- By Ken Schultz

Usually I follow the common name with a scientific – or vice versa. But this is it, both. It’s Cot-o-nee-as-ter, not Cotton Easter, which I’ve frequently heard over the years. There are a wide selection of Cotoneaster varieties. Unfortunately, pre-bonsai varieties tend not be hardy to this zone, and when planted in a pot some of the locally available landscape materials object to root pruning. This must be why I’ve avoided Cotoneaster as the tree of the month subject for so long.

Cotoneater are usually trained as nifty little “apple trees”; their white flowers and red fruit are size proportionate, and their natural branching is arched toward the ground make them an ideal scale model. Unfortunately, they also get fire blight just like apples. However, when fire-blight strikes a shohin or mame’ bonsai is likely to die before the fire blight can be removed.

In the landscape Cotoneaster are used as ground cover or low filler shrubbery. I have seen and bought, cascade pre-bonsai. But they have secummed to blight or perhaps weren’t hardy to our zone. I’ve also tried my hand at converting nursery stock, with similar results. However, I keep going back. They are readily available and aren’t pricey at all. The trick in selection is finding one that is single trunked so that it makes a believable tree. The next issue is that they frequently have large branches near the top of your bonsai; keep that in mind when you cut off the big branches to keep the smaller twigs as your future tree. Colin Lewis says that the regular branching pattern make them a good subject for beginners. Remember England is a zone 6 or 7; so they’re easier to cultivate there.

Since they are a landscape plant, they will tolerate a good deal of sunlight. Though because you are likely to be trying to reduce the root ball to make it into a credible Shohin or Mame’, you will find that you cannot let them dry out. In addition, they cannot be rushed into a reduced rootball size, as a result mine tend to be over potted. While they do not like wet feet, you may want to keep some of their original soil in your mix to help with moisture. I am certain that in the winter you will need to provide the roots with protection from freezing. If you have a coldframe, use it. I am tempted to try keeping one inside to see what that would do. Tomlinson says that Cotoneaster microphyllis is good for indoor bonsai. The literature notes that in cold climates they are deciduous, and in warm climates they are evergreen.

In keeping with the “does not like to dry out” note: repotting is suggested annually. And a further caution is that they do not like to be bare rooted. The literature also says do not remove more than 1/3 of the roots. The color of pot should be a dark blue with a glazed finish, though lighter blues or dark greens also make good choices. Since the trunk is likely to be curved, an oval pot will probably be the shape to use. Propagation is best from air layering; nick a branch and stick it in soil near the plant to you are using as the stock materail. Soon adventurous roots will form and the branch can be removed from the parent plant.

During the growing period, keep your eye on the new stems; they seem to be irresistible to aphids. Inside you may have trouble with mealy bug. Use ½ strength liquid fertilizers (with a higher P) during the growing period. Because they are a shrub, pinch out all unwanted suckers, and shorten new growth to one or two sets of leaves after they lengthen to 3”. Outdoors wiring should be done before bud break. After they leaf out, wiring without damage to the new growth is very tricky. The bark is a dark grayish color, but be careful, wire can easily damage it.