Historical Roots of Buxus microphylla
The Kingsville Boxwood takes its name from the nursery where it was discovered in Maryland back in 1912. But it was only released to the public in 1937. It is also quite interesting that many bonsai websites call it the Japanese Kingsville Boxwood, but it originated in the U.S. This may be because the initial sellers feel that people need to think that all bonsais are hailed from the land of the rising sun — Japan. Even before 1912, though, the boxwood species can already be traced as far back as 1652 and were a favorite in Maryland and North Carolina. Today, there are about 115 available cultivars.
Scientific Roots of B. microphylla
The Japanese Kingsville Boxwood belongs to the genus Buxus of the Buxacae family. This family varies widely as it also includes common boxwoods and Pachysandra of ground cover fame. Boxwoods are slow-growing evergreen trees and shrubs with undivided leathery and short-stalked leaves. They have petal-less flowers and fruits that explode on contact when ripe. The hardiest of boxwoods are the B. microphylla, with their wood durable and fine-grained.
If you notice, the leaves turn from dark green during the growing season to lime green or even yellowish during the colder weather. The color usually returns to green in the spring, and then you’ll need to remove the old and yellow leaves.
The Japanese Kingsville Boxwood is unique among other boxwoods because of its scentless evergreen leaves that are not even one inch long in size. Moreover, the Kingsville Dwarf is the most sought-after among the Buxus family. This is because it has all the good bonsai plant features: rough bark, tiny leathery leaves, and dense growth habits. The branches also grow horizontally, giving it a look that resembles a miniature version of an old shade tree. But be sure to keep the leaves from your pets’ reach as they are poisonous enough to kill them.
Different Buxus Species
The Buxus is a genus that has 70 species of shrubs and trees. Heights for these species vary from six up to 30 feet tall. They can be found worldwide, including in western and southern Europe, Asia, the Caribbean, and many more. While the European and Asian species are winter hardy, most are tropical and not usually used as bonsais. Out of the 70 species, there are four that are commonly used for bonsai:
- Japanese Boxwood (Buxus microphylla)
- Common Boxwood or European Boxwood (Buxus sempirvirens)
- Korean Boxwood (Buxus sinica)
- Chinese Boxwood (Buxus harlandii)
The Kingsville is a mutation of Buxus microphylla. You can get one from a hedge that is being removed. This way, you can guarantee age, thick trunks, and dense, compact growth that is already established. But you can also opt for buying a five-gallon specimen from nurseries. Once you have a sapling, grow it for a few years to make a bonsai, or you can use it as part of a group. For the best results, though, put your seedling in the ground and come back after 10 to 20 years. But say you are collecting for a landscape or hedging material, collect in mid-spring because the tree will have emerged from dormancy, and you will be able to get many roots.
On another note, boxwoods are semi-succulent, with their roots tending to be fibrous and fleshy. But while these traits may make potting easy, some boxwoods react oddly when their roots are disturbed. We say oddly as in their leaves may turn some shade of orange and pink and then refuse to grow for weeks and months after root pruning.
How to Care for Your Japanese Kingsville Boxwood Bonsai
It is easy to care for a B. microphylla. You can even shape it into a round ball through proper trimming. It may be easy, but only with proper care shall your bonsai truly remain beautiful, healthy, and miniature for the years to come.
And if you are wondering if this variety can grow indoors…it can and can also thrive as a bonsai specimen. Indoor boxwood bonsais just need enough water because they dry out quickly.
Position and Lighting
Generally, boxwoods are outdoor plants. Still, you can get away with growing one in a conservatory or sunroom.
During spring and summer, you can keep your Kingsville bonsai outdoors as long as it is in a semi-shaded area. The tree typically grows in nature under a canopy where it does not receive direct sunlight. Such placement actually keeps the Japanese Kingsville Boxwood happy.
Furthermore, your tree can handle some morning sun but will need shade when the afternoon hits. Be careful when exposing your bonsai to the afternoon sun if you reside in hotter climates to avoid baking them.
During winters, on the other hand, your tree will go semi-dormant. Make sure to move your tree to a window near a cold area with indirect sunlight. Say around 50 degrees Fahrenheit. Some bonsai enthusiasts have reported luck keeping their Kingsville Boxwood bonsai outside despite the cold temperatures. Such situations may be due to the trees’ aversion to lack of humidity or the warm temperatures inside if it is a long winter.
Temperature and Humidity Requirements
One of the best things about the Japanese Kingsville Boxwood bonsai is that it can handle a wide range of temperatures. And based on what you read above, it can even withstand cold temperatures. Remember to keep them in temperatures above freezing during winters but prevent them from becoming too warm because it will prevent your tree from going dormant.
Now, you will have to adjust the humidity if you want to bring your bonsai inside during winter. The environment indoors is much less humid because of cooling and heating systems. Simply mist your Kingsville Boxwood once a week and consider using a humidity tray underneath it for the extra humidity.
Looking for a humidity tray? Check out our shop for one!
Your bonsai is sure to grow best when planted in sandy, loamy soil. This type of soil is excellent in retaining enough water for it to be moist, but not so much that it becomes soggy.
Another reminder would be to forego using regular potting soil with your Japanese Kingsville. Common potting soil mixes do not have the appropriate amount of drainage, and since bonsais are placed in small pots, your tree will stay in one pot for several years. Consequently, you can either purchase a specifically designed soil for your bonsai or make your own mix.
There are multiple factors, like location and weather, that influence the frequency of watering your bonsai. However, the rule of thumb is to water them enough to keep the soil moist but not too soggy. If the soil dries out, that’s okay. Just make sure not to wait long before watering it again.
You can also go a bit longer between waterings (once a week) during the fall and winter seasons. During summers, water every one to two days, then adjust accordingly when spring comes. The best way to know when to water is by checking the soil. Just stick your finger about one inch into the soil, and if it’s dry, then it’s about time you water.
To ensure that your Japanese Kingsville Boxwood is healthy and happy with you, it will need fertilizer from time to time. Similarly with other bonsai plants, your boxwood can’t get all the necessary nutrients from just the small pot, unlike when it is planted in the ground.
Fertilizing would then have to be done once a month, especially during growing seasons (spring and summer), using a general all-purpose liquid fertilizer.
The Japanese Kingsville Boxwood’s versatility is outstanding when it comes to styling. You can choose almost any style aside from cascade. If you’re still only beginning, you can get the best result when choosing an informal upright style. But the most popular options are the twin upright, informal upright, and groups.
You can use mature cuttings that are dipped in rooting hormones that work great if done in a cool greenhouse. Make sure to place the cuttings in equal parts of peat, sharp builder’s sand, and perlite. It would also be best for you to water them in winter or add some bottom heating and even consider air layering for the large specimens.
Pruning and wiring
During fall and early spring, severe cuts can be made. It is also in springtime that pruning is optimal. And with the boxwood species’ slow growth rate, it is relatively easy to keep your bonsai’s shape.
When it comes to wiring, you can do it year-round as long as you are careful with the brittle branches. You can also control the shape by thinning and pinching off the unwanted growth.
This one is usually only needed every other year during spring. But when it comes to group plantings, every four or five years will suffice. You can also halve the roots in volume because the root system tends to have a stringy quality that can tolerate root pruning exceptionally well.
Pests and diseases
You may encounter fungus, red spider mites, and even rust with a Japanese Kingsville Boxwood bonsai. Also, watch out for curled or pock-marked leaves. Another problem you may have to face is root rot, with one branch dying at a time, mainly caused by nematodes. And if you find blisters or scratch marks, those are caused by leaf miners and spider mites.
Don’t know where to buy a Kingsville Boxwood? Luckily for you we sell quite a bunch! Just visit our shop to find one (or seven!)