Incredibly pretty when in full bloom, the Japanese Cherry Blossom tree, Prunus serrulata, is primarily grown for its profuse and showy spring blossoms.
While the Prunus serrulata species is rarely sold in commerce, its many beautiful cultivars are extremely popular with gardeners, in particular the Kanzan cherry, which is responsible, along with the Yoshino cherry (Prunus x yedoensis) for the outstanding pink floral display each spring in Washington, D.C.
I. Appearance and Characteristics
Prunus serrulata or Japanese cherry is a species of cherry tree that grows naturally in Japan, China, Korea, and Vietnam, and it also refers to a cultivar produced from Prunus speciosa (Oshima cherry), a cherry tree endemic in Japan. Historically, the Japanese have developed many cultivars by selective breeding of cherry trees, which are produced by the complicated crossing of several wild species, and they are used for ornamental purposes all over the world. Of these, the cultivars produced by complex interspecific hybrids based on the Oshima cherry are also known as the Cerasus Sato-zakura Group.
Prunus serrulata is a small deciduous tree with a short single trunk, with a dense crown reaching a height of 7.9–11.9 metres (26–39 ft). The smooth bark is chestnut-brown, with prominent horizontal lenticels. The leaves are arranged alternately, simple, ovate-lanceolate, 5–13 cm long and 2.5–6.5 cm broad, with a short petiole and a serrate or doubly serrate margin. At the end of autumn, the green leaves turn yellow, red or crimson.
The flowers are produced in clusters of two to five together at nodes on short spurs in spring at the same time as the new leaves appear; they are white to pink, with five petals in the wild type tree. Its fruit, the sakuranbo, has differences from the Prunus avium in that sakuranbo are smaller in size and more bitter in taste; the sakuranbo is a globose black drupe 8–10mm in diameter. Owing to their bitter taste, the sakuranbo should not be eaten whole, raw; the seed inside should be removed and the fleshy part preserved.
Because of its evolution, the fruit developed merely as a small, ovoid cherry-like fruit, but it doesn’t develop past a small amount of fleshy mass around the seed; as P. serrulata was bred for its flowers, its fruits do not enlarge the way cherry varieties bred for their fruit do.
II. How to Grow and Care
Sunlight
Cherry blossom trees grow best in full sun, with at least six hours of direct sunlight a day. Some varieties will tolerate some shade. In areas prone to droughts, be sure to plant the tree in a location where it will get partial shade, and mulch around the base to retain moisture.
Temperature and Humidity
Most cherry blossom trees need winters that aren’t too harsh. Cool temperatures of about 45°F are essential for the dormancy period that allows them to blossom in the spring. Warmer temperatures during late winter may bring earlier spring blooms. Humidity doesn’t impact cherry trees and they can tolerate Southern summers. However, they do require consistent moisture and need more frequent watering during hot, dry months.
Watering
Water young trees weekly, increasing to twice weekly during dry weather to help them get established. After the first two seasons, watering every two weeks is sufficient, with more watering during droughts. Long soakings, enough to soak the ground all around the roots, are better for these trees than quick showers.
Soil
Cherry blossom trees can adapt to a variety of soil types, including sandy and clay options, but they prefer moist, well-drained acidic soil. Mulch around the base of the tree, up to but not touching the trunk, to help it retain moisture without encouraging too much water collection.
Fertilizing
Japanese cherry likes to be fertilized. A sufficient amount of fertilizer will ensure that it grows healthily and bears fruit. Organic fertilizer is usually used for its base fertilizer. When applying fertilizer, dig a circular trench around the external circumference of the tree crown, at a depth of 38 cm and a width of 28 cm. Apply the fertilizer evenly throughout the trench, then backfill the soil.
Fertilizer should be applied twice a year, the first time prior to blooming, to supply nutrients for the flowers, and the second time when the fruit is growing larger, to supply nutrients for fruit growth and to increase the yield.
Planting Instructions
You can purchase japanese cherry saplings in garden centers. Pay attention to two things before planting. First, choose an area of the garden that has a lower altitude to plant your Japanese cherry. This will help it to acquire enough water because its roots are shallow. Additionally, apply sufficient base fertilizer before planting it, mostly organic fertilizer. Once planted, remember to water it soon after, until the water on the surface of the soil stops draining away. When this happens you have provided sufficient water.
We generally do not sow seeds to propagate japanese cherry because the seeds need to undergo post-ripening effects. This means that the seeds are not yet mature when they are harvested. It is only after a period of special treatment that the seeds can complete their biochemical processes and reach the condition of being mature seeds that are able to germinate.
Pruning
Generally speaking, very little pruning is necessary for Prunus serrulata cultivars other than removing damaged branches. In fact, the more you prune, the more likely you are to allow fungal diseases to take hold.
If you need to prune, do so after the tree flowers. Always sterilize your cutting tools after each cut. Some limbs can grow too quickly and heavy for the base, so it’s best to prune away the heavy branches as needed.
Propagation
Most ornamental cherry trees are created by grafting branches from a selected cultivar onto the hardier rootstock of a wild cherry. Propagating them yourself is an uncertain prospect, as the plants resulting when you root stem cuttings will not have the hardy rootstock. The shape, size, and overall rigorousness can be quite different than your parent plant.
Cuttings should be taken from semi-hardwood branches during the summer months. If you wish to experiment with propagation by stem cuttings, here’s how to do it:
- Choose a branch that has two to four leaf nodes and leaves.
- Using sterilized pruning shears, cut off a 4- to 8-inch section at a horizontal angle and remove the leaves from the bottom two-thirds of the branch.
- Dip the cutting into the rooting hormone.
- Push the cut end into a mixture of half perlite and half sphagnum peat moss. Pat down the soil around it.
- Place a loosely secured plastic bag over the container, then move the pot to a sunny location.
- Mist the cutting twice a day to keep the soil moist.
- After two to three months, gently tug on the cutting to see if it’s rooted. If there’s resistance, let the cutting grow until the roots have filled the pot.
- When ready, transfer the plant to a gallon-sized container filled with potting soil. Move it outside to let it acclimate to the temperatures for a week before transplanting the tree to a location with full sun.
How to Grow From Seed
Most cherry seeds need cold stratification before planting; this involves exposing seeds to a period of cold temperatures to mimic winter which helps trigger germination. Wrap cherry seeds in a damp cloth, place them in a ziplock bag, and put them in the refrigerator for about 10 weeks.
During early spring, plant the prepared seeds in full sun about 2 inches deep into the soil, then cover with a layer of mulch to retain moisture.
Potting and Repotting
Most ornamental cherry trees are too large for container growing, but it’s possible to grow Japanese flowering cherry trees in containers or even as bonsai plants if you choose a compact cultivar. Potted cultivars of P. serrulata require regular pruning. Such plants can make excellent patio specimens.
Use ordinary commercial potting soil in a large, deep, well-draining container (terra-cotta pots are best to aid in drainage). Repotting will be difficult, so start with the largest container possible.
Some experts recommend replacing a good portion of the potting soil every two to three years. Feed the plant with a good controlled-release fertilizer each spring. A potted tree will need to be watered regularly—several times a week in hot weather.
Overwintering
Over much of their hardiness range, Japanese flowering cherries require no winter protection. However, gardeners in the northern part of the range (zone 5) may want to mulch the ground around young trees with a thick layer of dry straw or leaves to protect the roots from cold over the winter months. Clean up fallen leaves and other debris to prevent fungal diseases and insect larvae from overwintering to reappear in the spring.
Pests and Diseases
Common Pests and Plant Diseases
Gardeners who want to enjoy the beauty of a Japanese flowering cherry should be prepared to spend considerable time treating pests and diseases in most years, but the spring bloom is worth it for many. In fact, their susceptibility to a number of pests makes most specimens short-lived. Careful care can keep the plant healthy enough to resist many problems, but don’t be surprised if your tree succumbs after 15 to 20 years.
Peach Tree borers are a notable pest problem for cherry trees. For borer control, most experts simply advise keeping the tree vigorous (and therefore less susceptible to borer attack) by providing adequate irrigation and fertilizer. You can use spray pesticides formulated for peachtree borer to treat current infestations.
Other small pests that trouble this tree are scale insects, spider mites, and aphids. You can generally blast these pests off the leaves with a strong spray from your garden hose. Tent caterpillars will eat the leaves, so remove their silky nests as soon as you spot them and before much damage can be done. Japanese beetles can also feed on the tree’s foliage, and severe infestations can be controlled with spray insecticides.
A number of serious diseases can affect Japanese cherry, including leaf spots, dieback, leaf curl, powdery mildew, root rot, and fire blight. Consult your local Extension service for diagnosis and solution recommendations in your area.
Common Problems
Japanese flowering cherry trees are prone to a number of growing issues. Keeping your tree healthy is the best preventive measure, but the Japanese flowering cherry is a tree that sometimes requires a professional arborist to diagnose and treat problems.
Bark Splitting
A significant problem is bark-splitting, whereby large cracks emerge in the trunk. Such a crack can allow organisms to enter and subsequently cause decay. As a solution, trace with a knife just outside the split in the trunk and then remove the bark from inside the traced area. This will prevent the crack from expanding. If the tree is otherwise healthy, the area should callus over to prevent disease.
Gummy Residue Around Trunk
This is often an indication that the tree is fighting peach tree borers. You may also see wounds and cankers on the trunk of the tree when borers are attacking. Permethrin or other powerful insecticides will likely be necessary to control these pests, but take care not to spray during the bloom period, as this will kill pollinating bees.
Ragged Holes in Leaves
This is usually caused when Japanese beetles are feeding on the foliage. One effective method of control is to use pyrethrin-based insecticides. Horticultural soaps can also be effective, though application on a full-sized tree can be problematic.
How to Get to Bloom
Cherry blossom season lasts for about a month every spring and is always dependent on the weather. Early March to early April is generally a good rule of thumb when hoping to see blooms. However, if warm temperatures arrive sooner, they can encourage some cherry blossom trees to bloom as early as January and February. Most cherry blossom trees bloom for one to two weeks during the season. The further south you go, the earlier in the season the trees will bloom. When blooming, cherry blossoms make for easy and beautiful flower arrangements that can last quite a long time.
Trees that are planted in a location with favorable conditions will typically bloom well. Weather can sometimes be a factor. If a hard frost happens once the buds appear, it can cause the tree to lose its blooms for the season. However, the tree should return to blooming next year.
III. Uses and Benefits
The various non-fruiting cultivars of Japanese cherry trees are what are commonly grown for their splendid display of white or pink flowers in the spring. Their compact size and lush flowering make them extremely popular as specimen pieces in home and public gardens, and are absolutely essential in Japanese-style gardens. Typically, Japanese cherry trees are planted together to make an even more spectacular show, but it also works well with dandelions, chamomile, and lupines.
IV. Harvesting and Storage
The fruits of japanese cherry usually ripen in the early fall and can be picked for eating. If the fruit needs to be stored or transported a long distance, it is better to harvest the fruit before it softens, such as during the late summer or early fall. Note that fruit should be handled gently and, ideally, and the twig should remain on the fruit.
Find Where to Buy the Best Japanese Flowering Cherry (Prunus serrulata)
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