Pruning Japanese Maples

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 lacy 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 [but not a bowl cut]–it will grow back.

When pruning upright maples you want to remove branches from the inside that crossover. If you have a ‘V’ shaped trunk the inside crossover branches are those growing inside the ‘V’. If you collect Japanese Maples you have probably noticed that most grow in the ‘V’ or vase shape. I recommend spring pruning because this is the time you can see the dead branches that did not make it through the winter. This is mother nature’s pruning process for branches with leaves that no longer received sunlight on the inside. These small interior branches die as the maple grows. A different pruning technique is needed for the Mikawa yatsubusa type maples. The leaves are attached to the branches in overlapping layers and when insufficient sunlight reaches these leaves they turn yellow and brown. I use my hands to remove these leaves during the late summer months. Since you remove mostly leaves or tiny branches pruners are not necessary. By cleaning out your Mayday, Mystic Mikawa, Japanese Princess or Mikawa yatsubusa from underneath you prevent the chance for mold or mildew to form on the dead and dying leaves.   

Additionally, customers send me photos of their maples and ask about 3′ of new growth that stick out from the structure of the maple. The key is not to let these branches get that long. Prune these branches at about 6″ to 8″ from the main structure of the maple, don’t let your maple spend its energy growing something you don’t want. This also applies to branches and leaves originating below the graft. Below the graft is root stock which is usually a green leaf seedling. Always remove this growth.

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. Don’t use bleach to sterilize as it 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 and keep your shears clean. If your pruners are made from ‘stainless steel’ and have gotten dirty and/or rusty over time – get a jar or glass and place your pruners sharp side down and open on the bottom. Fill the container with Hydrogen Peroxide straight out of the bottle to the top of the blades. Leave your pruners in the Peroxide a few hours or overnight and the blades should be clean and free of rust the next day. Repeat as needed.

If you have questions not answered in this section – Pruning  Japanese Maples – please call or email me.

Sam, the Maple Lady.

Phone 360.263.2662