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Tree of the Month - October 2004: Boxwood
Kingsville Boxwood – Buxus microphylla ‘Compacta’:

By Ken Schultz

For those of you that did not participate in the August ’04 Kingsville Boxwood workshop, I decided that I’d better write up the notes for a tree of the month article before I lost track of the material I used. I referenced several website articles and a few books from my personal library. As I noted these are a favorite of Linda and me, as we have five of them in our collection.

Kingsville Boxwood take their name from the nursery where it was discovered in Maryland in 1912. However it was not released to the public until 1937. At the suggestion of Dr. Wyman of Arnold Arboretum, Boston, Henry Hohman named this plant Buxus microphlylla var. compacta, but it was William Appleby of Baltimore that selected the seedlings in 1912. I found this interesting since most bonsai websites called it Japanese Kingsville Boxwood and it originated her in the USA. Seems that sellers think that we need to think that all our bonsai originate in Japan. In all fairness, boxwood were introduced to the United States in 1652 and were a favorite from Maryland to North Carolina. There are about 115 cultivars available today. Linda and I also have a “Korean” and a “Wintergreen” boxwood in our collection.

All my Kingsville Boxwood spend the winter outside, though I believe Jack Wickle had a mame’ Kingsville in his indoor collection. To that note, I did kill a mame’ Kingsville in my collection in 1995. It may have been the small pot, but I suspect that it was most likely that at that time I kept my trees on the west side of the house and the winter sun and wind probably killed it.

One of the articles I referenced from Persiano, from Shanti Bihthi nursery in CT provided three rules when working on styling a Kingsville Boxwood, these were:
1. Minimize foliage removal as Kingsville grow only ¼” to 1” per year.
2. Use copper wire – it will allow you to “feel” the movement of the branches and avoid breaking them.
3. Kingsville form naturally interesting shapes – use them before you cut.

Light - Boxwood will grow in either full sun or shade; indoors they need at least 800 Lux. I grow mine in semi-shade.

Temperature – protect from cold winds and winter sun. In the summer they need a breeze to prevent inside leaves from mildewing. They are hardy to zone 5. Winter injury can be caused by summer drought, prolonged rainy periods, and forced late growth; new growth may be burned back. Avoid sunny winter exposures.

Water – Box does not like wet soil so allow it to dry somewhat between watering. – but not DRY! Another source reports that they like water, and may even need water twice a day in hot weather – though mine never have.

Feeding – Use a liquid or organic fertilizer every two weeks. Much to my surprise – they do not recommend an acid fertilizer, in fact the claim is they like slightly alkaline soil, so an occasional dose of lime is recommended. Feeding May to October.
Repotting – every two years. Avoid really shallow pots. The claim is that they can be repotted in summer or autumn – I wouldn’t – these recommendations are for the south and the west!

Propagation – from cuttings. The Commercial Boxwood Production article says that these cuttings are best taken in late summer to fall. (remember this is for nurserymen in North Carolina and Oregon). The cuttings are placed in equal parts- sharp builder’s sand peat and perlite in a shaded area. Because of the lateness of taking these cuttings watering even in winter is recommended as is some bottom heating. In another place it says to use 8 parts pine bark, 1 part builders sand and a little dolomitic limestone.

Pests – red spider mites, fungus and rust may be encountered. Watch for curled or pock marked leaves. Root rot is also noted as a problem, usually one branch at a time dies. This can be associated with nematoads. Use “Subdue” Leaf miners can also cause blisters on the leaves, spider mites cause scratch like marks. Over wintering eggs are laid in September and October. Violets, chickweed and mustard may serve as host plants – so weed them out.

In closing I have seen small accent sized Kingsville for as little as $2 and a specimen plant for $300, so if you know someone who wants to take one out of their landscape – give me a call!


Tree of the Month - May 2003: Boxwood

Botanical name: Buxus sp.

In spite of the name I can find no records of boxwood being used to make boxes, However, it was used as an extremely durable fine grained wood for printing and precision instruments.. The end grain would take and hold fine carvings for specialty printing needs without the need to cast or engrave special metal type. Boxes are densely branched shrubs native to Europe and Asia. Caution: box leaves are poisonous, and eating even a few can kill a small pet.

All the varieties of boxwood will make good bonsai. For those of us in hard winter areas, we need to select the hardier varieties or plan on having some winter protection plan for the southern varieties. For Mame or Shohin bonsai, Buxus microphylla x. compacta var. kingsville is a proven favorite. It can have beautiful nebari, and the tiny leaf size adds to the illusion of age and majestic proportions in a small tree. However, in recent years new versions of non-“kingsville” and its predecessors - B. microphylla and B. compacta - produce wonderful small trees. For larger bonsai, the Korean, Japanese, and older forms of English boxwood have proven to produce fine specimens. Many of the larger forms are available in your local garden center. The Korean box (Buxus microphylla var. koreana) is the hardiest species of all the boxwood and its' popular cultivar 'Winter Green' is especially tough and attractive. This has small, dense, light green foliage. Winter green box, retains its good green leaf color during the dormant season, unlike the ordinary species which turns light brown.

Another recently discovered cultivar, Chicagoland Greenª boxwood (Buxus x ‘Glencoe’), has proved to be an excellent performer as far north as Minneapolis. This cultivar sports medium green foliage year-round and is a rather quick grower (everything is relative). Twelve year old plants at the Chicago Botanic Garden, where the plant was discovered, measure 3’ tall and 5’ wide.

Boxwood can be wired when branches are young and seem to thrive as pot plants. This would help explain their common use as topiary subjects as well as bonsai. Boxwood tends to be generally slow growing and the hard wood resists wiring after it has hardened. Several years may be needed to move a branch.

Repot boxwood every two years. Spring is the best time, but it can be repotted in summer and fall if needed. But, avoid repotting during very hot weather or during a growth spurt. Use basic bonsai soil. Boxwood dislikes acid soil, and the use of limestone in the soil mix or adding an occasional dose of lime to the soil is recommended. Soil must be well drained. Their root system tends to have a stringy quality that tolerates root pruning well. It is not the matted fibrous roots of potted azaleas or junipers, but has similar characteristics if it becomes root bound. I have had good luck just cutting out wedges and the periphery of the stringy roots when repotting Wiring the tree into the pot is very important for re-establishment of roots in the pot. This allows them to be grown in a variety of individual styles as well as in miniature landscapes.

Pests and diseases: Nematodes, mites and leaf miners, scale insects, blackfly, greenfly, and red spider mites. Although box is very disease resistant, honey fungus and rust are sometimes encountered.

Boxwood are forgiving in their growing location as they have been adapted to many locations over the years. Originating as an under story plant they tolerate medium shade, filtered sun, or full sun for the varieties adapted for hedging. If you have a specimen that is getting leggy then try putting it in the ground in full sun for a year or two. It will back bud and fill in allowing you to chase the foliage pads back to where they should be for your design.

Watering: Boxwood likes water, particularly when in a pot. It is important to keep the shallow root system cool and moist. Small boxwood bonsai should be kept damp and watered twice daily in hot weather. However, do not allow the soil to become saturated or the pot to stand in water.

Woody cuttings can be taken any time during the growing season. My experience with boxwood cuttings is they are very slow to root and will continue to be green and apparently healthy several months after cuttings are struck, even if there has been no visible root growth. I have learned not to disturb boxwood cuttings until I can see new growth on the tips of the branchlets. I have read a couple of places hat fall cutting can yield good results, but this has not been my experience. Those authors my live in the south and have very mild winters to contend with.

Boxwood likes a balanced fertilizer from the time it buds out to late fall. In Columbus this would be late April to October.

Over-wintering: Shelter the hardy boxwoods from winter sun. It doesn’t have to be absolute, a partly sunny or shady location, possibly in the under story of a large tree or under a bench, or on the east or north side of a building or fence

References: by Sabrina Caine and Thomas L. Zane
Boxwood in the North? by Jeff Epping, in Articles/boxwood.htm


Species Guide: Boxwood
By Keith Scot

Species: Common name: Boxwood
Botanical name: Buxus
Japanese name: Hime-tsuge

Varieties used as bonsai: For smaller bonsai the Buxus microphylla compacta "kingsville" has no real peer; however, in recent years reversions of kingsville have flooded the bonsai market. For larger bonsai, the Korean, Japanese, and older forms of English boxwood have proven to produce fine specimens.

Advantages: "Kingsville" as well as its predecessors, microphylla and compacta produce superior small trees. Their ruddy bark and good buttress formation set them apart. But the most engaging factor is their small leaves. They can be wired when branches are young and seem to thrive as pot plants. Their abundant root system allows them to be grown in a variety of individual styles as well as in miniature landscapes.

Disadvantages: Slow to produce vigorous growth when newly propagated. Also, they tend to be generally slow growing except in the tree forms. While hardy, many of the southern boxwoods do not tolerate Pittsburgh winters. Since they are broad-leave evergreens that will profit from winter protection, particularly from sun.

Suitability as bonsai (1 is least suitable 10 is most suitable): 9/10

Growing location: Filtered sun

Watering: Boxwood likes water, particularly when in a pot. Small boxwood bonsai should be kept damp and watered twice daily in hot weather.

Propagation: Woody cuttings can be taken any time during the growing season.

Fertilizing: Balanced fertilizer May to October.

Over-wintering: Shelter the boxwood from winter sun.

Styling: Informal upright and in tray landscapes.