Sessile oak.

At a glance

Care level

Moderate

Plant type

Tree

Light

Full sun to partial shade

Indoor light

Direct sun

Water

Every 7 to 14 days

Mature size

20 to 40 meters

Growth rate

Slow

Hardiness

USDA 4 to 8

Bloom time

Mid to late spring

Care

Plant this tree in a spot with plenty of space for its root system to expand. Keep an eye out for leaf discoloration or stunted growth which might signal poor soil drainage. It is a hardy tree that handles wind well once it is established.

Watering

Young trees need consistent moisture until they are established.

Feeding

Apply a balanced slow release fertilizer in early spring if growth seems sluggish.

Pruning

Remove dead or crossing branches during the dormant winter season.

Repotting

Only necessary for container grown specimens that have become root bound.

Soil

Well drained acidic soil

Soil pH

4.5 to 6.5

Temperature

-25 to 35°C

Humidity

40 to 80%

Drought tolerance

Moderate

Lifespan

Long lived, often exceeding 500 years.

Deer and rabbits

Moderate

Safety

People

The leaves and acorns contain tannins which can cause digestive upset if ingested in large quantities.

Children

Acorns pose a potential choking hazard for small children if left within reach.

Contact allergens

The bark and leaves are generally safe, but some individuals may experience mild skin irritation from contact with sap.

Airborne allergens

The windborne pollen is a common seasonal allergen for many people.

Edibility

Acorns contain tannins that must be leached thoroughly before they are safe to consume.

How to identify it

• Leaves have rounded lobes
• Acorns sit directly on twigs
• Deeply fissured grey bark
• Broad spreading canopy

Height

20 to 40m

Spread

15 to 25m

Leaves

green, yellow, brown, deciduous

Flowers

yellow, green, 0.5 to 1cm

Fruit

brown, Autumn

Problems to watch for

• Oak mildew · A fungal infection that causes white powdery patches on leaves.
• Oak processionary moth · Caterpillars that feed on leaves and can cause health issues for humans.

Growing it

Propagation

seed

When to plant

Spring, Autumn

Overwintering

No special protection is needed as it is fully hardy. Ensure the soil remains well drained to prevent root rot during wet winters.

In containers

Not suitable for long term container growth due to its massive size.

Plant shade tolerant understory species that enjoy acidic soil to mimic a natural woodland floor.

Grows well with

• Holly · It thrives in the dappled shade provided by the oak canopy.
• Bluebell · These woodland bulbs bloom before the oak leaves fully emerge.

Similar species

• Pedunculate oak · It is very similar but has stalked acorns and prefers heavier, nutrient rich soils.

Science

Family

Fagaceae

Genus

Quercus

Order

Fagales

Class

Magnoliopsida

Native range

Europe and parts of Western Asia.

Conservation

It is not currently threatened, but it is a key species in protected ancient woodland habitats.

It thrives in well drained, acidic soils and is highly adapted to the cooler, wetter climates of Western Europe.

Value to wildlife

larval host plant, food source for birds and mammals

Pollinators

bees, beetles

Uses

timber production, shade tree, wildlife habitat, parkland specimen

Taxonomy resolved against GBIF.

Questions people ask

How fast does it grow?

It is a slow to moderate grower, especially in its early years.

Does it need a lot of water?

Once established, it is quite tolerant of dry spells but prefers consistent moisture.

Where the name comes from

The name Quercus is the classical Latin name for oak, while petraea refers to its preference for rocky or stony ground.

Good to know

• Sessile oaks are known for their long lifespans, often living for several hundred years.
• The name sessile refers to the acorns being attached directly to the twig without a stalk.
• This tree is a vital part of the ecosystem, supporting hundreds of different insect species.
• It is closely related to the pedunculate oak, but prefers well drained, acidic soils.