Shimpaku Juniper care, feeding and ideal soil mix

I have had great success over the years with most subtropicals and
deciduous trees but considerably less with pines and junipers. I am
especially interested in getting better with Shimpaku junipers.
I read your recent post about propigating them and it seems that no organic in the mix is the way to go.What about sun, feeding and watering? How critical is FULL SUN exposure?

I have been trying to rejuvenate an ailing shimpaku planted in the
standard Brussel’s soil mix but with a bit more of the rock component.
His is a man made aggregate similar to akadama. This tree is currently housed
within a state of the art greenhouse which is shaded with a silvery
mesh and rather more humid inside than outside. It is in Little Rock,
Arkansas which features mercurial weather changes.

Whatever you can tell me about the best environment, care and feeding of
shimpakus , including when and how much I can trim them is very much appreciated. Also, can old greying foliage come back to green or does it just have to be trimmed off?

Dane Buxbaum

It sounds like there are a few things going on here - here are some basics for junipers and pines.

  • Junipers do well outside. Is there a reason for keeping the ailing tree in a greenhouse?
  • It’s easier to keep junipers healthy when they get at least some direct sunlight.
  • Only water the soil when it becomes dry:
  • Hold off on feeding until the tree is healthy
  • Hold off on trimming or wiring until the tree is healthy
  • In general, old, greying foliage will not recover, though overall tree color can improve as the tree becomes healthy
  • Lava, pumice and akadama make for a great soil mix. Repotting the tree in the dormant season is a good time to replace about half of the current soil with the new mix. The other half can be replaced at the next repotting, 1-2 years later.

So can I trim off the old stuff next dormant season? How severley can I trim?

It’s hard to say what to trim without seeing the tree.

If the tree is really weak, I wouldn’t touch it. If it’s growing well, old foliage could be thinned. General cutback for shaping can happen once the tree is healthy again.

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