Japanese maples are best transplanted when they are dormant---usually late fall through early spring if the ground does not freeze in your area.

The following information comes from Japanese Maples (by J.D. Vertrees, 2001, pp.61-62). This book also contains good information about mulching and general care:

When moving a plant to a different location within a garden, the plant must be dug with an earthen ball intact around the roots. If the plant is of any size or age, this root protection is important. It is also desirable that the planting hole be prepared in advance, ready to receive the plant with its root ball, as soon as it is dug up. Having the new planting hole ready minimizes the risk of the fine feeding roots drying out. For this reason it is imperative that, whatever method, material, or timing is used when planting a Japanese maple, the roots are not exposed to air or direct sunlight for any length of time. Such care will help prevent them from becoming desiccated, which would cause too much transplant shock and possible loss of the tree.

The planting hole should be dug slightly larger than the root mass of the plant. To enable the root system to establish itself quickly, it helps to mix with the soil organic compost, such as composted conifer bark mulch, rhododendron or azalea planting mix, or rose compost. In tight , heavy clay soils the compost helps condition the soil, while in light, sandy soils the compost assists in water retention. Sawdust or wood chippings should never be used as, during their breakdown, they use up the available soil nitrogen and render it unavailable to the newly planted tree.

The planting hole should be deep enough so that the root collar of the plant, the ground line at which the young plant was grown, is level with the ground surface. The exception to this rule applies to tight, heavy soils, like clay, where success will be greater if the hole is rather shallow so that the root system is partly above the ground level. When filling in the hole, the soil should then be mounded up to the root collar to pretect the roots from drying out. If deep holes are dug in heavy soil, it is like planting the tree in a large iron kettle with no drainage. Surely the plant will soon drown and die.

Whatever the soil conditions, the tree should never be planted deeper than the root collar. After the first season or two, the plant will find the level of root activity at which it can exist in particular soil conditions. I have observed maples growing in some surprisingly dry, shallow, and exposed conditions.

Season All Season
Date 2006-11-14
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Trees (maples and others) are attacked by various diseases and pests, but nothing that removes sections of bark on a trunk. Damage might be from larger pests such as raccoons, deer or squirrels. In the city, squirrels often strip bark from trees for their nests. You might want to:

1. Put chicken wire, barbed wire or other protective barrier around the tree. The tree will heal itself as long as the entire trunk is not girdled (that is when bark is stripped all the way around the trunk so moisture and nutrients can't flow).

2. Have an arborist look at the tree for an accurate diagnosis.
To locate an arborist in your area, contact Plant Amnesty at:
www.plantamnesty.org
or call Plant Amnesty's Referral Service Coordinator at:
206-783-9813 and leave the following information:

Name
General Location (city or town)
Phone Numbers (work, home, cell)
Email (will get the quickest response!)

Season All Season
Date 2006-10-05
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I found a series of replies to a question like yours on the University of British Columbia Botanical Garden's online forum.

The Oregon Association of Nurseries offers the following information. Excerpt:

Keeping up with the demand for "newness" means learning about and trialing different propagation techniques. That's where tissue culture, or "in vitro micropropagation," has been used as one propagation tool of many in the tool chest, said Gayle Suttle of Microplant Nurseries Inc. in Gervais, Ore. The company focuses on shade trees and shrubs. "No technique will dominate," Suttle said. "What's going to work for the industry is, number one, focusing on quality and, number two, efficiency. If you sacrifice quality for cost, then you lose."

Micropropagation helps many nurseries get a jump-start on production of new items, improve the reliability of plant performance and start with clean stock. In the area of woody plants, micropropagation has had a particular impact on the nursery industry, allowing growers to cut the time needed to establish mother blocks and meet production demand, Suttle said. Also, there are some plants where branching is hard to come by, and micropropagated plants tend to branch more. "If you can grow a plant by seed, there's nothing that beats throwing a seed into the ground," she said.

But there are plants for which normal propagation has problems -- the seed source is unreliable or unavailable, a graft is incompatible with its scion, budding problems arise in the field or roots fail to form on cuttings. Micropropagation fits as one way to keep growers successful and efficient.

"Twenty-five years ago, there was a fear that micropropagation was going to take over the world," Suttle said. "That's never been a concept that's panned out. The industry is such a variable industry, with different people doing things differently. The goal is to be successful. You can save all kinds of money, but if you have a rotten plant, no one's going to buy it. Customers may buy a cheap plant one year, but if the quality is not behind it, they won't be back next year. They'll be looking for something else."

It was plant health and survivability that drove Dieringer Nursery Company toward organic growing practices nearly 13 years ago, and those goals keep the nursery from fully jumping into use of tissue culture. The company grows rhododendrons, relying mostly on vegetative propagation with a small smattering of grafting and an even smaller sample of plants produced via micropropagation.

"Every couple of years we will bring in some tissue culture to evaluate the plant under our growing procedures, we'll get a new variety and it comes in by tissue culture," said Jeff Dieringer, president of the Hubbard, Ore.-based company.

The advantages of propagation by cuttings over other methods are exact replication of desired genetic characteristics and the more rapid time frame to finished product compared with starting from seed. Nearly all of the hundreds of thousands of rhododendrons Dieringer nursery handles in a year are grown using vegetative propagation, while maybe only a couple hundred are started from in vitro micropropagation.

"It's a way to introduce a plant, but we don't get tissue culture starts and turn them into production plants," Dieringer said. "We watch that plant, its habits under our growing condition for three to four years to see if it exhibits normal growth. We do vegetative cuttings then, if they don't exhibit any juveniles."

The Miller Library has several titles on micropropagation in general, but I did not find anything specifically addressing use of this method with Acer palmatum. A good general text with several chapters on in vitro culture is A Color Atlas of Plant Propagation and Conservation by Bryan G. Bowes (New York Botanical Garden Press, 1999).

Season All Season
Date 2007-06-23
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Interestingly enough, Acer palmatum is listed as possessing medium-high wind resistance by University of Florida Extension in their trees-and-hurricanes information.

The following comes from Mississippi State University Extension: The U.S. Forest Service conducted a study after Hurricane Camille devastated the Coast in 1969. The study indicated that the best wind resistant trees are compact and have major tap roots. Trees with a tapered trunk have a low center of gravity and are more stable.

I would be concerned about scorching from exposure to hot wind, and damage from winter wind even if the tree is not likely to lose limbs. Here is what J. D. Vertrees's book, Japanese Maples (Timber Press, 2001, 3rd ed.) has to say: A spot with a constant strong wind will misshape the plant and may burn the leaves. In winter, the wind-chill factor may cause bark and cambium damage (...) In areas of strong marine breezes, leaf damage from salt deposits may occasionally occur. Anyone growing plants under such conditions should be familiar with the necessary protection and the need for periodic washing of the foliage with fresh water. (p. 63)

In any case, North Carolina State University Horticulture has information on Acer palmatum cultivars. University of British Columbia Botanical Gardens offers additional information.