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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 temperaturs, will tolerate freezing.
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).
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Before
After
Image of tree prepared by Ben Oki