Ginkgo

Ginkgo: how do you recognise it?

Habit

Tree of 15–30 m, often narrow and sparse when young, broader later with irregular branches.

Leaf

Fan-shaped, 5–8 cm wide, often notched in the middle; veins forked, with no midrib. Long stalk, often in clusters on short side shoots. Autumn colour butter yellow.

Bark

Grey-brown, becoming coarsely fissured with age.

Seeds

Female trees only: yellow, plum-like seeds that smell strongly of butyric acid (rancid butter) once they have fallen.

Male or female

Ginkgo has separate male and female trees. A seedling often only shows its sex after 20 years or more, so it is better to buy a grafted or cutting-grown male tree.

Flowering: April · Pruning: November–March

Why grow it?

• Unmistakable fan-shaped leaves that turn butter yellow in autumn.
• Almost no pests or diseases, and it tolerates air pollution and urban conditions.
• A tree with a story: a living fossil from the age of the dinosaurs.
• There are slender columnar forms and dwarf forms for smaller gardens.

Ginkgo: where does it grow best?

• Full sun.
• Almost any well-drained soil; no waterlogging.
• The species grows 25 m tall and 8 m wide or more: for a large garden, a park or a street. For a smaller garden there are slender columnar and dwarf forms.
• Copes with urban conditions, paving around its base and air pollution better than most trees.

Light

Full sun

Legal basis

Any garden soil

Moisture

Normal

Size

25 m tall, 8 m wide

Hardiness

Throughout Belgium, no protection needed

Goes well with

• Japanese maple: Red or orange autumn colour next to the butter-yellow leaves of the ginkgo.
• Katsura tree: Another Asian tree with superb autumn colour; its fallen leaves smell of caramel.
• Crocus: Flowers in early spring under the still-bare crown.

Good and bad companions

Goes well with

• Tolerate the shade under this tree: oregon grape, rhododendron, oleaster, japanese skimmia, garden privet, camellia, laurustinus, box-leaved honeysuckle

Ginkgo: when and how to plant it?

1. Plant from November to March; a pot-grown tree can also go in in spring.
2. Buy a named male cultivar (grafted or grown from a cutting): then you won’t get smelly seeds.
3. Dig a large planting hole, plant at the same depth as before and firm the soil.
4. Put a stake on the windward side and tie the trunk loosely; remove stake and tie after 2–3 years.
5. Water generously after planting and in dry spells during the first few years.

Care

Watering

In dry spells during the first two or three years; after that it copes.

Feeding

Not needed; a little compost in spring helps a young tree get going.

Patience

For the first few years after planting it barely grows: that is normal, it is making roots first.

Autumn

The yellow leaves often all fall within a few days: rake them up or leave them as a mulch.

Tip: Always buy a named male cultivar, especially near a patio or driveway: the seeds of a female tree smell and make the ground slippery.

Ginkgo: when to prune it?

Pruning months: November–March.

When: Dead, diseased and broken branches can be removed at any time of year. If pruning is needed, do it during winter dormancy (November–March).

How:

• Hardly needs pruning; grows slowly and forms a nice shape on its own.
• On a young tree, only remove a competing leader and crossing or damaged branches.

Caution: Prune little and never hard: a ginkgo grows slowly and takes years to replace a branch you have sawn off.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Sowing

Wearing gloves, remove the flesh from the seeds and sow them in a pot outdoors in autumn. Only after many years will you know whether you have a male or a female tree.

Cultivars

Male cultivars and dwarf forms are grafted or grown from cuttings by the nursery.

Ginkgo: how does it get through the winter?

Hardy throughout Belgium: no protection needed.

• Fully hardy.
• In winter you can see the short, knobbly side shoots on which the clusters of leaves appear in spring.

Diseases and pests

• Smelly seeds: In autumn female trees drop yellow seeds that smell of rancid butter. Buy a male cultivar; under a female tree, pick up the seeds regularly, wearing gloves.
• Slow start: A young tree almost stands still for the first few years. Water in dry spells and be patient.
• Pests and diseases: Hardly any: ginkgo is one of the healthiest trees you can plant.

Through the year

• January: Formative pruning during winter dormancy, if needed.
• February: Formative pruning still possible; plant in mild weather.
• March: Last month for pruning; planting.
• April: New clusters of leaves appear.
• June: Water young trees in dry spells.
• October: Butter-yellow autumn colour; seeds fall under female trees.
• November: The leaves fall within a few days; planting and pruning seasons begin.
• December: Remove dead branches.

What can you use it for?

Garden and landscape

Tough street and park tree that tolerates air pollution; golden-yellow autumn colour.

Food and drink

In East Asia the roasted kernels are eaten, but they are poisonous in larger amounts.

Caution: Female trees bear foul-smelling seeds: choose a male tree for streets or gardens.

Did you know?

• Botanically not a broadleaf but a gymnosperm, related to the conifers. A ‘living fossil’ from the age of the dinosaurs.
• In Hiroshima a few ginkgos survived the atomic bomb of 1945; they are still standing today.
• The leaves often all fall within a few days, sometimes almost overnight.
• In Hiroshima a few ginkgos survived the 1945 atomic bomb 1 to 2 km from the blast. They are still standing today.
• Like ferns, ginkgo has sperm cells that swim. The Japanese researcher Sakugoro Hirase discovered this in 1896.