Japanese maples can handle hot climates with adequate water and protection from hot drying winds. However, Japanese maples may be damaged or even killed by extremely cold temperatures. Care should be taken to protect young plants and container grown plants when outside temperatures drop below 16 degrees F. During cold winters [temperatures in the single digits] mulching the base of the tree to protect the root ball from freezing is critical.
All Japanese maples like consistent watering. In fact, Japanese maples prefer a loose well-drained soil. Good drainage is critical. When a Japanese maple does die, root rot from poor drainage is usually the culprit. Areas with clay soil require, not only that the soil be amended, but that the tree be planted higher than the surrounding soil. Mounding the soil and planting the tree so that the roots can stay above the clay soil is important. Remember, no matter how large a hole you dig in the clay--you are really creating a bathtub. Water will run along the surface of the clay and end up filling the bathtub, which will drown your tree. It may not happen the first or second year, but it will happen. Please take the time to provide an environment where the tree roots can stay on the dry side. [Though we cover the topic of good drainage under planting instructions, we feel we cannot over emphasize this important factor.]
Ground watering from a hose or drip irrigation system is recommended, rather than overhead watering from sprinklers. In the hot afternoon sun, overhead watering can cause the leaves to burn or 'crisp' because the water on the leaves acts as a lens to focus the hot burning rays of the sun. If you must plant your maple where an overhead sprinkler will provide the source of water, do not water during the heat of the day; early morning is best. If the leaves of the maple do burn or begin to crisp and fall off, it does not mean that your maple is dead, though it may look like it. In time the leaves will grow back. Stripping the dead leaves off will help rejuvenate the tree.
Many gardeners are afraid to prune their trees and shrubs. All Japanese maples need some pruning, especially when young to help establish their structure. Lace leaf maples need more pruning than other varieties to keep them looking Japanese instead of a big red, shaggy mound. Pruning should thin out the number of smaller limbs and open the tree structure for air flow. The ideal look for a lace leaf maple will allow the viewer to see some of the structure of the trunk and bark as a contrast to the beautiful lacey leaves that flicker when the wind blows. The best time to prune your maple is in the spring when the tree is just forming buds. Remember the new growth will add another twelve to fifteen inches to each limb during each growing cycle. The weight of the new growth causes the weeping effect, so annual pruning of young trees is recommended to help establish their shape. Don't be afraid to prune--remember its like giving the tree a haircut--it will grow back.
Important tip: Use rubbing alcohol and not bleach to sterilize your shears when you prune. We carry a small jar with a lid and regularly dip the pruning shear blade into the alcohol to keep it sterile. Also, the alcohol evaporates quickly from the blade. Bleach on the other hand can irritate the cambium layer of the tree. Using rubbing alcohol on your pruning shears helps to prevent the spread of disease from one plant to another.