Buxus bonsai, also known as boxwood, are evergreen trees that are used as bonsai that are part of the Buxus genus. This genus contains over 70 tree species. These species of trees can be found in Asia, Europe, Africa, and Central America.
Of all these species, however, the Chinese boxwood (Buxus harlandii), Japanese boxwood (Buxus microphylla), and the European common boxwood (Buxus sempervirens) are most often used as bonsai. They are extremely popular bonsai due to their hardiness and ease of styling which makes them easy to find in almost any nursery.
Boxwood bonsai are often styled with twisted trunks due to their natural inclination towards this style. Boxwood trees found in the wild also often have twisted trunks and branches. These trees are also commonly used in garden landscaping due to their ease of being shaped into stunning shapes and are sometimes used as hedges.
Boxwood trees naturally have very tiny leaves. This makes them look more balanced as a bonsai tree. The leaves also grow in a very compact fashion which is often soughed after in bonsai trees. Broxwood is very popular, especially in England due to this compact leave structure making it easy to style.
These trees are very hardy, capable of growing on barren soil in full sun or in shade. They also tolerate trimming very well making them easy to style during any time of the year. Buxus bonsai is also one of the few that buds readily from old wood which also contributes to their popularity as potted trees.
Boxwood bonsai need winter to become dormant but of all the species available as bonsai, only common boxwood tolerates very cold weather. Despite this tree being frost-resistant in the wild, it should be protected against frost when planted as a bonsai.
It is a very popular outdoor bonsai tree due to its hardiness and needs for a dormant period. This makes boxwood ideal for patios with no cold drafts that are protected from frost.
Care Guidelines For Buxus (Boxwood) Bonsai
Buxus bonsai are quite hardy and easy to care for. Here is a quick Buxus guide to get you started.
Ideal Placement
Buxus bonsai do best when placed outside in full sun or semi-shade. If your tree has full sun, make sure to protect it against the harshest rays of the sun during midday in summer. Too much sun, especially in hot climates, can cause leave burn on boxwood bonsai.
Boxwood bonsai needs to be allowed to become dormant in the winter months. To achieve this, you can place your bonsai outdoors in an area protected from frost and cold drafts. An outdoor shed works great for this purpose as long as there’s still enough light.
Chinese boxwood is more sensitive to cold, but also still requires a dormant period. To protect your tree against very cold temperatures you can bring it indoors and place it in a room with a temperature around 50° Fahrenheit (10°C). Make sure your plant still gets some light, but it doesn’t have to be direct sunlight.
If you don’t have an indoor area that is cold enough, you can place your tree in the garden shed.
Water Requirements
Buxus bonsai are quite thirsty little trees during the growing season. Fortunately, they can also withstand short periods of dryness if you forget to water your plant. This makes them ideal for those of us without a green thumb.
Buxus bonsai placed in full sun locations will also dry out faster than those placed in semi-shade. For this reason, you will need to check your bonsai daily and water when necessary. Make sure you don’t overwater your little tree. Boxwood bonsai doesn’t tolerate excess moisture for long periods of time.
To check the moisture content of your soil, simply stick your finger around 1 inch (2.5cm) into the soil. If the soil feels moist, you don’t have to water just yet. Check again later in the day. If the soil feels dry, however, you can go ahead and thoroughly water your bonsai.
Boxwood bonsai isn’t that picky when it comes to water pH either. You can water your tree with normal, good-quality tap water in most cases. If you want to keep to the ideal pH, try going for water with a pH of around 7 to 8.
The best way to water your bonsai is to submerge it in water to the rim of the pot. Leave it submerged for a few minutes before allowing it to drain and moving it back to its original location.
Soil And Fertilizing
Bonsai trees are usually planted in very shallow pots. The Buxus bonsai is no exception to this rule. Because of how little soil bonsai have to grow with, the soil will get depleted of nutrients quite quickly. Watering your bonsai also contributes to nutrient loss as the water leaches it away.
To keep your tree healthy and counter nutrient loss, you will need to fertilize your plant frequently. Experts advise fertilizing your bonsai with a solid fertilizer once a month during the growing season. If you don’t want to use solid fertilizer, you can also consider liquid fertilizer/
Liquid fertilizer needs to be used once a week. Make sure to not place your liquid fertilizer on dry soil. It will damage your tree’s roots. Always water your bonsai before fertilizing.
Most Buxus bonsai don’t need fertilizing during the three months of winter if you’re using solid fertilizer. If you’re using liquid fertilizer, you can reduce the frequency to once a month. Chinese boxwood, however, is never completely dormant and will need more fertilizing during winter.
Pruning Times
Common boxwood tolerates hard pruning and extensive back cutting very well. You will need to prune back any unwanted shoots to one or two pairs of leaves left to keep your trees from.
In some cases, the canopy of your little tree can become very dense. If this happens you will have to reduce the number of leaves to let light through to the inner twigs to prevent them from dying. Trimming away the leaves will also encourage back budding.
It is also a great idea to prune inner branches regularly. Doing so will encourage back budding and retention of leaves. Thinning of the leaves will also trigger new shoots. These shoots can then be trained into the desired positions.
Repotting Times
Buxus Bonzai needs to be repotted every two to five years depending on the age of your little tree. The ideal time to repot boxwood bonsai is in spring, just before the growing season starts. These bonzai tend to handle root pruning very well which makes it easy to maintain the roots of the tree.
You can trim the surface roots back by around 10 % to encourage new root growth. If you notice your tree’s growth is stunted, it might be time for another repotting since Buxus tend to stop growing when it runs out of pot space to grow new roots.
Make sure to not repot your tree sooner than two years after the last repotting, however. Doing so will encourage vigorous growth that is undesirable in bonsai.
When mixing your new soil try to get the pH as close to 7 or 8 as possible. You can do this by mixing pumice or lime rock gravel into your normal soil mix.
Propagation Management
The best way to propagate Buxus bonsai is by taking cuttings or doing air layering. For the best results, try these techniques in spring. You can also grow boxwood bonsai from seeds, but this method of propagation isn’t preferred.
It takes a very long time, several years, to get a boxwood grown from seed to reach a size that you can start to prune and shape your tree into the desired form. It will take several more years for the shaping to show any remarkable results and thickening the trunk can also take a while.
Potential Pests And Diseases
Boxwood bonsai are known to be quite hardy, but they are still susceptible to a range of pests and diseases. The most common problem in these trees is fortunately very preventable. Boxwood bonsai are quite sensitive to being overwatered and may develop root rot quite quickly as a result. Signs of overwatering include mold, the yellowing of leaves, and of course smelly roots in soggy soil.
To prevent this problem, simply check your soil every time before you water your plant. Do the finger test as mentioned above to decide if watering is necessary. Keep in mind that boxwood bonsai need to be allowed to dry out between waterings to stay healthy.
Another common problem to look out for is pesky insects. Pests like nematodes, scale, boxwood mites, boxwood leaf miner, boxwood psyllid, or boxwood moth caterpillars are commonly found on weakened or even healthy Buxus bonsai. The boxwood moth has become quite a severe problem in recent years, especially in Europe. The caterpillars from this moth can turn your bonsai into a skeleton version of your original tree quite quickly doing irreparable damage.
To control and prevent pests, you will need to inspect your tree regularly. Make sure your bonsai is as healthy as possible by following a proper watering and fertilizing schedule and make sure it gets enough sunlight. If you notice any pests, use a pest-specific pesticide bought from the store or make your own organic pesticide at home by using ingredients like vinegar.
Make sure the soil of your tree is wet before you apply any pesticides. You will also need to adjust the dosage to not harm your small tree.
Other afflictions you need to look out for are fungal diseases. Boxwood is quite prone to developing box blight or phytophthora root rot for instance.
Wiring Your Bonsai
Boxwood is one of the few bonsai that handle extensive deadwood sculpting very well. Keep in mind that boxwood isn’t the fastest-growing bonsai so don’t trim away too much growth during training.
If you’re planning on doing some wiring to help with training, take extra care not to damage the bark. Damage to this tree’s bark takes a very long time to heal due to its slow growth. Wires can, however, be left on for as long as necessary as long as you take time to adjust them to prevent any damage.
When the time comes to remove the wire completely, make sure to cut it instead of trying to unwind it in one piece. Boxwood branches are quite fragile and might be broken in your attempts to unwind the wire.
It is also best to use the softest wire possible that will still do the desired job. This way you can get the training done with minimal risk to the bark. Fortunately, wiring can be done at any time of the year as long as your tree is strong enough to not sustain major damage.
For the best result, style, and wire your tree during the growing season. It is best to train new branches as soon as they are thick enough not to break while being bent but still supple enough to take on new positions.
Q. When Should I Repot Buxus Bonsai?
A. Buxus bonsai needs to be repotted every two to three years to keep your tree healthy. It is best to do repotting in midsummer to avoid stressing your tree. When repotting use a basic soil mix with a bit of pumice or lime rock mixed in to encourage vigor. Make sure your soil mix drains well while still retaining some moisture.
Q. Are Buxus Bonsai Poisonous?
A. All species of Buxus are poisonous when ingested. Make sure to place your bonsai out of reach of curious children and pets.