Oakleaf Hydrangea: Varieties, Location And Care
The oakleaf hydrangea inspires with its name-giving oak-leaf-shaped leaves and white flowers. We show you what you should consider when planting and caring for this species of hydrangea.
The oakleaf hydrangea is a special eye-catcher in the garden with its lush flower panicles. The decorative leaves, whose shape is reminiscent of that of the American red oak, take on a pretty coloration in autumn.
Oakleaf Hydrangea: Origin, Characteristics And Flowering The Time
The oakleaf hydrangea (Hydrangea quercifolia), also called oak hydrangea, is a species of the hydrangea family (Hydrangeaceae). Originally it comes from the southeast of the USA and thrives in dry forests and steppes.
The oakleaf hydrangea grows as an upright shrub, about 1 to 2 m high. It also becomes about 1 to 2 m wide, in the age through runner formation partly even wider. Between July and September its flowers open, which are arranged in conical to roundish, about 15 cm large flower panicles. They are composed of sterile specious flowers and fertile flowers.
The specious flowers usually have 4 to 5 petals and are 3 to 4 cm in size. At the beginning of flowering, they are pure white, later they turn reddish. The fertile flowers lie close together between the specimen flowers and are less conspicuous. While the sterile flowers serve to attract insects, it is the fertile flowers that provide food for the pollinators with pollen and nectar.
The special characteristic of the oak-leaf hydrangea, which also gives it its name, is the striking shape of its leaves. The 10 to 20 cm long, about 15 cm wide leaves are firing lobed and remind strongly of the leaves of the American red oak (Quercus rubra), especially since they also turn red, dark red, or even purple in autumn.
In summer, the semi-evergreen foliage is deep green on the upper side and grey-green on the underside. The upper side is wrinkly, the underside is felt-hairy. Also, the shoots have a reddish felt at first, which decreases with increasing age.
Oakleaf Hydrangea: The Most Beautiful Varieties
The varieties of the oak-leaf hydrangea differ in flower structure, autumn coloration, and growth height. The following varieties are extremely ornamental and will particularly enrich your garden:
The Hydrangea quercifolia ‘Alice’ grows 1.5 to 1.8 m high and 0.5 to 1 m wide. It forms large numbers of lush white and later pale pink flower panicles. The foliage appears at first in a strong green and contrasts beautifully with the bright white flowers. Later, the leaves take on a pretty autumn coloration.
The variety ‘Snowflake’ forms double blooms and is therefore a special eye-catcher. It grows 0.8 to 1.5 m high and 0.6 to 1.2 m wide. The large, oak-leaf-shaped leaves turn reddish to bronze in autumn.
The variety ‘Ruby Slippers’ grows somewhat more compact. It reaches a growth height of 1 to 1.5 m. Its flower panicles first turn pink and then dark red during flowering.
Planting Oak Hydrangea: Location And Time
Oakleaf hydrangeas can be planted all year round. However, the condition is that no frosts are to be expected on the days around the planting.
The hydrangeas prefer a sunny to a semi-shady and sheltered location in the garden or on the balcony. The soil should be fresh to moist and humusy.
On too nutrient-rich sites, the shoots will only ripen less before frost, so that they can be affected by frost damage more often. Large doses of fresh compost before planting are therefore not appropriate for oak-leaf hydrangea.
The oakleaf hydrangea is sensitive to waterlogging, which is why a drainage layer, for example of gravel, should be applied in case of compacted or very heavy soil. Such a layer is also absolutely necessary for potted plantations.
Compared to other hydrangea species, which are very sensitive to high lime content in the soil, oakleaf hydrangea is lime-tolerant. The soil pH-value of oak hydrangeas may also be slightly higher than that of garden hydrangeas, for example. It should be in the neutral to the weakly acidic range. Nevertheless, oakleaf hydrangea is also calcification-tolerant and should therefore not be limed under any circumstances.
Once you have found the right place, you can plant the oak-leaf hydrangea. Dig a sufficiently large planting hole in the flower bed. It should be about twice as large as the root ball. If the soil in your garden does not meet the above requirements, you can mix it with sand to increase the permeability of the substrate and mix it in mature compost.
Alternatively, you can buy peat-free potting soil and mix it with sand in the above-mentioned ratio to obtain the optimal substrate. Bio universal soil is ideal for this purpose – it contains all the important nutrients in a balanced ratio. At 6.1 to 6.9, the pH value is weakly acidic to the neutral range and is therefore suitable for oakleaf hydrangea.
Put a small part of the substrate back into the planting hole and place the planting ball in the middle of it. By loosening the root ball slightly with your hands or with a spade, you will cause small injuries to the roots, which will stimulate the growth and branching of the roots.
Then fill the planting hole completely with a substrate, press the soil, and pour on generously. If you want to plant several hydrangeas next to each other, you should keep a planting distance of about 2 meters.
The oakleaf hydrangea is also suitable as a potted plant for the balcony or terrace. Choose a sufficiently large planter with a drain hole so that excess water runs off during watering and no waterlogging can occur. To avoid the formation of waterlogging, shards of clay should be placed on the bottom of the pot.
Care Of The Oakleaf Hydrangea
As with all hydrangea species, a good water supply is a basic prerequisite for the successful development of hydrangea plants. Especially young plants have to be watered daily. Apart from occasional fertilization and the care cut, however, no special care measures are necessary.
Watering and fertilizing oak hydrangeas
Newly planted hydrangeas must be watered daily so that they can grow well. In dry, hot periods of summer, you should also water oakleaf hydrangeas once a day, and in pots maybe even twice a day. Although Oak Hydrangeas are more tolerant of lime than other Hydrangea species, you should preferably use rainwater with a low lime content.
Oakleaf hydrangeas love cool, moist soil. This is most easily achieved by a mulch layer of leaves or bark mulch. Such a layer serves as protection against evaporation and keeps the moisture in the soil longer.
Especially hydrangeas in pots should be fertilized yearly and preferably in spring so that they can start well into the growing season. Organic hydrangea fertilizer is ideal for this. With its long-term effect, it reliably supplies your hydrangeas with all necessary nutrients and prevents typical deficiency symptoms and diseases. Work in the fertilizer flat and, if necessary, cover it additionally with a mulch layer of leaves or similar so that it starts to work quickly.
Cutting oakleaf hydrangea
Oakleaf hydrangeas have beautiful, upright growth. They can be pruned if necessary, but even without pruning, the plants develop magnificently. Only the shoots and flower panicles, which have frozen or dried up over the winter, should be removed in spring. Cut off the dried flowers with clean garden shears just above the new flower buds.
Oakleaf hydrangeas hibernate
Oakleaf hydrangeas are hardy in our region. When buying them, it is best to select well-hardened plants from specialist shops. Plants from tree nurseries are often preferable to plants from garden centers. Well-hardened hydrangeas are winter-hardy down to -23 °C, as long as they are not exposed to cold and damp winter winds. Young shoots also survive temperatures down to -10 °C without damage.
However, if you want to be on the safe side, you can cover the soil around the plant base of the hydrangea with leaves or fir branches. This prevents its roots from being damaged by frost. Hydrangeas in pots are somewhat more endangered due to the small volume of soil: It can happen that the whole pot freezes through. Therefore, in late autumn you should cover the plant pot with plant fleece or jute bags and, if necessary, place it in a protected place, such as a house wall.
Propagating oakleaf hydrangeas
Oakleaf hydrangeas can be propagated using cuttings. These are cut in early summer. Cut annual, flowerless shoots from the plant and divide them into pieces about 10 to 15 cm long. The leaves are then removed except for the upper pair of leaves and the cuttings are placed at least 5 cm deep in planters filled with seed soil.
Low-nutrient organic herb and seed-soil are suitable for this purpose. Mixed with at least a third of sand, it forms the right substrate for the cuttings. The substrate should be moistened daily. In a bright place without direct sunlight and at a temperature of about 15°C, the cuttings can take root and grow into new hydrangea young plants.