Yes, they do need dormancy period, something like 39dF for about a month.

Here's a previous Houzz discussion about this:

Okay. Thanks Bill.

That creates a delima, however. I got them in greenhouse environment now. If I throw them outside into the cold (usually 20 to 30 degrees F at night, but could as low as the teens), I going to risk freeze damage I know they need to slowing go dormant before they can handle hard freezes.

So what do I need to do accumulate them to the cold? How quickly do seedlings accumlate? How sensative will they be to freezing?

I do have a cold frame I can set them into.

Are they still actively growing? Are they under artificial lights?

If they aren't and have set winter buds, then they are close to dormancy. The next step would be to get them somewhere that's in the 40's to low 50's and light is diminished for a week or so. Depending how cold it gets in your cold frame that might work or an unheated garage or the like where it doesn't freeze at night?

I really don't know your climate or facilities so that makes it hard to give a solution that works for you.

I left mine out on a table all season with the first two weeks in October (40's-50'sf), then winter hit the last two weeks with 20's & 30's so Oct. 14 I put them in my cold frame that sets in the ground. It stayed in the 40's since except for a warm spell where it got up to mid 50's a couple of days. Now it's been in the low 40's so far in November.

Hi Bil,

You know your stuff. Your answer was useful. I am still learning. I have two more questions, but, first, here is some background.

I dug up ponderosa pine seedlings from my neighbors property throughout the summer and fall, and in early october I placed their small pots in a ventalated cold frame. In early november I moved them inside my home against and southern window and put a LED growth light on them.

They did not have all the same experience. The above what the average seedling experienced. Thus, now 1) some of them have winter buds, 2) some dont, 2) some of winter buds that have started to grow leaves. And, some are still recovering from being dug up.

From your reply, I got a general idea what I need to do, but I have two questions: 1) Since they are at different stages, do they need different treatment. 2) If so, what?

The only thing you can do with the ones that have started growing is keep them indoors and see if they make it through the winter and finish growing next season. Then properly harden them off next Fall. They may be okay but can't say for sure.

If you put them out in the cold now, they most surely will just die, at least the new growth will die and that will no doubt be a big set back in their development, if they make it at all through next season.

The ones with winter buds, can be hardened off over a couple of weeks and after that should be able to take the winter cold. If they're zone hardy in your area which sounds like they are from what you said.

The roots are the most sensitive part, for example, if your trees are zone 3 hardy (-40f), the roots may only be able to survive in a zone5 coldest temp (-20f) generally speaking. So figure keeping the roots a zone or two warmer. if you can insulate the pots either by sinking them in the ground and mulch around them or if the cold frame stays warm enough, that's what you'll have to do.

You can consider this a learning experience. And everything may be fine. You'll know more next spring when things start to grow again. Let us know how your survival percentages turn out. :-)

Wow. Thank you for the lesson!

What if I winter them all by keeping them at 34 to 39 degrees in low light for two months? Would that induce dormancy and keep them from dieing?

That's another avenue you could take but I don't know for sure.

Dormancy is a process, the ones that started growing will have to 'finish out' before dormancy will occur, that my take a while. Or the new growth might die and the rest of the plant might go into dormancy. Again, call it an experiment if you wish to do so.

Being the cost for them didn't amount to much (I'm assuming) you won't be out much if you try. Either way, you generally won't get 100% survival rate growing trees, if you do, it's time for a 'happy dance'. :-)

Hi Wayne, what induces winter buds? Lower temps and lower sunlight?

I started another post asking for input on a plan to pant 130 seeds to grow ponderosa pine and have trees to plant in fall 2021 and also some in spring and fall 2022 . Please give me your input at

https://www.houzz.com/discussions/6041853/critique-my-plan-to-grow-ponderosa-pine-from-seeds