Chinese box ‘Wintergreen’ (Buxus sinica var. insularis ‘Wintergreen’)

Chinese box ‘Wintergreen’ is a compact evergreen shrub known for its lush, small, dark green leaves that hold their color even through winter. The foliage adorns a densely branching structure that can mature into a formal hedge or a sculpted garden feature. This variety thrives in well-drained soils and partial to full sun, showing resistance to boxwood blight, making it a hardy and attractive choice for year-round interest.

I. Appearance and Characteristics

The Korean boxwood is an often maligned, but underestimated, evergreen shrub for the landscape. Some of you may recognize the older name: B. microphylla var. koreana for this plant. This broadleaf evergreen member of the Buxaceae can grow up to 4 ft. tall with a spread of 4-5 ft. Growing best in full sun with moderate soil moisture, plants can tolerate part shade if not over-watered.

Foliage of Buxus sinica var. insularis, as a species, will turn brownish yellow in Midwestern winters. However, leaves of ‘Wintergreen’ are much less likely to display this color change and will remain green to green-yellow throughout the winter. ‘Wintergreen’ also shows improved resistance to the three primary insect pests of boxwood: boxwood leaf miner, boxwood mite, and psyllids.

All parts of chinese box ‘Wintergreen’ are extremely toxic to cats, and suspected ingestion warrants a visit to the vet. The symptoms of Buxus sinica var. insularis ‘Wintergreen’ poisoning may include vomiting, diarrhea, lethargy, and convulsions, with respiratory arrest and paralysis in extreme cases. Fortunately, the plant itself is very bitter, which usually prevents cats from eating it in larger amounts.

II. How to Grow and Care

Sunlight

Chinese box ‘Wintergreen’ likes sufficient sunlight but can tolerate partial shade too. Thus, it can grow well both indoors and outdoors. You can plant it almost anywhere, except for spots that are completely in the shade all day long. If it doesn’t receive enough sunlight, the leaves may turn yellow. There are other species in the Buxus genus that prefer low light environments, which are best grown somewhere with partial shade that avoids direct blazing sunlight in the summer.

Temperature

Chinese box ‘Wintergreen’ is mainly distributed in temperate regions and prefers a warmer climate. However, it is cold-resistant to a degree, too. Chinese box ‘Wintergreen’ can grow at temperatures in the range of -23 to 35 ℃ but will become dormant and stop growing if the temperature goes outside of this range. If the temperature stays around 16 to 27 ℃, it will be vigorous and grow rapidly. It prefers moist soil but is also tolerant of dry conditions. However, it is not tolerant of waterlogging.

Watering

Chinese box ‘Wintergreen’ likes moist soil but is not tolerant of waterlogging. If its leaves turn yellow, you are advised to reduce the frequency of watering. During spring and summer, it grows exuberantly and requires timely watering. Water thoroughly each time.

If the weather gets too hot, water it twice a day, once in the early morning and once in the evening. In the fall, its growth will slow and the frequency of watering can be reduced. If it is grown in a pot, continue to water regularly, as the soil in a pot will dry out more quickly.

Soil

Chinese box ‘Wintergreen’ doesn’t require a specific soil type but does like the soil to be moist and fertile. It can even grow in dry and barren conditions. However, due to its intolerance of waterlogging, it is recommended to plant it in sandy soil with good drainage, rather than in clay soil.

Fertilizing

Chinese box ‘Wintergreen’ produces small flowers, so it does not require much fertilizer. It should be given fertilizer two or three times during its vigorous growth stage, at the same time as you water it. Use fully decomposed organic fertilizer, but don’t add too much.

Planting Instructions

It is recommended to plant chinese box ‘Wintergreen’ in the spring, so it has an opportunity to grow strong enough before winter comes. Also, the weather in spring is mild and warm, unlike in the summer when heat and drought could hinder its ability to adapt to a new environment. If you plant it in the garden, you should choose somewhere that receives 5-6 hours of sunlight each day, and soil that has good drainage. Water it immediately after planting. If the weather is very dry, you should continue to water it each day for three consecutive days.

If you plant chinese box ‘Wintergreen’ in a pot, it is best to choose a pot big enough to allow ample space for its roots to grow. Clay pots are the best option as they have excellent ventilation and help the roots to breathe. When planting, you can trim off any old or dead roots; this will stimulate the growth of new roots. In general, chinese box ‘Wintergreen’ should be re-potted every 2-3 years.

It is advisable to do this before the budding of new leaves as their growth requires plentiful nutrition. You can also trim the roots when re-potting, and replace the soil.

Pruning

Chinese box ‘Wintergreen’ is very tolerant of pruning and tends to rapidly grow new twigs after it has been clipped. You can trim it into different looks depending on your needs. It is best to prune in the summer and winter. In summer, the plant is lush but the ventilation among the branches and leaves is not great, making it vulnerable to pests and diseases. In winter, it grows slowly and can maintain a certain ornamental look for longer. You can trim off any leaves that are old, dead, or have changed color, to make the plant look more presentable.

Transplanting

Chinese box ‘Wintergreen’ thrives best when transplanted in early to mid-spring due to cooler temperatures and ample moisture. Choose a well-drained, partially shaded location to ensure optimal growth. Provide adequate watering post-transplant for successful establishment.

Pests and Diseases

Keep an eye out for box sucker, mussel scale, box red spider mite, leaf spot and box blight.

III. Uses and Benefits

Chinese box ‘Wintergreen’ is very versatile, this plant is perfect for beds, borders, containers, formal gardens, Mediterranean gardens.