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Japanese Tree Lilac: Plantation and Care

Gaurav Athavale Mar 21, 2020
One of the largest lilac species, the Japanese tree lilac is considered to be a small tree, and is used as an ornamental plant in parks and along sidewalks. Here's more information about this floral species, and instructions regarding plantation and tips for its maintenance.

Fast Fact

Though this lilac type is originally from Japan and few parts of China, its growth spread fast to other continents. Far from its native country, the Japanese lilac is now planted extensively in the USA.
A deciduous tree by habit, the Japanese lilac (Syringa reticulata) grows up to an average height of 14 meters, and has a trunk width of about 25 - 30 centimeters. The canopy spread varies between 3 to 6 meters.
The leaves are quite elongated and elliptical in shape, growing up to a length of 10 cm, while the flowers are white in color and have a size of about half a centimeter.
It has three varieties found in different regions of east Asia:
  • Syringa reticulata amurensis: Dominantly in northeastern parts of China and portions of southeast Russia.
  • Syringa reticulata pekinensis: Originated from central Chinese subcontinental regions.
  • Syringa reticulata reticulata: Mostly grows in Japan and surrounding areas, as well as in North America.
The particular species name (reticulata) is given due to the peculiar nature of net-like or reticular appearance of veins on the leaf underside. The white-colored blossoms are in clusters, and give a pleasant fragrance. This makes the lilac trees useful for backyards, gardens.
The flowers mainly bloom during the spring season. These lilacs are classified as being suitable under Plant Hardiness Zones of 3 to 7, as given by the U.S. Department of Agriculture. They can be maintained with minimum pruning or trimming, as their natural oval-shaped form is quite attractive. These trees have an annual growth rate of about 15 inches.

Steps to Follow While Planting the Japanese Tree Lilac

These lilacs grow properly if planted in areas that receive ample sunlight and less shade. They have thicker trunks than most of the other lilac species, and hence, are sturdy and tolerant against adverse weather conditions.
Choose the proper site for plantation, according to the hardiness zone range as mentioned here. Use a soil type that is slightly alkaline and well-drained. Keep in mind that this lilac will not grow properly in regions that have semi-arid to desert-like weather and appearance.
Dig a hole or a pit in the ground with a depth that is slightly more than the root length, and is at least 5 times wider, for effective growth. Break the soil clumps to make it fine and loose, so that the roots can penetrate it easily. Use soil amendments or compost/manure as required.
Preferably use saplings that are available in pots, rather than the ones that are sold off in plastic bags and containers. Carefully remove the sapling from the pot and place it in the pit in such a manner that the root ball should properly rest on the pit bed, which can lead to the growth of a straight and vertical stem.
Slowly fill in the loose soil around the plant, and pack the spot completely. Ensure that you have removed all the air pockets before leveling off the surface. You have to maintain a similar height that was present before the sapling's removal.
Remove all the diseased parts of the sapling, if any, before placing it in the pit, and add a layer of mulch for faster root growth. Make a trough-shaped circular structure around the plantation spot, which will hold the excess water that will seep down slowly till the roots.

Taking Care of the Japanese Tree Lilac

Before plantation, you can keep the sapling roots soaked in water for a couple of hours, as this will maintain the water circulation in the plant. Place them inside the pit immediately after the soaking is done.
Protect these trees from strong and intense winds, as the flowers and leaves are quite fragile and can break off easily. For this purpose, you can erect a fence or protective screen around the lilac, as well as above it.
Once damaged, the plant may not blossom in the next season, and it takes a year or two before it is capable of producing flowers. The reason being that, all its energy is used for repairing the damage, instead of flowering.
Apart from using manure and compost, addition of fertilizers is absolutely essential for this tree. Nutrients are provided to the plant through the medium of soil, which are then absorbed and synthesized.
You must regularly inspect and check on the plants for pest infestations. If infected, pesticides must be applied or sprayed immediately to prevent maximum damage, as the Japanese lilac is less resistant to pest attacks.
The major pests that affect this plant are leaf miner and lilac borer, while the main diseases that can occur are powdery mildew, verticillium wilt, bacterial crown gall, bacterial blight, and leaf blotch.

Diseases that Affect the Japanese Tree Lilac

Lilac borers make small holes or tunnels in the branches of the tree, if regular checks are not kept, including watering and providing fertilizers. This might lead to the weakening of the branches of the plant, and ultimately, they might drop off.
Similarly, leaf miners can cause extensive damage to the leaves, especially during summer time. If larvae mature into the pupae (caterpillars), then only a skeleton of the foliage remains; this might even cause the tree to die.
In case of leaf blotches, dark brown spots appear on the leaves that may be caused due to various fungi. The formation of a white-colored, fine, soft substance formed due to wet weather is called powdery mildew. When black spots appear in the form of stripes or lines on the lilac plant, it is affected by the disease called bacterial blight.
The disease that involves an abnormal growth of warts or lumps on the lilac stem is called bacterial crown gall, while wilting consists of weakening of the branches due to fungal infections, which might lead to them dropping off.
Apart from being used as ornamental trees in gardens and on sidewalks, Japanese lilacs are also planted along highways, lawns, public grounds, and as windbreaks in backyards. These trees are also popular among birds for making their nests. For growing this lilac variety, make sure that you have ample space to accommodate the wide expanse of its canopy.