Pruning Japanese Maples
Maintenance – Pruning
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 or green, shaggy mound. Pruning should thin out the number of smaller limbs and open up 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. For weepers it is the weight of the new growth on a young branch that causes the weeping effect, so annual pruning of young maples is recommended to help establish their shape. Don’t be afraid to prune–remember its like giving your maple a haircut–it will grow back.
Important tip: Use rubbing alcohol and not bleach to sterilize your shears when you prune. I carry a small jar with a lid and regularly dip my pruning 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 maple. Using rubbing alcohol to sterilize your pruning shears helps to prevent the spread of disease from one plant to another.
Care and Maintenance
Japanese maples JMs can handle hot climates with adequate water and protection from hot drying winds. Even with adequate water during the first summer your maple will show burned brown leaves. Over watering is not the answer and it can actually be detrimental to the health of your maple. The reason for the burned dry leaves is that your maple has yet to establish new roots which will allow more water to reach the leaves. So please don’t freak out over brown dried leaves that first summer. And definitely don’t over water. If your maple begins to show wilting leaves it means you are drowning the roots. The first instinct when a plant wilts is to give it more water. Just the opposite for JMs.
Cold winter climates pose a risk for JMs unless they are protected from extreme cold temperatures. Care should be taken to protect young maples and container grown maples when outside temperatures drop below into the teens or single digits. If the roots reach 16 degrees F then the maple will die. During cold winters [temperatures in the single digits] mulching the base of the maple with 3″ or 4″ of material such as bark chips is recommended.
All Japanese maples like consistent watering. In fact, Japanese maples prefer a loose well-drained soil. Good drainage is critical. When a JM does die, root rot from poor drainage is usually the culprit. Gardens 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 maple 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 basically 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. Once the maple is planted then a watering schedule should be developed and followed. In hotter areas watering once a week may be needed. I recommend every two weeks with the hose on a trickle to direct the roots to grow down and not on the surface. 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.