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I recently came to possess a bonsai starter kit, and among the contents were some black pine seeds. The booklet included with the kit instructs me to prepare these seeds by soaking them in water for 3-5 days, then putting them on wet tissue and keeping them warm for 1-3 days, until white begins to show.

I understand that stratification can benefit black pine, however, i can't find any other source saying to keep the seeds warm: the several I've looked at online say to stratify with cold, and for longer times. The booklet/kit do not directly mention stratification, nor do they have any instructions to intentionally cool any of the seeds, despite other sources calling the process necessary for some of the included seeds (sakura).

Any advice/insight on which instructions to follow or how the included booklet appears (somewhat) incorrect would be greatly appreciated.

Rav Cone
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  • Since you have multiple seeds, try both way and see which works better for you. Could be the supplier has pre-cold-stratified them - or not. – Ecnerwal Mar 05 '23 at 19:58
  • Depending on the source of the kit, the specific variety of seed is difficult to be sure of. Different varieties want different conditions. Alternatively, the cost of a seedling isn't that large. You could go to the local garden center or similar store and get something one year old for not too much money. That way you can choose something with some character that you like. – Boba Fit Apr 09 '23 at 22:34

1 Answers1

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I'm assuming a couple of things here:

  1. The booklet did not give a botanical name for "black pine". Note that a quick internet search yielded three different species of black pines (Pinus nigra, Pinus thungergii, Pinus jeffreyi), each of which could conceivably have different germination needs.
  2. The kit includes seeds for Japanese Black Pine, which is the species Pinus thunbergii. I found references to three types of Japanese Black Pines, one of which is seed propagated. I assume that you have this species because it is often used for bonsai.

According to this site (thespruce.com), Japanese Black Pine seeds do not need stratification. Note that the germination instructions are near the middle of the page.

For a more scientific perspective, according to Michael Dirr, in his Manual of Woody Plants (Fifth Edition, p 747): "[P. thunbergii] seeds have no dormancy and will germinate immediately upon sowing."

While this indicates that, if my assumptions are correct, the kit's instructions regarding stratification are accurate, I take exception to their method of germinating the seeds, especially soaking them for five days, which in my opinion could kill them. Following both thespruce.com and Dr. Dirr's recommendations, just plant them 1/8" deep in the soil and keep them well-watered.

Please let me know if there is a botanical name included in the kit and if it is not P. thunbergii. If that's the case, then I will edit or delete this answer.

Jurp
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