Pinus thunbergii (Japanese black pine)

Propagation

Seed

• Soak in warm water for 1 day
• Store 1 week at 5C
• Sow in spring
  • Use a tray with a mesh at the bottom like a pond basket
  • Use a draining mix with some water retention capacity
  • Put a mesh above the tray to protect from rodents and birds

Development

Year 1

• Spring
  • Sow the seeds as detailed above

Year 2

• Spring

  • Repot the seedlings in small individual containers

• Fall

  • Wire the trunk to create movement (3 mm aluminum)
  • Remove all side buds at the top node except one to prevent shading the lower part of the tree and keep the central bud for the trunk extension
  • Thin out unnecessary needles for back budding to also prevent shading

Year 3

• Spring
  • Repot from small container to pond basket to setup the roots
• Summer
  • Remove wire when it is starting to bite
• Fall
  • Thin out unnecessary needles and all except one side buds at the top of the tree like last year
  • Cut lower needles short
  • Wire and bend over the sacrificial branch to avoid shading the lower part of the tree
  • Prune lower branches that are too long or wait until decandling time next year

Year 4

• Spring

  • Repot to the same pond basket to inspect and correct the roots

• Summer

  • Decandle lower branches

Year 5

• Spring

  • Remove unnecessary branches

• Summer

  • Decandle lower branches

Year 6

• Summer
  • Decandle or cut back lower branches

Calendar

There are three periods in the year to work on black pines:

• Spring: repotting (when buds begin to swell)
• Summer: decandling (earlier in colder climate)
• Fall: thinning

Links

• https://bonsaimirai.com/species/japanese-black-pine-bonsai
• https://bonsaitonight.com/2016/08/17/grow-japanese-black-pine-seed/
• https://bonsaitonight.com/2016/07/22/decandling-black-pine-bonsai-overview/
  • Cool climates (Seattle, Pacifica) – decandle late May
• https://bonsaitonight.com/2019/05/07/teach-yourself-bonsai-2-how-to-create-a-bonsai-calendar-japanese-black-pine/
• https://bonsaitonight.com/2022/06/10/bonsai-development-series-26-focusing-growth-in-a-single-sacrifice-branch/
• https://phutu.com/black-pine-creation/
• http://www.bssf.org/articles-and-stories/care-of-japanese-black-pine-stages-of-development/
• https://youtu.be/7YhvVDB_b_0 by Jonas Dupuich
• https://youtu.be/f0fe6v7X0MQ by Harry Harrington