Great talk from Mark Kerry tonight on Junipers, a wealth of knowledge and good information was provided with a follow up demonstration on pruning junipers and discussion on the junipers brought in by club members.

Junipers tolerate full sun but prefer semi shade and high humidity. Mark uses a soil mix of Akadama and kiryu 2:1 which is free draining as Junipers are susceptible to root rot with over watering. He advises to repot as they start to grow or green up in the Spring but to only carry out minimal root removal. He suggests to feed April -Sept and watering well in spring and summer as well as the foliage to aid to clean the leaves but to ensure the soil drains.

Junipers are a hardy species, so need limited winter care but if you leave outside place them under a tarpaulin to control watering if it is a wet winter. They sometimes will have a bronze foliage which is natural in winter but if you are showing then protect from frost so they remain a dark green colour to their foliage.

He advises that you can wire all year and also that do not buy juniper if you don’t like wiring as they will need to be wired to get the desired effects for styling and shaping in general. With regard to pruning, do not remove more than 25% at once as you will get juvenile foliage not scale foliage. Also that you should use scissors not pinching as this causes browning. It is a myth that you should pinch junipers and this is not a great technique. Also if you are working on needle junipers then use very sharp scissors to avoid crushing needles. Source –

For annual maintenance start with the spring when you repot, and then start feeding after 6 weeks with organic feed initially as opposed to chemical feed. Then in summer start pruning & feeding until September. In winter stop feeding and reduce watering, so water sparingly to avoid root rot.

With regard to propagation they can be grown from seeds but do not let your tree set seed. They can be grown easily from cuttings, heal cuttings especially but these can take a year to root. Air layers work well started in late spring and grafting is very successful on Junipers. Grafted branches or shoots widely used in Japan on species using Itiogowa as this has small tight foliage.

Junipers do suffer from pests and diseases and the most common are spider mite which can be treated with systemic insecticide as well as conifer mite. They also get scale insect which can be picked off or treat with systemic insecticide. Watch out for brown foliage but this is natural for older growth on trees caused by being shaded out by dense growth so clean out to create aeration in crown.

Juniper species commonly used in bonsai:

  • Sargentii – Chinese junipers
  • Itiogowa
  • Sabina
  • Blaaws – bluish tinge to foliage
  • San Jose
  • Ridida – sharpe needle foliage
  • Procumbens

Tend not to use:

  • Variegated
  • Squamosa
  • Avoid coarse foliage ones hard to refine

For styling juniper bonsai it is wiring predominantly as they have a bushy habit with flexible branches. You will need to remove foliage to aid wiring and you wire all branches and wire into fan shape. Wire established woody growth not green shoots.

Deadwood on Junipers is very natural and often bleached to mimic nature using lime sulphur. The bark is craggy but use sand paper to get smooth bark and the idea is to create contrast between live and deadwood. Junipers lend themselves to many styles from cascade, semi cascade, clump, raft to informal upright and adapt the tree species to the style. You can also do a wrap around where you literally wrap live saplings round juniper deadwood. It is hard to do and slow to callous well but can carve channels to get convincing image.

Carving of Junipers is a slow process and do not carve out sap lines all at once as this can lead to the tree struggling. You can cut sections and let them recover but remember to keep in shade after cutting. Mark then shows us a series of examples by Kimura and shows that Juniper work at all sizes as foliage suits all scales and they are very versatile species of trees.

Key features of Junipers are often the contrast of the deadwood and live foliage and you can find examples in the wild to show that Junipers actually grow like that naturally and that the deadwood can be subtle or dominant. Mark goes on to reference a series of case studies courtesy of Lee Verhorevoort Bonsai and a link to his website:

Mark likes Maples and Junipers especially when it comes to styling junipers and he recommends two specific books that he has found to be useful.

  • Junipers by Bonsai Today
  • The Art of Bonsai design by Colin Lewis