Let us introduce the elegant Styphnolobium japonicum, the perfect tree to add refined volume to your garden thanks to its airy leafage.
Sophora japonica key facts
Botanical name – Styphnolobium japonicum, formerly Sophora
Common Name – Japanese pagoda tree
Family – Fabaceae
Type – slow-growing tree
Height – 60 feet (20 meters)
Breadth – 45 to 60 feet (15 to 20 m)
Exposure – sun to shade
Soil – deep, not chalky
Hardiness – hardy
Foliage – deciduous
Flowering – end of summer for older specimens
Presenting Sophora japonica
Native to Asia, the pagoda tree mostly stands out thanks to its large, airy leafage. Leaves can reach 8 inches long (20cm) and are composite leaves: each has 7 to 17 deep green oval leaflets that are a mat gray color underneath. The summer blooming is not a stunner at all – it’s kind of hidden by all the leaves. Moreover, only older, mature specimens actually bear flowers. Whitish yellow in color, the flowers are gathered into hanging clusters.
The elegant Sophora japonica also exists in a weeping form (S. japonica ‘Pendula’). This cultivar is much smaller. It has a particularly appealing bearing that completely transforms the appearance of the garden. Branches hang over, creating an intimate hiding place underneath. In winter, the leaves fall and the lovely umbrella-like branches are revealed.
Planting the Japanese pagoda tree
A major advantage of Sophora japonica is that it doesn’t have very stringent requirements to grow. Though it can adapt to nearly any growing environment, you’ll have the best results with deep soil – the less chalky, the better – and lots of warmth and full sun.
When to plant it?
As for most trees and shrubs, success is most guaranteed when planting Sophora japonica in Fall. This makes settling in easier. However, thanks to its adaptivity, it’s possible to set it up in Spring.
How to plant Styphnolobium japonica ?
- Dig a trench that’s rather on the deep side, about 1½ feet deep (50 cm).
- Add soil mix or compost in the hole, and loosen the bottom and sides up with a spading fork to mix the amendment into the soil.
- Remove the sophora tree from its pot, and break the clump up. The goal is to tease the root ball open.
- If ever the tree was sold to you as a “bare root” tree (not in a pot), dip the tangle of roots in root dip before laying it down in the hole.
- Hammer a stake into the ground nearby, without damaging any roots.
- Backfill the hole, pressing the soil down as you do so.
- Tether the trunk to the stake with a loose staking belt.
Caring for Styphnolobium japonica
Over the first year, help young specimens grow by topdressing the soil around the base. Just spread a little soil mix or mature compost around the tree at the beginning of Spring. It might be necessary to perform structural pruning in years 2 and 3, to guide your Sophora japonica. Afterwards, all that’s needed is to eliminate old wood and branches that are too low.
Multiply your pagoda tree by sowing its seeds in pots, in a cold frame. Before planting, soak them for a few hours in a glass of water.
Diseases and pests
A naturally resistant tree, Styphnolobium japonica isn’t very vulnerable to either pests nor diseases.
Use in landscaping
A majestic tree, S. japonica will look nicest in large gardens and parks. Since it grows rather large, it’s usually planted as a standalone, eventually surrounded by a flower bed once it gets a bit taller.