The coral bark maple is a slow-growing, medium-sized Japanese maple with beautiful aesthetic qualities that make it prized for landscape use. During the spring and summer, its foliage is a light yellow to almost neon green color, which cannot be missed and contrasts nicely with every dark green plant surrounding it. These leaves turn to a shocking yellow or salmon-red color in autumn. When most trees shed their last burst of color, the coral bark maple shows you where it gets its name at leaf drop. During the other seasons of the year, the tree has hidden prized bark, a pretty dark pink color dazzling when set against a stark winter backdrop. With these aesthetic qualities, its adaptability, and a slow growth rate, the coral bark maple is perfect for adding visual interest to a landscape that needs a specimen to draw the eye. While not difficult enough to make you throw up the white flag before starting, it is not without its issues. Following the guidelines below will help make caring for your coral bark maple a much more pleasant experience.
Light
Light is one of the areas that are tricky with coral bark maple. If you go into a nursery, the tag says it does well in areas from full sun to partial shade. There is a dilemma here, though, because you need to know a little more information. New leaves on Sango Kakus, especially juveniles, are prone to sun scorch, but planting your tree in full sun will give you the best fall coloration. There is, fortunately, a solution. While the the tree is young, in the early spring you can set a shade screen over smaller trees until they become mature leaves that can handle the full sun, at which point you can remove the screen. In the fall, you will have all the benefits of a tree planted in the full sun without damaged foliage.
Soil
Your coral bark maple is very adaptable to various soil conditions, and this should not be one of the areas that give you any issues. It prefers moist, well-drained soil but will tolerate heavy clays, sands, and loams all the same. It does not do well in soils with a high pH, instead favoring soils ranging from slightly acidic to neutral.
Water
One very attractive feature of the coral bark maple is its drought tolerance. Once the tree matures, this Japanese maple makes an excellent choice for people looking for plants for water-wise gardens or those who live in areas prone to drought. It is important to water your tree to establish a robust root system. You can do this by watering your tree weekly during its growing season at a rate of 10 gallons per inch of trunk diameter measured by a caliper at chest height. Doing this for the first two years will ensure that your tree is nice and healthy.
Temperature and Humidity
Being native to Korea and Japan, the coral bark maple does not tolerate extreme heat or humidity very well. It prefers moderate temperatures with warm summers that are not too hot and winters that are not too cold. It is not incredibly frost tolerant but can withstand some early frosts if placed in a sunny location. Sticking with the recommended growing zones of USDA 6b to 8a is the safest way to ensure a happy maple.
Fertilizer
It would not be necessary to fertilize most native maples, but an ornamental Japanese maple like the coral bark maple is an exception. Before fertilizing any plant It is good practice to test your soil and see if there are any deficiencies or over concentrations of nutrients. If the soil shows that it is deficient or average you can amend it to compensate in a certain direction. In the case of the Sango Kaku, as the foliage and branches are the traits you looking to accentuate, you will want to use a fertilizer with a higher nitrogen concentration. You can tell a fertilizer is higher in nitrogen by looking at its NPK number.
Pruning
Naturally, your maple will take on a rounded form, but along the way, it might need your help, or you might want to shape it to fit your landscape or slow its growth. Whatever the result, you need to go into it knowing the plan, having the tools, and having a vision for the result. To do the pruning, you will want the following tools: hand pruners, loppers, a pruning saw, and alcohol to clean them before and after.
Rounded Shape
Pruning your tree to maintain its natural shape is just a matter of the maintenance you would provide any deciduous tree as it establishes its form over the first few years of its life. After the first year, you will cut off branches to establish a dominant leader. In subsequent years, work to establish form by cutting any intersecting branches that point inward or intersections that are too sharply angled all the time, looking to remove dead or damaged branches. Continue this until you cannot do the work safely without a ladder. You want to call in a licensed arborist to take over the task when you get to this point.
Keeping the Tree Small
Your tree naturally grows slowly, so this might not be an issue, but if you are concerned about your tree outgrowing your yard, you may want to rein it in before it gets too late and too costly to fix. Trimming the tree is a bit complicated, so you may want to bring in a pro and call in a licensed arborist at this point. But if you are confident in your abilities, it is doable as long as the tree is not too large. If your tree is small enough to reach the top grab a pruning saw and some pruners, it is time to learn to do what is referred to as the drop-crotch pruning. What you should not to do is “top” the tree. Topping a tree is the pruning of large upright branches between nodes. Instead, you want a drop-crotch, which uses cuts that are precisely placed. First, you will find a lateral stem at least one-third the diameter of the trunk or leader. Above this location, at the angle of the lateral branch, you will make your cut into your trunk; this angle should be no more than 45 to 60 degrees. Avoid lateral branches that are horizontal. Repeat this process yearly on all the vertical growth, and your tree will stay as small as you desire for as long as you keep at it.
Propagating Sango Kaku Japanese Maple
Specific cultivars of Japanese maples can only be grown by cuttings, as any planted seed will revert to the original Acer palmatum. You can propagate coral bark maple yourself by cutting, but it will not have the protection of the straight species. To propagate, fill a pot with thoroughly moistened organic soil-less potting mix. Next, get a clean pair of pruners and take a series of cuttings from semi-soft wood branches. The wood should be not completely herbaceous but not woody either. Supple is a good word for the texture of the branch you want. Cut the branch above a leaf node and wrap it in a wet paper towel until you are ready for the next step. You’ll want to remove the lower leaves of your cutting and trim off the stem to the leaf nodes of the leaves you just removed. Dip the stem in a rooting hormone and let sit for a few seconds. Use a pencil or dibbler to poke a hole in the potting mix and insert the cutting into the hole. Pack the mix down firmly and place it in a spot that is consistently between 60 and 80° F and receives indirect light.
Common Pests and Plant Diseases
The coral bark maple is relatively disease resistant and has few serious pest issues. The issues it does have will not threaten the tree’s life and only cause a nuisance and some cosmetic issues. Pests like scale, maple worms, leafrollers, and leafhoppers aphids are possible but not especially concerning. The only concerning disease you might encounter with this Japanese maple is Anthracnose, a group of related fungal diseases that typically causes dark lesions on leaves. Anthracnose symptoms vary, but on the coral bark maple the leaves become curled and distorted, with only a portion of each leaf dying. Fungicides only protect unaffected tissue; all other affected tissue (leaves, twigs, and branches) should be destroyed or burned during fall or winter.
