Shimpaku is also known as the Chinese Juniper, an excellent choice for bonsai. This evergreen is highly tolerant of various soil types. Interesting, Shimpaku is also dioecious, meaning it has separate male and female plants. This naturally, irregular shaped tree that grows in mound shape. The nice thing about using the Shimpaku tree for bonsai is the year round foliage with dark, green needles, beautiful to look at and soft to touch.
Because the Shimpaku is so easy to grow and maintain, it is perfect for beginner bonsai growers. With more than 500 species of evergreen in the Juniper category, you will certainly find the exact one that suits your needs. Typically, the Shimpaku tree in Japan has been collected from mountains, dating back more than two centuries.
The Shimpaku does best in full sun although those with scale-like foliage do like a little bit of shade. In the winter, you want to protect the Shimpaku from frost. When growing this type of tree indoors, the key is to make sure the tree has lots of good lighting, excellent humidity, and adequate air circulation. Without this, you would have a very difficult time growing it.
To water the Shimpaku, you want to keep the soil barely moist. Watering too much could lead to root rot, which is a problem the Shimpaku is prone to developing. In addition, you should mist the foliage several times a week to help keep pores free from dust in that this tree needs to breathe. To feed this bonsai tree, you want fertilizer every other week, containing high nitrogen. This should be done from the early part of spring to midsummer. Then from late summer through the winter months, feed the Shimpaku with low nitrogen fertilizer.
The Shimpaku needs to be pinched back continually throughout the growing season, helping to keep the foliage dense and compact. The key here is to use only your fingers, never scissors that would cause the foliage to turn brown. Then, do not pinch anything off one month after any visible growth is seen in late spring. Then, you want to thin out the foliage, helping to reduce the volume of older growth in the summer.
Now for repotting your Shimpaku, this should be performed every two years until the tree reaches age 10. At that point, you would only repot as needed. The best type of soil for this bonsai is soil that is free draining. Just make sure all stone or grit used in the soil mix is cleaned prior to using. This will get rid of any alkaline deposits that would cause stress to the tree.
To propagate the Shimpaku, you can air layer or use root ripe, woodcuttings in the fall. When it comes to styling for bonsai, the Shimpaku works exceptionally well with all styles with the exception of the broom. Then, this particular tree is virtually disease free. However, you would want to check occasionally for scales.