Japanese Maple Highlight: Acer palmatum 'Sango kaku'

Welcome back! In this week’s edition of Maple Ridge Musings we are going to be discussing the very popular Japanese maple variety, Acer palmatum ‘Sango kaku’. ‘Sango kaku’ is most commonly referred to as the coral bark Japanese maple. This name describes the most distinguishing characteristic that this tree has. In the wintertime the bark of ‘Sango kaku’ develops a bright, coral red that is quite striking and noteworthy. ‘Sango kaku’ is an upright growing Japanese maple with a tall and slender mature shape. Acer palmatum ‘Sango kaku’ is one of the most popular Japanese maples there is due to its strong growth habit, its excellent fall color, and its famous coral bark color. We try to grow as many ‘Sango kaku’ Japanese maple trees as we can.

Acer palmatum ‘Sango kaku’ has very small, palmate leaves with five to seven lobes. These leaves are a light green with a pink hue when they first emerge in the spring. This light green color to the leaves lasts all spring and into the summer before the leaves darken somewhat during the peak of the summer. Occasionally in full sun the leaves will even have a yellow or orange cast to them. By the time fall arrives, ‘Sango kaku’ will have bright yellow foliage with a mix of orange and red leaves at times. These leaves will sometimes transition fully to orange or red late in the fall before they completely fall off the tree. Acer palmatum ‘Sango kaku’ is known for its bright coral red bark, but the attractive foliage is certainly nothing to sneeze at.

The coral red branches of Acer palmatum ‘Sango kaku’ put this Japanese maple tree in the Red Wood category of Japanese maples according to the official Maple Society classifications. The coral red color is most prominent and striking the winter but given the right conditions you can usually see some red color on the bark throughout the year. Spring is often an attractive time for ‘Sango kaku’ because the bark is still very attractive from its winter show, and it is contrasted with the fresh green leaves of spring. Usually, the summer bark will be greener with reddish hues, but there are often smaller twigs that are still bright red. By fall, the bark of ‘Sango kaku’ is transitioning back to its winter bark color and really shows off along with the golden yellow fall foliage.

One issue with the popular coral bark Japanese maple variety is that the bark color sometimes fades over time. Many mature specimens won’t show off the bright coral bark in the winter anymore. However, even on these specimens the younger branches will still show the bright coral color. We’re also talking about trees that are twenty years old or more that lose their bark color. To get the best bark color on you ‘Sango kaku’ coral bark Japanese maple you want to plant your tree in full sun to partial shade. The sun brings out the red color in the bark in the same way that it brings the red color out in red leafed Japanese maples. In hotter climates, it is also ideal to provide ‘Sango kaku’ with a little afternoon shade to avoid burning.

Acer palmatum ‘Sango kaku’ is a tall and slender growing Japanese maple with a fast growth rate. ‘Sango kaku’ will typically reach about 16 to 18 feet tall in 10 years. This is what we refer to as its mature size. However, as with most trees, ‘Sango kaku’ will continue to grow as long as it lives. I have seen multiple ‘Sango kaku’ specimens that were north of 30 feet tall, but they were each at least 40 years old. ‘Sango kaku’ is also a somewhat narrow growing tree that only gets about 8 to 10 feet wide at maturity. Even these old specimens I referred to were only about 15 feet wide at the canopy. ‘Sango kaku’ is a very fast-growing Japanese maple especially when young. Young ‘Sango kaku’ trees can grow up to two feet in one year. This young, fast growth can sometimes result in leggy looking branches. These branches will typically thicken up and strengthen, but early pruning can also be very beneficial in developing a nice shape to the mature tree. I generally describe the growth rate of ‘Sango kaku’ to be about one foot of growth per year. Acer palmatum ‘Sango kaku’ is the perfect tree for someone that needs a tall tree that doesn’t take up too much space.  

Acer palmatum ‘Sango kaku’ is hardy to zones 5-9. ‘Sango kaku’ as with most Japanese maples should be planted on a mound with well-draining soil. ‘Sango kaku’ should be planted in mostly sun with a little bit of afternoon shade to produce the best colors. ‘Sango kaku’ can be planted along with green bark varieties such as Aoyagi or Kawahara no midori or yellow bark varieties such as bihou, gold digger, or Dixie Delight for a variety of bark interest trees in the winter. There are also a multitude of other coral bark Japanese maples with different sizes and colors such as ‘Wildfire’ and ‘Japanese Sunrise’ that could be planted along with ‘Sango kaku’.

Acer palmatum ‘Sango kaku’ and other coral bark Japanese maple varieties are a little more susceptible to fungal diseases such as pseudomonas than other Japanese maples. This means that the typical precautions to prevent such diseases are even more important when dealing with coral bark Japanese maple varieties. It is imperative that ‘Sango kaku’ is planted on a mound with well-drained soil so that its roots are never sitting in too much water. Fertilizing should also be done in the spring with a low nitrogen fertilizer. ‘Sango kaku’ is a fast growing Japanese maple on its own and does not need too much growth to be pushed, especially late in the year. The younger stems need time to harden off before freezing temperatures arrive. This will help keep your ‘Sango kaku’ Japanese maple tree healthy and strong.

Acer palmatum ‘Sango kaku’ is an old cultivar dating back to the 1800s, though its exact origin is unknown. The name ‘Sango kaku’ means “coral tower”. Sango translates to coral while kaku translates to tower. This is a fitting name given the shape of this cultivar as well as the coral red color of the bark. Used to be known as ‘Senkaki’ and it is synonomous with ‘Ebi-no-hige’. ‘Sango kaku’ is also sometimes known as ‘Cinnabarinum’ or Cinnabar wood maple. ‘Sango kaku’ has also been mistakenly referred to as ‘Corallinum’, which is a completely different variety. ‘Corallinum’ is named for its coral red spring foliage rather than anything to do with its bark. ‘Sango kaku’ is probably referred to more frequently as the coral bark maple than by its actual name, but no matter what you call it, Sango kaku is a must have for a complete, four seasons landscape.