Buxus As Bonsai?

Boxwood make exceptionally long-lived bonsai. Many varieties of Buxus work very well and have been cultivated as bonsai for decades, but for the purposes of this article we shall address Korean Boxwood and Kingsville Boxwood-- two very popular types with which to work.

In my opinion, boxwoods are best used as informal uprights, or other more conventional styles. Although the tree could be used to emulate another species using the windswept style, it could be a bit of a 'stretch' design-wise.

I have several buxus in my collection, and can offer up these observations, both gleaned from reading material and my own conclusions.

Korean boxwood is an extremely slow growing evergreen shrub. It is almost impervious to pests and diseases. Of particular beauty is the pale buff bark, which takes on interesting rivulets and whorls as the tree matures.

This tree grows extremely slowly, as I stated before, but is quite amendable to hard pruning and will bud back, given adequate sunlight, feed, and water. I grow mine in full sun, in a fast draining soil of sifted Terragreen and rotted oak leaf (4 to 1, respectively.) The first tree (estimated age 40 years) was hard pruned almost down to the main trunk, with probably 10% of the original foliage mass remaining. All major pruning cuts were carefully reduced and sealed with Callousmate. One must balance energy carefully with box, because the tree will direct energy towards closing wounds rather than budding back or pushing top growth. Never hard prune near an area where you would like the tree to pop-- it will not happen until the wound is closed some years hence. Just leave stubs or stripped branches until the properly placed buds have formed and made several sets of leaves. Rub off unwanted buds. The inner branches must receive sunlight and ventilation if they are to bud. Often this means deep pruning to lighten and open up the dense 'clouds' of foliage which are common to the species. Bring sharp tools and big forearms to the job-- boxwood is an amazingly dense wood and difficult to hard prune. Incidentally, boxwood is sometimes seen as the material on woodworking (especially carving) tools; it's used for handles because of its density and toughness.

The other tree I have is a Kingsville Box, about 60 years old. It has a more compact growth habit, is even more slow growing, and is less winter hardy. This tree really likes to make dense foliage masses which screen out the inner branches and cause dieback. Be vigilant in keeping these inner areas well-lit and ventilated.

This tree can really utilize feed well, so I am pretty aggressive in fertilization. In Spring I lay down Osmocote, and supplement that with weekly watering with 20-20-20 and staggered with that, foliar feeding with fish emulsion. In Fall switch to a low to nil nitrogen feed. Wintering in Chicago, I chose a 4-25-35, which enabled it to lignify and harden off remarkably well. We had a brutal winter, but it came through fine. Korean Box is especially winter hardy to begin with. It will have no problems growing in any part of the Continental US.

My soil has a pH of about 6.50, which seems to suit them just fine. They appreciate a fairly neutral to alkaline soil.

Budding tips:

--Never hard prune near a desired budding point. Wounds must be reduced and carefully sealed. Stubs of unwanted branches can be left untreated, however, until the final pruning takes place. --Consider strategic placement of the tree with regard to the desired budding point(s) for maximum sun exposure. This can involve tilting the tree, rotating it during the day, etc. --Mist the wood frequently. Box will bud back even on very old wood. Remember to water well, as plump well-watered wood is more amendable to budding. --Keep in full sun. As long as current growth opened in full sun you will not experience leaf burn.

Lastly, the final chore for the development of this tree as bonsai would be reduction of the rootmass. Don't mess with the roots, other than the pruning of really poorly placed or angled roots and the careful arrangement during the initial repotting into freely draining soil. It doesn't 'harm' the tree, but we are concerned with maximum growth capabilities here.

If bonsai is the art of patience, then surely box is the ultimate in teaching one patience. However, the joys of seeing a bud pop exactly where you need it is really special. If I have prompted more questions please fire away!