How to Grow and Care for Japanese Pagoda Trees

A Beautiful Tree That is Worth The Wait

Summer Foliage of the Japanese Pagoda Tree

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The confusing name, Japanese pagoda tree (Styphnolobium japonicum) of this Chinese native is likely the only thing that will make you question this stunning tree. Japanese pagoda tree are perfect if you live in an urban setting, are looking for a flowering shade tree, or are planning a Japanese garden. The Japanese pagoda tree is without a doubt a beautiful tree that you will want to add to your garden design if you have space and the patience to devote to the payoff that comes when it is ready to show off. 

Botanical Name Styphnolobium japonicum
Common Name Japanese pagoda tree
Plant Type  Deciduous tree
Mature Size 50 - 75 ft. tall, 50 - 75 ft. wide
Sun Exposure Full sun
Soil Type Well-drained sandy loams
Soil pH Adaptable
Bloom Time July
Flower Color Creamy white
Hardiness Zones 4-8 (USA)
Native Area  China
Toxicity Toxic

Japanese Pagoda Trees Care

The Japanese pagoda trees has outstanding ornamental value, can be grown in a wide variety of conditions, and is, for the most part, easy to maintain. The only two drawbacks are waiting for the tree to produce flowers, which can take ten years, and that the wood is sometimes weak, which can be alleviated with structural pruning. (And if you want a tree that flowers faster, the cultivar Styphnolobium japonicum ‘Regent’ will produce much earlier at six years.)

One important thing to look for when selecting a Japanese pagoda tree is its trunk form. Be sure to select a tree with a single leader or solitary trunk that splits into branches at 45 to 60o angles from the trunk. Branches that form a narrower angle will eventually need to be pruned so that a weak crotch is not formed. Shopping around a little bit will save a lot of work down the road.

The ease of maintaining this uncommon tree, plus the floral payoff and its ability to handle adverse conditions, makes it worth a look. It is usually available at most smaller nurseries in its hardiness zones.

Tip

When shopping for the Japanese pagoda tree, you may see it listed as Sophora japonica. This synonym is an out-of-date name often used in error by horticulturalists and nurseries instead of its correct scientific name. You will be buying the same tree as Styphnolobium japonicum.

Light

Japanese pagoda trees need full sun to thrive, and you will see a vast difference in bloom production in anything less. Providing partial sun will not harm the health of the tree, but it will affect its ornamental value, which is likely why you will choose this tree in the first place.

Soil

One desirable attribute of the Japanese pagoda tree is that no matter the soil conditions or the setting of the soil, it adapts. This positive is one of the main qualities that make this tree attractive as a shade tree. It grows amazingly well in tree pits, in parking squares, and as street trees where there is a large amount of pollution in the air and surface, soil compaction, and poor soils.

Ideally, the soil for this tree would be a well-drained sandy loam rich in nutrients, but it will adapt to almost any environment except wet soggy soil.

Water

Once your Japanese pagoda tree has established itself, it is very drought tolerant. It will, of course, perform better as an ornamental and produce more blooms with supplemental watering. However, no supplemental water is needed if you want to be environmentally friendly or practice water-wise gardening. During its first season, water your Japanese pagoda tree or any tree using the standard of two to three gallons of water per inch of its trunk diameter. After the first year, how you want to water your tree depends on the light and soil conditions, but the tree will tolerate some drought.

Temperature and Humidity

Pagoda trees are not incredibly fickle when it comes to temperature. It is readily frost hardy down to -25 degrees Fahrenheit when mature, but it can be damaged by frost when young.

Fertilizer

Unlike other trees that generally would not call for fertilizer, supplemental fertilizer is often beneficial. Remember that no blooms will be created for at least 10 years, so giving the tree fertilizer in those first 10 years is wasting nutrients. When your Japanese pagoda begins to blooms, you will want to use a fertilizer with an NPK formulation with high phosphorous as your fertilizer of choice. A 10-30-10 is an excellent mix for flowering trees. 

Is the Japanese Pagoda Tree Toxic?

Parts of the Japanese Pagoda are toxic, though traditional medicine in China has been using the tree for thousands of years. The pods are the toxic element of the tree while the rest of the tree, specifically the flowers and leaves, is what has been traditionally used. It is recommended that you not try to harvest from your own Japanese pagoda tree; instead, if interested, you should buy from a trusted and reputable source.

Symptoms

The pods should not be ingested by humans or pets. Symptoms of ingestion include facial swelling and light headedness. Contact poison control if a human or animal has consumed the pods.

Pruning

Pruning your Japanese pagoda tree will be the most labor-intensive maintenance you will have to do when caring for your tree. However, if you buy good nursery stock and prune well within the first three or four years of your tree’s life, your workload will be drastically reduced going forward.

After the first year, once your tree has been established during the late fall or early winter, you will want to do your first pruning.

The pruning you are going to be doing is purely structural. You will attempt to give your tree a single leader, with solid secondary limbs perpendicular to the leader at 45 to 60o angles from the trunk. Cut off any interior branches that are at acute angles that are less than 45o. The following year, continue this effort and proceed onward doing this until you have a rounded crown formed.

Once the tree becomes too large to continue, you may need to call in a licensed arborist to follow through on the work you started. It will be much cheaper for your service because of your work and the tree you picked initially.