Dormancy Period in Japanese Black Pine?

Hello Everyone,

I’m a new member to the forum and am toying around with growing some Japanese Black Pine in a controlled growing environment. I was curious if anyone had any insights regarding the dormancy period for JBP and whether skipping the dormancy period all together would have a detrimental effect on the tree.

Kind Regards,


Yes it would be detrimental to the tree because without a dormancy period the tree would eventually exhaust its resources and die. A university in the states did a study with Ponderosa Pines and climate change where they kept the trees in a controlled environment with the same temperature all year round. The trees died after 3 years.
I’ll find the link and post.
Patience, Just let the trees grow. There isn’t an “express lane” in the art of Bonsai :evergreen_tree::metal:t2::grinning:

Thanks for the reply, by no means am I looking for an express lane. Ryan had mentioned that they grow extremely well in the tropics potentially putting out 3 flushes of growth. As far as I can tell plants in the tropics do not really have a dormancy period so I was just looking for some clarification.

I guess that leads well into my next question however, what is the minimum dormancy period and is it impacted more by the number of hours of light or temperature?

Thanks again,


I will say I think it is impacted by temperature and light equally. I know that is how it is in almost all other trees. You can’t bring a tree out of dormancy with just one, but both are required to get a tree out of dormancy.

Awesome! Thanks for the reply Nate

I live in northern New England. Began growing Mikawa Black Pine from 1 year old seedlings 9-10 years ago. Store them in my unheated garage from end of November to early April. I find they start pushing candles/buds mid-March.

Without question they need a dormant period, but suspect conditions and timeframes vary depending upon location. Would not think you’ll have longterm success skipping dormancy altogether.

Here in Los Angeles, people say JBP never go fully dormant, they just sort of slow down. But that seems to be enough for a “rest period”–it gets down to high 30s for a couple months with daytime temps in the 60s. People have high success with JBP here and so I would say they don’t seem to require a strict dormant period like many other conifers.

Contrast this to what people say about douglas fir–they don’t slow down and will just grow themselves to death unless they have more of a true dormancy and colder nights. I took some cuttings from a tree at 4000 feet in the local mountains and I’m going to test this theory, but everyone says without the cold they grow like crazy and die in a few years.

Hope that helps!

Awesome, thanks for the input Keegan. I’m in the process of setting up 3 grow boxes with strict environmental controls for temp, lighting, humidity and soil moisture. The goal is to test out several variables across 4 different sample groups to determine which variables have the highest impact on health and growth rate (my day job is test engineering for a large automotive manufacturer, so this kinda fits into my profession).

Initially the experiment will be conducted with JBP over a 2-3 year time period, recording height and subjectively, quantifying the health of the trees in the different samples.

Parameters to Test:

  • Ambient vs. Controlled lighting, temp and humidity
  • Hydroponic Growth vs. Standard Watering/Fertilizing
  • Increased levels of CO2 vs. Standard Levels
  • Effects of hyperbaric conditions on growth and health utilizing CO2 instead of Oxygen

Just a little teaser of whats to come. I’ll begin a new thread when the test chambers are built and the experiment begins. Im hoping around mid to late Feb but we shall see, money being the limiting factor at the moment.

Thanks again everyone for providing your input,