How much sun do pines need during winter dormancy?

[Bonsai Noodles]

I'm sure this varies by species, but what have your experiences been with keeping pines in winter dormancy with/without sunlight? Let's say popular pine species for now: Japanese Black Pine, Japanese White Pine, Scots Pine, Mugo Pine, etc. I'm planning to keep a Scots Pine in an unheated/unlit garage, but would it be wise to get a grow light if that's the case?

Seems like Brent from Evergreen Gardenworks say evergreens to fine in a garage: https://www.evergreengardenworks.com/overwint.htm

But I've seen others like Ryan Neil from Mirai begging to differ.

Your thoughts?

 

[HorseloverFat]

Oh my goodness! I can‘t wait!

I’ve heard so many theories...

 

[Fred1991]

Michael hagedorn writes about this subject with a lot of scientific merit in his book “bonsai heresy”. It’s a very good read

 

[Bonsai Noodles]

Oh my goodness! I can‘t wait!
View attachment 343004
I’ve heard so many theories...

Yeah! Seems like there's been so much discussion online, but I can't seem to find a definitive answer. Maybe an updated thread with people's experiences can shed some light on this never-ending debate...

Michael hagedorn writes about this subject with a lot of scientific merit in his book “bonsai heresy”. It’s a very good read

I'll see if I can pick up a copy some time! Sounds really useful.

 

[HorseloverFat]

Michael hagedorn writes about this subject with a lot of scientific merit in his book “bonsai heresy”. It’s a very good read

Second that! One of my favorite horticultural reads.

 

[vp999]

Some one please shed some sun in this topic....

 

[Dav4]

I believe that where winter temps are consistently in the mid 30’s F or colder, the pines, regardless of species, are metabolically so slow as to not require any light... think alpine evergreens under 10 feet of snow. I’ve personally kept jbp, jrp, and shimpaku in a garage with one north facing window for upwards of 4 months every winter, frozen on the concrete floor. For over a decade, they went in at thanksgiving and went out around April first and never skipped a beat. This was in MA over a decade when we still had consistently cold winters and I could keep them frozen. I’d say all bets are off if the temps hover at or over 40 F for more then a few days, though. Down here in tropical 7b N GA, those same trees stay on my benches all winter except for during the coldest week or two, soaking up whatever sun hits my backyard this time of year.

 

[MaciekA]

Michael hagedorn writes about this subject with a lot of scientific merit in his book “bonsai heresy”. It’s a very good read

I've been at Michael's garden several times this year as a seasonal student and have spoken to him about this topic in person, and one interesting thing he talks about with respect to dormancy is that it isn't always a binary on/off switch, there's a spectrum of activity. For example, Michael doesn't believe that Japanese Black Pine goes "fully" dormant (quote) "in our climate" (aka Portland metro). In his garden, his JBPs continue to visibly (or measurably) expand various types of mass (including roots) right through the winter. Perhaps not enough to fully awaken and start opening their buds, but enough to keep moving and benefit from light. This is very similar to some things Ryan has said on the topic regarding dormancy being somewhat spectral in nature (see also his comments on summer dormancy). Ryan and Michael's gardens are separated by only ~32mi and maybe a couple hundred feet of elevation, so perhaps they're both observing similar behavior across their conifers.

But I've seen others like Ryan Neil from Mirai begging to differ.

Your thoughts?

I think nobody fully in the wrong here and there are different answers for different climates. Trees will survive dormancy in a garage in Minnesota, but maybe those same trees would benefit from sitting out in the sun in Oregon, even if we may get some sub-freezing temperatures.

 

[Paradox]

Ive kept pines in a dark garage with nothing but one window ten feet or more away from the benches they were on or in a mostly covered cold frame against the north side of my house (ie not in the sun) every winter for 9 years. None have died because of lack of light. Some people have had them buried under snow for most of the winter and not die from lack of light.

 

[cmeg1]

Various forestry service cold store pine seedlings in dark.....cold temps are good.....freezing is best...I forgot specific temps in my article.I read it to store mine in a fridge(cuttings). Believe it was 35 or below with best results with freeze.

 

[Fred1991]

I've been at Michael's garden several times this year as a seasonal student and have spoken to him about this topic in person, and one interesting thing he talks about with respect to dormancy is that it isn't always a binary on/off switch, there's a spectrum of activity. For example, Michael doesn't believe that Japanese Black Pine goes "fully" dormant (quote) "in our climate" (aka Portland metro). In his garden, his JBPs continue to visibly (or measurably) expand various types of mass (including roots) right through the winter. Perhaps not enough to fully awaken and start opening their buds, but enough to keep moving and benefit from light. This is very similar to some things Ryan has said on the topic regarding dormancy being somewhat spectral in nature (see also his comments on summer dormancy). Ryan and Michael's gardens are separated by only ~32mi and maybe a couple hundred feet of elevation, so perhaps they're both observing similar behavior across their conifers.



I think nobody fully in the wrong here and there are different answers for different climates. Trees will survive dormancy in a garage in Minnesota, but maybe those same trees would benefit from sitting out in the sun in Oregon, even if we may get some sub-freezing temperatures.

Ah man I wish I could do that! Im sure you learn a lot. Little off topic - do you work on his tree? Or do you get help on you own?

 

[Japonicus]

I've kept all my conifers including BP WP mugo hinoki and junipers + others
under my sunroom on the N side of the house. The Sun arcs across the S side, so no light really, no UV index value but fresh air.
This year I may keep a few out on the ground, but the ones that I move under shelter mostly from the wind
will wait for mid teens to be forecasted regularly (late Dec - early Jan) here.
Still on my bench 7' above ground, with overnight lows in low 20s Fº now and then,
or at freezing every night for the last week, high at freezing tomorrow with wind
so hinoki will get some wind shelter till that passes. Other than that nothing yet.

 

[Shogun610]

I burried all deciduous and pine , both native and non native in the ground with mulch up to /around rim of the pot. I also built a frame and draped a frost sheet over the garden bed they’re healed in. The sheet with a pallet used as a wall offers shelter from wind, along with the frost cover ... shelter from frost and wind. Might reinforce with more wall protection.. but it suffices. I’m in 6 B... so it may be in teens for a few nights.. might cover them up with more mulch by then

 

[0soyoung]

3.14159265359 lux.

 

[MaciekA]

Ah man I wish I could do that! Im sure you learn a lot. Little off topic - do you work on his tree? Or do you get help on you own?

I can't speak for other students, but for me the first year sessions were all on the material in the garden, covering a broad set of techniques on a broad set of species. Off the top of my head, in hands-on, on-site I have covered: JWP, JBP, japanese maple, junipers (of various kinds), ezo spruce, mountain hemlock, nootka cypress, lodgepole pine, scots pine, chojubai quince, wisteria, japanese snowbell, and possibly a few others I'm forgetting.

In terms of my own material: I've been given long-term "homework" in the form of a project related to itoigawa cuttings, and I've also brought in 3 rather large field-grown pines (2 JBPs and a scots pine, still pretty recently out of the ground). For the material I brought in, the work was mostly just mid-term planning and a small bit of development adjustment. I'll be bringing them in again over the next year for some minor nudges.

Michael and his apprentice(s) are able to taylor a learning path for a diverse set of goals and starting points, it's a really great way to learn.

 

[Bonsai Nut]

Well... small pines in the mountains seem to do just fine buried under several feet of snow. Just sayin'...

 

[Michaelb]

Why bury your trees? They can't heat themselfs like humans do?
Mulch will be frozen and i think the underlaying trees will be too.

So only indoors will make a difference..

Or am i wrong? Pleace correct me if i'm wrong.
I find this an interesting subject.

 

[AlainK]

If you take a walk in tha mountains and see majestic trees, don't even ask yourself if they were kept in a garage.

Of course potted trees need a little more care, for instance adding mulch up to the first branch if you live in a very cold area like Minnesota, but they're not "indoor bonsai"... Not only "mulch" will isolate the roots to a certain extent, but when it ferments, it gives a little heat.

Where I live, the climate is warmer and warmer every year, but I've got a place where I dug a rectangular spot, 15-20 cm deep. I puts a layer of Zelkova leaves, my most fragile trees, then add some more leaves up to the 15-20 cm.

Well, I used to : now, "deep freeze" (here, -5°C to -10°C) is exceptional and doesn't last for more than 2 or 3 days...

You'll be safe in Belgium, pines will even be safer than in the Alps.

BTW, my friends from Brussels sent me this very funny video from the RTBF (in French) :

https://fb.watch/2f1aVsfN6K/

Joyeux Nouillel !

 

[Japonicus]

Bjorn in Nashville. A couple days in the teens Fº in February, remainder around freezing.

as for

So only indoors will make a difference..

Yes indoors makes a fatal difference if you're talking indoors as in your home.
I do not consider an unheated garage, loop house or shed indoors. It's outdoor shelter.

Placing a tree on the ground is often times sufficient as the ground temp is 3 degrees or so higher
than the actual air temp. Bjorn does that with some of the trees in the above video.
Up North where snows remain most of the Winter and buries the trees
it is a most helpful insulator and provides moisture when needed. Natural wind break as well.

 

[PA_Penjing]

clearly, storing a pine in the dark won't kill it or even hurt it noticeably. It's been argued they take off a faster and stronger in the spring when given sunlight throughout the winter. It doesn't seem hard to believe to me. Do what works best for you, 'cause you aint gettin' a black and white answer anyway. I leave my trees on the bench to 27ish degrees, below that they get set directly on the ground til about 15 degrees then they spend the night in my garage, but my garage is well lit and a little to warm to utilize full time because of southern exposure and a south facing window. I'm talking about Amur maple, spruces, pines, junipers, DR and burning bush. Obviously my candy ass trees are treated as such