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Oakleaf hydrangea was first described by the American naturalist William Bartram in the late 18th century. But she took her place in the gardens of the New and Old Worlds much later, since the first experience of growing an ornamental crop was unsuccessful. Only at the beginning of the 20th century, when the agrotechnics of the oak-leaved hydrangea was understood, was it able to enter the design of ornamental plantings, almost completely displacing its relative, the macrophylla. This is a beautiful and elegant plant with good weather resistance.
Description of oak hydrangea
Hydrangea oakleaf (Hydrangea Guercifolia) is a deciduous shrub with a height of 150 to 200 cm. The trunk of the culture is straight and hardened near the roots. The growth of oak-leaved hydrangea is up to 50 cm per year. The root system is pivotal, with several large leads located at a depth of up to 40 cm.
A feature of this species are its leaves of a characteristic “oak” shape. Their size can reach up to 25 cm, they have sharp and jagged edges. The pattern of the veins of oak-leaved hydrangea is embossed and clear.
Large seven-lobed leaves of the oak-leaved hydrangea have pubescence and are able to change color.
During the season there are two color changes of the vegetative part of the plant. In early spring, the foliage of the oak-leaved hydrangea is dark green. From August, the process of repainting it into a rich red color begins, which changes to dark burgundy in September. In fact, only green leaves are completely pubescent; as it changes, the hairs remain only on the underside.
The flowers of the oak-leaved hydrangea are collected in large panicle inflorescences.
Most often they have a conical shape and consist of many white flowers with a diameter of up to 30 mm. Their smell is sweetish, barely perceptible. The flowering of oaky hydrangea is long: it begins in mid-June and lasts until the end of September.
Varieties of oak-leaved hydrangea with photos and names
There are about a dozen popular plant varieties. All of them are used in landscape design.
Harmony
This variety of oak-leaved hydrangea has an interesting difference in the anatomy of the flowering part. In other respects, it repeats the original culture.
The inflorescences of the Harmony variety have a greater number of flowers and a length increased to 30-32 cm.
The mass of hydrangea flowers is so significant that the stems can sag.
snow-white domes
Similar to Harmony, it has more flowers in the inflorescence. Moreover, its shape may not be elongated, but spherical. The rest of the culture is identical to the original oak-leaved hydrangea.
The main difference between the Snow-White Domes is the round shape of the inflorescences.
Burgundy
One of the most beautiful varieties. He has few differences, but all of them, as it were, “enhance” the characteristic features of the oak-leaved hydrangea. So, for example, the coloring in autumn at Burgundy is the brightest. Young leaves, on the contrary, are rich green. Shoots golden yellow.
The leaves of Burgundy are most reminiscent of oak in shape – there are rounded lobes, there are no hairs.
Flowering lasts from late June to August. The petals are white or cream at first, then change to pinkish.
Tennessee clone
It has relatively small numerous inflorescences. Their length rarely exceeds 10-12 cm.
The flowers of the Tennessee clone are cream, they have a characteristic petal shape, narrowed at the base.
The number of inflorescences on a bush can exceed 30-40 pieces. Which, on average, is twice as much as any other variety.
Snow Queen
This variety of Oakleaf Hydrangea has been bred to produce large flowering parts. It has large massive flowers (up to 5 cm in diameter) and inflorescences. The leaves are relatively thin, almost without pubescence.
The mass of inflorescences at Snow Queen is very large, so the branches with them are pressed to the ground
The color of the petals of this variety can be white or pinkish. Sometimes different colors are found on the same plant.
Oakleaf hydrangea in landscape design
The culture is able to fulfill all the roles of a large and beautiful bush with abundant flowering. It can be used as the center of a composition or to give accents to a particular object. In mixborders, oak-leaved hydrangea is usually used, shortening the shoots to 1,2-1,5 m.
The shrub can also be used to create continuous monoculture plantings.
You can often find oak-leaved hydrangea as a hedge or high border.
However, there are some nuances. They relate to the fact that, despite the good winter hardiness of the oak-leaved hydrangea, some of the buds can freeze from frost. Moreover, this is observed even at relatively low temperatures. And, since the generative buds of the oak-leaved hydrangea are updated every two years, it may happen that some bushes will be left without flowers, which will significantly worsen the look of the garden.
Winter hardiness of oak-leaved hydrangea
Despite the almost subtropical origin, the plant has good resistance to frost. Most varieties of oak-leaved hydrangea have a frost resistance zone of 4, that is, they are able to withstand temperatures down to -35 ° C.
Some varieties have much lower resistance (6th zone, that is – 23 ° C). In any case, when purchasing seed, you need to make sure that the culture is suitable for a particular climate.
Planting and caring for oak hydrangea
Planting a plant is best done in the spring, in early or mid-April. If there is a desire to do this in the fall, then October will be the best month.
Selection and preparation of the landing site
Culture feels best in partial shade. The quality and fertility of the soil does not play a special role for the oak-leaved hydrangea. There are only two main requirements for the site, but both are critical:
- the level of acidity pH in the range of 5,0-6,5;
- absence of wetlands.
The site practically does not need preliminary preparation, the holes are dug the day before planting material is planted, watered abundantly and nothing else is done with them.
Rules of landing
It is best to plant oak hydrangea in the morning. A substrate is placed in the dug holes, consisting of equal proportions of the following components:
- garden soil;
- peat;
- sand;
- humus
Next, a seedling is installed on the resulting mixture and the soil is added to the edges of the hole. After planting, a little watering is done, the soil is loosened and mulched with sawdust or peat.
Watering and top dressing
The culture has enough moisture from natural precipitation. Therefore, the oak-leaved hydrangea is watered only during a drought. At the same time, the frequency of watering is from 1 to 2 times a week, depending on the moisture content of the upper soil layer. Under one bush requires up to 10 liters of water.
Feeding is done every month, starting in May. In total, they should be applied 4-5 times. The first consists of nitrogenous fertilizers (carbamide in the amount of 50 g per 1 sq. M), the rest – from potassium-phosphorus. In the latter case, it is best to use 30 g of superphosphate per 1 sq. m.
Pruning oak hydrangea
Starting from the age of two, to give the plant a decorative effect, it is pruned. In the spring, it is sanitary in nature – damaged and diseased branches are removed, as well as those that grow inside the crown.
Before the start of bud break, the crown is shaped into a semicircle
In autumn, it is necessary to cut off only the faded parts of the plant. This procedure is done immediately before sheltering the bush for the winter.
Shelter for the winter of oak-leaved hydrangea
Despite the rather high frost resistance of the plant, its buds can freeze even at relatively low temperatures (about -20 ° C). So that the plant does not lose its decorative effect next year, it must be covered.
Annual and biennial bushes should be spudded, covered with sawdust and covered with polyethylene
Adult specimens of the oak-leaved hydrangea are bent to the surface of the soil and covered with sawdust, spruce branches or fallen leaves. A plastic film is placed on top.
Sometimes the following technique is used: the branches are tied, and a metal frame is installed above the bush, which is filled from the inside with fallen leaves. As in other cases, polyethylene is pulled over it from above. As soon as the snow melts, the shelter is removed.
In more detail, the shelter of the oak-leaved hydrangea for the winter on the video:
Reproduction
The plant is propagated by all available methods:
- seeds;
- cuttings;
- division of the bush;
- layering.
Unlike many ornamental crops, seed propagation in oakleaf hydrangea is quite effective and fast; material is sown in seedlings in seedlings in February. Peat, sand and garden soil are used as a substrate.
The first sprouts hatch in March. Seedlings are grown all summer, and then planted in open ground.
The division of the bush is applicable for adult plants with more than a dozen large stems. It is allowed to separate the root with a shovel without digging it out of the ground.
The most effective propagation by cuttings. They are harvested in July from the stems of the previous year, which have at least three pairs of leaves.
The lower leaves are cut off, and the cuttings themselves are placed in water in which a few drops of Epin are dissolved.
The roots appear in about a month, after which the cuttings are planted in individual containers, where they grow in room conditions until April of the next year, when they are planted in open ground.
Diseases and pests
Oakleaf hydrangea is resistant to most diseases, but sometimes it is affected by fungal infections. The most dangerous for the culture is gray rot. It affects plants of any age.
Symptoms of rot – the appearance of gray spots on the leaves
Usually the cause of the disease is a violation of the conditions of the plant – high humidity or stagnant water at the roots. Treatment consists in spraying the culture with copper-containing preparations and changing the irrigation conditions.
Of the pests, spider mites most often attack oak-leaved hydrangea. But here the reason is completely different – excessive dryness.
Small spider mite most often hides on the underside of the leaves
In the fight against this pest, you need to use acaricides: Aktellik, Aktara or Fitoverm. But, as in the case of diseases, the main thing in treatment is to adjust the conditions of the plant.
Conclusion
Oakleaf hydrangea is a beautiful culture with large inflorescences and decorative leaves. It can be used for various design solutions in temperate gardens and parks. The culture has good immunity to pests and diseases. To preserve the decorative effect, it is recommended to cover the plant for the winter.
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