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How to Take Care of Japanese Juniper Bonsai (Our Guide Book)

A Japanese Juniper bonsai tree.

A miniature tree sitting in a pot by your garden adds aesthetic appeal to your terrace. Thus, you might love the idea of growing a pot of bonsai. But what is the best plant for it? Low-growing trees are ideally the best choice for bonsai gardening.

The Japanese Garden Juniper (Juniperus Procumbens) is a low-growing evergreen shrub or coniferous tree. The size of this plant generally ranges from 6 to 12 inches high and 4 to 6 feet wide. The juniper is a genus of over 50-70 species of the cypress family. The Japanese Juniper Bonsai is a specific variety that is native to the coastal regions in Japan. However, it can also be grown in other temperate parts of the world.

Bonsai gardening refers to the art of growing a specific tree in a container. However, it is more than just tree-growing! Having to grow a bonsai, which will resemble a miniature of a tree, is dependent on the care that you will provide.

The lifespan, growth, and longevity of your bonsai require patience and time. If you are a beginner in gardening or a beginner in growing a Japanese Juniper, this guide is perfect for you. Everything that you need to know to keep your Japanese Juniper Bonsai alive and growing is here!

Choosing the Right Pot or Container for Your Juniper Bonsai

A bonsai plant and various tools on a wooden table.

The pot is an essential part of the art of bonsai. It is not only the place where you will grow your plant, but it is also responsible for adding appeal to your garden. Since the root system of the bonsai plant needs to adapt to the smaller pot, you need to pick the right one from the start.

Consider the depth and measurement of the container. Other than the drainage hole, there should also be wiring holes. This will keep the plant fixed in the container.

The bonsai pot can be made from plastic, ceramic, and metal. The most common among them is ceramic. You can also make your own pot from scratch if you want! Just take note that your material should be something that does not hold or absorb water. The material that you use is crucial to the health and growth of your bonsai.

In choosing your pot, you have to consider its dimension, shape, and design.

Pot Dimension

The basic rule in getting the correct dimension is that the pot depth should be equal to the diameter of the trunk above the soil level. If it is an oval or rectangular pot, it should be 2/3 of the height of your tree. For round and square pots, the size should be 1/3 of the height of the tree.

Pot Shape

Before choosing the bonsai pot shape, you have to evaluate first if your tree is masculine or feminine. Sometimes it can be a combination of both, so you have to observe which one is dominant.

It is masculine if it has a thick trunk and mature or old bark. Strong and dense branches and other attributes can also suggest masculine traits. A feminine tree usually has a smooth trunk and bark, and it has a light canopy.

Rectangular pots are suitable for masculine trees. Oval pots fit the feminine one. Round pots are best for coniferous and deciduous feminine trees.

Pot Design

For a feminine design, the pot should be sleek with a soft line. For a masculine design, it should be deep, with a clean line and a lip on the rim. Also, you should remember that the color of the glaze for the pot should appear in the tree.

You can choose monochromatic colors or earth tones as it is safer. You may also choose contrasting colors as long as it creates harmony and balance.

Soil Suited for Your Juniper Bonsai

A gardener setting up the soil of the bonsai plant.

In finding the right soil for your Japanese Juniper Bonsai, you have to remember this rule of thumb: the higher the soil quality, the better the growth. You can mix and create your own soil, or you can purchase bonsai soil online.

Either way, you also have to remember the three important keys in choosing the best soil for nurturing the roots of your tree. Those are soil aeration, soil drainage, and soil water retention.

Soil Aeration

The root should receive the right amount of oxygen. So, you have to make sure that the soil is not very dense or compressed. It is better to have the soil slightly loose, so air can pass through, providing the proper root aeration.

Soil Drainage

If there is one thing that a bonsai cannot tolerate, it is “wet feet.” This refers to stagnant or excess moisture due to poor water drainage. You need to choose a soil that does not hold water for too long because it will prevent the root’s access to oxygen. Without access to oxygen, it will eventually weaken your bonsai tree.

Soil Water Retention

Japanese Juniper Bonsai cannot thrive in poor drainage as much as in drought. There should be a proper balance between your drainage and water retention. You have to make sure that the soil can provide the right amount of moisture. When you water your tree, you need some of that water to remain. So, you need to include materials that can effectively hold or retain just enough water for your roots.

The Akadama, which is a clay-like mineral, is used to achieve the right water retention.

Placement of Your Japanese Juniper Bonsai

A close look at a juniper bonsai tree.

Your Juniper Bonsai will never survive indoor cultivation. On some occasions, you can bring them indoors for decoration purposes. However, the bonsai should not remain inside the house for more than a few days.

They should stay most of the time outdoors and nearly year-round because they need to have access to a sufficient amount of sunlight. It is better if you place them in areas where the bright sun hits directly. You don’t have to worry about drought just as long as you are watering it regularly.

Watering

In watering your tree, there are several factors you have to consider. These factors include the climate, soil-mixture, and the size of the tree. Aside from that, you also need to observe your tree to determine how often you should water it.

There isn’t an exact time to water your tree. Water it when you feel like the soil is slightly dry – not when it is completely dry. Use your finger to feel and check the soil at around one centimeter deep. You can also use a moisture meter to gauge the water requirement of your tree. This way, you can prevent overwatering.

Apply water until it runs out of the drainage holes. Use a watering can with fine nozzle or hose that softer dispense water to prevent the soil from being washed away.

Fertilizing

Like most plants, your Japanese Juniper Bonsai needs sunlight, water, and soil to grow. However, to get that optimal growth, it also needs nutrients. These nutrients are given in the form of fertilizers. It will supply the vitamins and minerals to your tree so it can produce food for itself.

Your fertilizer should contain three important elements, which are nitrogen, phosphorus, and potassium. Most of the quality fertilizers are labeled with NPK vale and their corresponding ration in numbers. Each of the elements should be present in different amounts and ration depending on your types of tree or plant, type of soil, and time of the year.

Now the questions are when and how often should you apply fertilizer? If your bonsai tree is just starting to grow, apply fertilizer weekly. Use fertilizer in liquid form for easy absorption. They also tend to contain a higher nitrogen level for faster growth. But once its growth begins to slow down, you should reduce application to once every month. You can use pellets or balls then.

Pruning and Trimming

The various pruning and trimming tools of a bonsai.

Pruning is necessary to enhance the aesthetic appeal of the tree. By trimming the outer parts of the branches, you can stimulate the tree to redistribute its growth in the inner and lower parts. Japanese Juniper Bonsai trees usually have long shoots with a foliage pad that sometimes can grow dense. This will stick out at the sides beyond the silhouette of the tree. You can pinch or trim them at the base.

Make sure to use sharp scissors when doing so to prevent damage. The Juniper tree is stronger compared to other varieties. Therefore, it can withstand aggressive pruning. But do that only when the tree is more mature. Make sure that you are not cutting all the new growth, and be extra careful when removing the deadwood to avoid weakening the tree.

Wiring

Wiring refers to the process of shaping the tree. It is important because bonsai trees usually have a natural tendency to grow without any shape. But since you want it to be as vibrant and artistic as possible, you need to do the wiring.

A Japanese Juniper Bonsai is much stronger, but you can bend and twist them easily. It’s better to start wiring your bonsai when they’re still very young. You can protect the limbs or parts that are more delicate by wrapping them with raffia or tape. Thin out the foliage before you wire them. After wiring, fan out the foliage so the air can pass through, and the inner parts of the pads will not die.

Root Pruning and Repotting

The root system of plants tends to grow and become more extensive to supply the nutrients needed by your tree. So, when and how often should you repot your bonsai? It should be done once every two years.

The growth rate of trees is different. That’s why sometimes it can be less or more than two years. Hence, examining and observing the root system of your tree is important. Here are some steps and tips in repotting your Juniper Bonsai:

  • First, carefully remove the tree together with its soil from the pot
  • Cut one-third of the outermost and bottom part of the tree’s root mass. It is not good to remove or prune more than one-fourth of the roots
  • Put a mesh or screen over the drainage holes of the pot where you will transfer it. You can use either the same or a new pot
  • Then, put a sufficient amount of fresh soil that has good drainage on the pot. The soil you placed should elevate the tree in its previous height
  • Next, place the tree into the pot. The remaining vacant areas from root pruning should be filled with fresh soil again
  • After that, mist the plant with water and soak the entire pot in a tub of water, preferably with vitamin B-1. Use moss or ground cover to prevent soil erosion

Insect and Disease Control

A properly cared for bonsai tree.

Most of the time, if your Japanese Juniper Bonsai is well taken care of and is placed in a position with the right temperature and amount of light, you’ll have no problem. They will grow resistant against pests.

However, during the winter, you need to be extra careful. The position of your tree might not have enough access to sunlight. This will cause the foliage of the tree to get too dense, making it prone to pests.

Some of the most common pests that might infest your tree are spider mites, juniper scale, aphids, juniper needle miners, and webworms. You can use insecticide or miticide to remove them. Also, it is better if you can find an organic kind of insecticide or mixture.

When it comes to diseases, the most common is fungal rust disease, which can cause swelling. Although the susceptibility level of the juniper species to this disease usually differs, it is better to observe your tree from time to time. If the foliage of your tree is yellowish-green, it is more prone to the disease. Meanwhile, if it is darker or blue-green, it is more resistant.

Propagation

You can propagate the Japanese Juniper Bonsai through seeds or cutting. The best time to propagate bonsai through cutting is during the spring and summer. It is usually taken from the semi-hardwood part of your tree. It takes up to two years before you can start shaping, pruning, or wiring the plant.

Here are some other important tips you need to remember when cutting and planting a new juniper.

  • You should disinfect the bypass shears by soaking it in 1 part bleach and 9 part water solution
  • Choose a branch with fully matured needles and cut at the joint where the new and old branch and new growth joins
  • When placing the cutting in the pot with soil, bury the lower one-third or one-half of the stem
  • You should also cover the cutting with a plastic bag to protect it. Remove the plastic bag once it already produces roots and new growth
  • After a month, you can test if the roots are already growing by gently tugging it. Remember to mist the cuttings daily for constant moisture and to maintain its humidity. It is even better to plant multiple cutting for more chances of success. You have to be patient because it is not an easy task. Most certainly, it will take time before you savor the fruit – or in this case – the tree of your labor.
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