Blue Juniper - Juniperus
General Information: This juniper is notable for its striking
blue-gray foliage. A number of varieties exist, including 'Meyeri', 'Blue
Carpet' and 'Blue Star'. Blue Carpet is a prostrate variety that is
especially suitable for cascade and semi-cascade styles. Other varieties
can be used for any style other than broom.
Temperature: Wide range
of temperaturs, will tolerate freezing.
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: 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. 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
Prune undesirable branches (especially those growing
straight down from their parent branch) when repotting or during the
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
Propagation: Cuttings can be taken in spring.
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. Use a good quality bonsai compost, and add 20% extra potting grit.
The tree should be protected from wind and direct sun
for a month or two after repotting.
Pests and dseases: 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
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