The english oak (Quercus robur) is a deciduous tree native to Europe. It is a very long-lived tree; the oldest known specimens have been living for more than a thousand years. It is commonly represented in European mythologies as a symbol of strength, longevity, nobility, morale, and knowledge.
I. Appearance and Characteristics
Quercus robur, the pedunculate oak, is a species of flowering plant in the beech and oak family, Fagaceae. It is a large tree, native to most of Europe and western Asia, and is widely cultivated in other temperate regions. It grows on soils of near neutral acidity in the lowlands and is notable for its value to natural ecosystems, supporting a very wide diversity of herbivorous insects and other pests, predators and pathogens.
Quercus robur is a deciduous tree up to 40 m tall, with a single stout trunk that can be as much as 11 m in girth (circumference at breast height) or even 14 m in pollarded specimens. Older trees tend to be pollarded, with boles (the main trunk) 2-3 m long. These live longer and become stout than unpollarded trees. The crown is spreading and unevenly domed, and trees often have massive lower branches. The bark is greyish-brown and closely grooved, with vertical plates. There are often large burrs on the trunk, which typically produce many small shoots. Oaks do not produce suckers but do recover well from pruning or lightning damage. The twigs are hairless and the buds are rounded (ovoid), brownish and pointed.
The leaves are arranged alternately along the twigs and are broadly oblong or ovate, 10-12 cm long by 7-8 cm wide, with a short (typically 2-3 mm) petiole. They have a cordate (auricled) base and 3-6 rounded lobes, divided no further than half way to the midrib. The leaves are usually glabrous or have just a few simple hairs on the lower surface. They are dark green above, paler below, and are often covered in small disks of spangle gall by autumn.
Flowering takes place in spring (early May in England). It is wind-pollinated. The male flowers occur in narrow catkins some 2-4 cm long and arranged in small bunches; the female flowers are small, brown with dark red stigmas, about 2 mm in diameter and are found at the tips of new shoots on peduncles 2-5 cm long.
The fruits (acorns) are borne in clusters of 2-3 on a long peduncle (stalk) 4-8 cm long. Each acorn is 1.5-4 cm long, ovoid with a pointed tip, starting out whitish-green and becoming brown, then black. As with all oaks, the acorns are carried in a shallow cup which can be distinctive in identifying the species. It is an “alternate bearing” species, which means that big crops of acorns are produced every other year.
The species most likely to be confused with it is sessile oak, which shares much of its range. Quercus robur is distinguished from Q. petraea by its leaves having auricles at the base, the very short petiole, its clusters of acorns being borne on a long peduncle, and the lack of stellate hairs on the underside of the leaf. The two often hybridise in the wild, the hybrid being Quercus × rosacea.
Turkey oak is also sometimes confused with it, but that species has “whiskers” on the winter buds and deeper lobes on the leaves (often more than half way to the midrib). The acorn cups are also very different.
Pedunculate oak is a long-lived tree of high-canopy woodland, coppice and wood-pasture, and it is commonly planted in hedges. When compared to sessile oak, it is more abundant in the lowlands of the south and east in Britain, and it occurs on more neutral (less acid) soils. It is rare on thin, well-drained calcareous (chalk and limestone) soil. Sometimes it is found on the margins of swamps, rivers and ponds, showing that it is fairly tolerant of intermittent flooding.
II. How to Grow and Care
Sunlight
The English oak grows best in full sunlight, though it can tolerate some shade. In humid climates, full sun is more necessary to prevent fungal problems.
Temperature and Humidity
This tree is best suited for zones 5 to 8. The tree can grow in sheltered spots in zone 4, though freezes can be damaging or even deadly. This tree does not like humid conditions, and if planted in such a region make sure to give it good air circulation and full sun to prevent fungal diseases.
Watering
English oak trees prefer regular irrigation, especially when young. A good 1-inch soaking each week, through a combination of rainfall and irrigation, will keep young trees happy for the first two or three years. An English oak can, however, tolerate relatively mild drought once it becomes established. Mature trees can get by nicely on a monthly deep watering.
Soil
Quercus robur is able to tolerate a range of soil pH from acidic to slightly alkaline (pH 4.9 to 8.0). For optimal growth, find a location with soil that stays moist but still provides good drainage.
Fertilizing
English oak can survive and thrive without supplemental fertilization. But if you wish to give them extra nutrients you can add some of 12-6-6 (N-P-K) fertilizer. This has more of a ratio of nitrogen than phosphorus and potassium. Also, consider the natural environment of oaks. They grow where there is lots of forest litter. This forest litter acts as natural mulch that breaks down into organic matter and humus. So one way to give some natural nutrition is to spread mulch by your oak trees. They will love the extra organic matter.
Pruning
Branches should be pruned to avoid moist pockets or where heavy branches may fall on people or buildings. Avoid having branches that grow with leaves tight together or pressed against buildings. If rain collects in these pockets then molds and fungi can attack. English oak love having their leaves dry out in a well ventilated breeze.
To ensure that no danger occurs from the brittle hardwood branches, make sure that heavy branches do not hang over walking paths or outbuildings. Also, do not let children play near oaks in a thunderstorm as they are susceptible to falling branches and lightning strikes.
Propagation
English oak does not transplant well, thanks to the long taproot, so vegetative propagation is not common. In addition, most named varieties are created by grafting, which means that rooting a stem cutting is not likely to produce an identical tree.
Propagation is most often done by planting the ripened seeds (acorns), which are usually not produced until the tree is at least 20 years old.
How to Grow from Seed
As a member of the white oak group, English oaks do not require a cold stratification period before the acorns are planted. Be aware, however, that most named cultivars are grafted trees, so the acorns likely produce trees with differing characteristics. But if you want to try propagation of a pure species tree by seed, it is easy to do:
Simply gather three or four acorns that have fallen from an English oak tree (fallen acorns will be fully ripe). Fall is a standard planting time, but the acorns can be stored in the refrigerator over the winter and planted in the spring.
Plant the group of acorns in the location where you want the new tree to grow, at a depth about three times the diameter of the acorn. Orient the acorns lengthwise in the planting hole. Water weekly until the seeds germinate and sprout. This can take as little as one week.
If more than one seedling sprouts, clip off the weaker stems, giving preference to the seedling that is healthiest. Water the seedling weekly for the first two years, until it is well established.
Overwintering
If planted within its established hardiness range, English oaks require little in the way of winter protection once they are mature. Rake up leaves as winter sets in to prevent fungi from overwintering. Young trees may benefit from protecting the trunks with tree wrap or plastic tree guards for the first two winters in zone 4 landscapes. It is best to water the tree well going into winter, but then reduce watering during the winter months.
Pests and Diseases
Common Pests and Plant Diseases
This oak tree species is noted to be resistant to sudden oak death, a disease that plagues some other oak species. The biggest problem English oak faces is the unattractive presence of powdery mildew. Anthracnose can also be an issue in wet conditions, causing leaf drop. Regular fertilization will help to combat canker diseases if they prove to be a problem. Some possible diseases that do not need to be treated include shoestring root rot, leaf blister, and leaf spots.
Common Problems
Other than powdery mildew, a non-life-threatening fungal disease that frequently occurs in humid climates, English oak is largely free of cultural issues and is less susceptible to the common diseases that can be problems with other oak species. The most common complaint is that the tree is just too massive and low-hanging for most residential landscapes. When it overwhelms a yard—which may well occur with older trees—it can be sharply pruned to raise and thin out the canopy to allow sunlight down into space.
III. Uses and Benefits
English oak grows luxuriously and vigorously, creating shelter and visual appeal in a short period of time. It is thus a popular choice for new landscaping projects in both commercial and residential settings. Pine trees make good neighbors for this oak, with Rhododendrons and hardy ferns beneath.
Find Where to Buy the Best English Oak (Quercus robur)
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