Shimpaku Juniper. This little Juniper is one of the most popular conifers in Japan as a bonsai subject. It is low and compact and slightly irregular, hence it lends itself to training. Grow it in full sun with good drainage. The major problem with Junipers are bag worms in mid to late summer. This is a moth whose larvae can totally defoliate a plant, which then makes cocoons out of its tiny branchlets.