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.