By Reiner Goebel
Eastern White Cedar
(The name "cedar" is a misnomer-true cedars are native to Africa and Asia) is an evergreen native to the northeastern part of North America roughly bounded in the north by a line drawn from the southern tip of Hudson Bay west to the Ontario/Manitoba border and east to Nova Scotia. In the south, it occurs along the southern shores of the Great Lakes and most of the New England states. The leaves are yellowish-green and scale-like. The fibrous bark is reddish brown and peels off in narrow strips. Both wood and foliage are highly aromatic. The wood of eastern white cedar is long lasting, making the species an ideal subject for driftwood style bonsai.
Figure 1: Bottom view of eastern white cedar
(Thuja occidentalis) rootball
When growing in the open, cedars are straight-trunked with a slightly conical, columnar crown that extends to the ground. The foliage is dense, and the tree has an almost pruned appearance. The root system is shallow and wide-spreading, making the trees adapt easily to life in a bonsai pot (figures 1 and 2).
Figure 2: White cedar rootball side view
In areas where they are subjected to abuse by wildlife and the elements, cedars attain the trunk shapes that make them ideal bonsai subjects. Because of poor soil conditions and periods of extended drought during the growing seasons, cedars growing under those conditions are naturally dwarfed, and can frequently be found with shari and jin in place, although requiring some refinement. Cedars are suitable for all bonsai styles with the possible exception of literati. It is their rugged appearance and usually well tapered trunk that make them unsuitable for this style.
If cedars have a drawback, it must be their foliage. It is similar to the foliage of Hinoki cypress but not as tight. On the other hand, it is not as curly. Fronds will grow every which way, and the view of regular cedar foliage can be daunting for the cedar novice (figure 3). However, with judicious pruning and pinching (figures 4 and 5), it can be forced to behave and form foliage pads not unlike those of junipers.
Figure 3: Typical folige on unpruned white cedar
Figure 4: Typical folige frond before pinching
Figure 5: Cedar frond after pinching
Cedars grow throughout the growing season without a period of rest if conditions are appropriate, which they should be if they are being grown as bonsai. They therefore need to be pruned and pinched frequently. If you time your pruning sessions to coincide with the appearance of Haley's Comet, your cedars will not look good. Each of my trees is subjected to at least two scissors pruning sessions per growing season in addition to being pinched whenever something sticks up, down, or out. Unless this pruning is carried out religiously, cedars will develop elongated shoots with long internodes.
While I have seen cedars bud back on 3OO-year-old trunks in the bush, I have never had that happen on the trees I grow as bonsai. There must be special ingredients in the air "up north." Anyway, they do bud back on younger twigs, and also on areas of the trunk where branches are already growing (figure 6)-a somewhat redundant feature.
Figure 6: Back-budding on older wood
As with other trees, cedars shed old foliage in fall. Sometime in September, part of the foliage- usually in the interior of the tree- will turn rusty brown and slowly fall off (figures 7 and 8). If you're not sure whether your tree is shedding or dying, pulling at the brown foliage is a reliable test, because the foliage about to be shed comes off easily, while the foliage about to die requires a lot of force to remove. From my own observation, I believe that this natural shedding can be reduced by timing one of the heavy pruning sessions to occur around the middle of August.
Cedars like lots of fertilizer, and I feed mine weekly with a full strength 30-10-10 chemical fertilizer beginning about the end of May and ending the middle of August, with another couple of applications in late September and early October. I alternate between different products, including Miracid. Such fertilizing gives the trees dark green foliage and lots of growth, which, of course, is mostly pruned off, but does contribute to the denseness of the foliage pads. I start with the fertilizing regimen in the year following collecting.
Healthy white cedar foliage in early spring
Naturally occurring deadwood
on white cedar
Close view of white cedar deadwood
Cedars are relatively free of pests. The only ones I have ever encountered are scale and leaf miner, both controlled by spraying with a svstemic insecticide. A cedar suffering from a leaf miner infestation is not a pretty sight (figures 9, 10, and 11), and ever since ilmost my whole collection of cedars was attacked by these insects in 1994, I give them two precautionary applications of a systemic insecticide-one in early May and another about two or three weeks later.
Figure 9: Leaf miner damage
Figure 10: Severe leaf miner infestation Figure 11: Another severe leaf miner infestation
I spent much of the spring of 1995 plucking all the dead foliage off the trees, but I am happy to report that they all survived.
As you would expect from a tree that is native to this region of the American continent, cedars are very winter hardy. If you have marveled at the pictures of growers in some parts of Japan leaving bonsai on their benches all year round, marvel no more, because that is what I have been doing with some of my cedars. Why not all? Well, better safe than sorry, so while it is true that I have left cedars sitting on the bench all winter long, I do use some judgment, mainly relating to the size of the root ball. But putting the trees on the ground in a shady spot is quite adequate to ensure their survival in the Toronto area.
Cedar foliage, like that of some junipers, changes colour in winter, becoming grayish-green with maroon undertones. This can be startling to those not familiar with the tree's habits, but checking the underside of the foliage should still reveal a healthy light green shade and signal that all is well. The winter colour disappears within a few days in spring.
Cedars are very particular when it comes to wiring the young fronds. There is no problem wiring branches, other than that old ones are very stiff and somewhat brittle, but because they dislike having foliage wired into a different position, I do this type of shaping exclusively by pruning and regrowing.
As I hope the accompanying pictures show, eastern white cedars make good bonsai. Because of their foliage and trunk characteristics, they are best suited for larger trees- good specimens smaller than 12-15" are difficult to find and even more difficult to make into convincing bonsai. If you live in an area where cedars are native, it is well worth looking for spots where they are naturally dwarfed-usually associated with poor soils-and get permission to dig up a few. When you do, keep them in the shade for about a month afterwards and spray the foliage frequently (four or five times a day, if you can) with water through a fogging nozzle. In the second year, start fertilizing heavily and do some initial pruning as required.
Bonsai: The Journal of the American Bonsai Society/Spring 2000