
Pruning is the removal or reduction of parts of plant that are not requisite for growth or are no longer visually appealing. Oakleaf hydrangea do not require routine pruning. Prune the older growth from Oakleaf hydrangeas after the shrub blooms. Oakleaf hydrangea blooms on old wood; if you prune it in winter or spring, you are likely to remove the flower buds and prevent blooming for the season.
Take one-third of the total growth or less to avoid cutting off next year’s blossoms. A light trim is more beneficial to Oakleaf hydrangeas, they do not necessarily require extensive pruning to keep their shape. Prune from all sides to keep the leaf Oakleaf hydrangea looking balanced. Remove any dead or disease ridden branches as close to the main stem as possible.
Mulch is simply a protective layer of material that is spread on top of the soil. Mulches are generally organic in nature and include grass clippings, straw, bark chips, pine needles, crop residues, sawdust, chopped leaves etc. Reason for applying mulch include conservation of soil moisture, improving fertility and health of the soil, reducing weed growth and enhancing the visual appeal of the area. Apply a 3-inch layer of organic mulch across its entire root area, keeping it several inches away from plant foliage. The mulch layer decomposes over time, adding valuable organic matter to the soil around the shrub.
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How To Plant Oakleaf Hydrangea
To plant the Oakleaf hydrangea, dig a hole twice as wide as the root ball of your plant and deep enough that you will be able to set the crown at the same depth it was in its container. Add compost to the hole to break up clay soil and provide good drainage. Place your plant in the hole and backfill with a 50/50 mixture of soil and compost, pressing the soil firmly over the root ball.
Water you plant thoroughly and add a layer of mulch to keep roots cool. Oakleaf hydrangeas require some significant moisture until they get established, but in future seasons, these hardy natives are quite drought tolerant.
Common Diseases Of Oakleaf Hydrangea
Aphids are generally tiny insects; aphids can create a big problem when too many of them decide to infest your Oakleaf hydrangea. They often cluster on the underside of the leaves and suck the nutrient-rich sap. This has a potential of making the leaves to turn yellow, brown or curl. If appropriate measures are not taken on time, the whole plant gets infested and dies before getting a chance to fully bloom. Spraying your plant with insecticidal soap can wash off and kill the aphids.
Spider mites tend to eat the outer edges of Oakleaf hydrangea leaves, making the leaves turn brown around the edges. If appropriate control measures are not taken, with time, the leaves develop multiple brown spots and begin to wilt. New blooms may appear discolored or stunted. Spraying the plant with insecticidal soap or organic insecticides is usually the ideal way of getting rids of these mites from your plant.
Botrytis blight is very common especially when the season is wetter than normal. It causes flowers to develop brown spots that spread to other branches of the plant. The blooms eventually turn fully brown and curl up, then become covered with a fluffy mold. Usually, pruning off the affected stems and parts quickly can help stop the disease. Also, spraying the hydrangea with fungicide can be very effective in helping to prevent the spread of the mold.
Powdery mildew is one of the easier diseases to identify on Oakleaf hydrangea as its symptoms are quite distinctive. Your infected Oakleaf hydrangea will display white powdery spots on the leaves and stems. The symptoms are commonly observed on the upper sides of the leaves and the bottom side as well. Spraying the Oakleaf hydrangea with fungicide can be very effective in helping to prevent the spread of the powdery mildew.
Root rot is typically a fungal infection that enters the plant through the roots, especially when the soil is overly wet. The common signs of root rot include blooms and leaves turning brown, curling up and falling of the plant. Fungicides are not effective against root rot, but digging up the Oakleaf hydrangea and disposing it off can help prevent the spread of the disease to other plants.
Frequently Asked Questions (FAQ)
How Much Sun Does Oakleaf Hydrangea Require?
In northern zones, Oakleaf hydrangeas do well in full to light shade whereas in the southern zones, the shrub grows effectively with morning sun and protection from intense afternoon rays.
How Long Does It Take For Hydrangeas To Bloom?
Oakleaf hydrangeas started from May through September will bloom the following summer.
What Side Of The House Do You Plant Oakleaf Hydrangeas?
Oakleaf hydrangea can grow effectively in dappled or part shade. The southern side of the house is often ideal place to plant the Oakleaf hydrangeas.
How Big Does Oakleaf Hydrangea Get?
The Oakleaf hydrangea grows to a height of 4 to 8 feet and spreads to 4 to 6 feet at maturity.
Do Oakleaf Hydrangea Lose Their Leaves In Winter?
As a deciduous shrub, it is normal for the Oakleaf hydrangea to lose their leaves in the late fall to winter. As soon as the spring days warm up, you should see the buds starting to swell and to leaf out.
Why Is My Oakleaf Hydrangea Not Blooming?
A lack of blooms is usually caused by improper pruning methods, inadequate water, and over-application of fertilizer or lack of sunlight.
Will Dear Eat Oakleaf Hydrangea?
Oakleaf hydrangea and climbing hydrangea in particular are not appetizing to the dear and other animals. If you are living in an area with high population of deer, then planting Oakleaf will be very ideal.