Sargent's Juniper - Juniperus chinensis sargentii
General information: In Japan, this tree is
called "shimpaku" and thus it is often referred to in
western countries as "shimpaku juniper". The shimpaku is
native to Japan, the Kurile Islands and the Sahalin
peninsula. Its natural habit is prostrate and it prefers
rocky, well-drained soils. In its natural range, it is
most often found growing near the sea. The foliage is
needle-like on young trees and scale-like on older
trees. The fruit is a small, hard, bluish berry.
Lighting: Full sun.
Temperature: Wide range of temperatures, will
Watering: Spray the foliage with water daily
during the growing season. Water when the soil is
moderately dry (to a depth of 1/2 to 1 inch) but do not
let the soil dry out completely.
Feeding: Simon and Schuster's recommends
feeding from early spring to autumn ever 20-30 days
using a slow-acting organic fertilizer. If you prefer to
use chemical fertilizers, apply a half-strength solution
every other week of a reasonably balanced fertilizer,
such as Peter's 20-20-20. You may wish to alternate with
an acidic fertilizer such as Miracid. You should not
fertilize during the hottest part of the summer
(July-mid August in the northern hemisphere), or if the
tree is weak or has recently (2-4 weeks) been repotted.
Pruning and wiring: Reduce the roots
gradually, removing no more than one third of the roots
at each repotting. To develop the foliage, pinch out the
tender new shoots using your fingers. Do not use
scissors, as the cut needles will turn brown. Pinching
must be done continuously during the growing season.
Prune undesirable branches (especially those growing
straight down from their parent branch) when repotting
or during the growing season. Wiring is best done in
autumn or early winter, so that the branches
can become accustomed to their new position while the
tree is dormant. Wiring done at other times must be
watched carefully for signs of wire cutting into the
bark, and must be removed immediately if this happens.
If necessary, the tree can be re-wired after removing
the old wire.
Propagation: No information available.
Repotting: Repot young trees (up to 10 years)
every other year. Repot older trees every 3-4 years.
Repotting is best done in spring. Junipers can also be
repotted in autumn if necessary, since they enter a
period of renewed root growth at that time. Extensive
root pruning in autumn is probably not a good idea,
however. Simon and Schuster's recommends 60% soil, 10%
peat, and 30% coarse sand. Rémy Samson recommends 1 part
loam, 1 part leaf mold, and 1 part coarse sand. Peter
Chan recommends 1 part loam, 1 part peat, and 3 parts
coarse sand. The tree should be protected from wind and
direct sun for a month or two after repotting.
Pests and diseases: Junipers are a favorite
victim of red spider mites. If the tree appears weak,
with yellowing foliage, it may have spider mites. To
check for spider mites, hold a sheet of white paper
under a branch and gently shake the foliage. If the
paper comes away with many small dots that move, it has
spider mites. To combat spider mites, spray with
insecticidal soap or a nicotine solution (which can be
made by soaking tobacco in water overnight).