I don't have all the specifics, since I'm not the one who does our growing, but we have our seedlings under heat and light from March-June, with high humidity and regular watering. I've noticed that this year we've had much more overcast (in Michigan) than usual and our seedlings are a few weeks behind in growth. BUT, all that to say, our Hemlock typically reach 8 inches in the first year, and I'm skeptical of the info you've seen that touts one inch only..

Mine were outside in pots before the temps got into the 60's regularly, I'd bring them in at night in case of freezing but I though a tree that grows in zone 4 could take cool temps.

Could be I made them go dormant like what happened to some of my other seedlings with this cold weather this spring. I can leave them for a while but with so little growth, there must be something wrong.

I wonder if seedlings that have gone dormant need a cold period before they start growing again?

BTW: The info came from the USDA:

Look down under seedling development. At least I know not to believe it anymore. :-)

Upped the watering and tried to remember to mist frequently during the day. That seemed to improve the seedlings a little but nothing more than the tips of new needles started showing at the center bud.

Then I went camping, watered and put the tray under my deck, to keep the sun off it, so it wouldn't dry out. Evidently it was more moist under there or something because after a few days a couple of the seedlings started growing again. One remarkably.

I should've done it sooner but I recently put the tray inside a 'tent' to raise humidity 24/7, so we'll see if that helps any. Learning process any time you try something new. :-)

I should have another month of growing season left. Right now, I'd be happy with an inch of new growth before fall. :-o

After 3 weeks in the tent, I noticed a little progress.

We had near a week of humid weather with clouds and occasional misty rain, so I removed the tent so they could be exposed to these conditions.

I have 10 pots left that appear to be living and green but only a few showing significant growth.

All 10 have at least a few to several tiny green needles, guessing 1/32" long protruding from various parts of the center 'bud' that formed earlier this season. I'm almost sure they went dormant bc of our long cold spring and had to 'break bud' to start growing again.

Live & learn.

I am thinking that being these have some new growth, albeit small and are green and alive, it's possible for them to go dormant and start up again next spring. So I'll try to over winter them. I may be wrong but it isn't over until it's over. :^)

The three with significant growth are still growing, very slowly but including the stem length, I think I've surpassed the USDA information linked above, eluding to 1" of growth in their first year. ;-)

This one started pushing late but started none the less. (note the 'bud' that broke, between the original spring growth and the growth that started later in the season.

This one was sort of late but started coming on better once inside the tent. It even has two little 'branches'.

And the best of them all with over a quarter of an inch of new growth after it broke bud without going through a first winter. :-)

Now to see if they'll harden off properly and can I get them through a z3 winter. :)

Maybe it'd be best to put them in an unheated garage/room the first yr.........

I wish I had a spot that I knew would stay in the 40's all winter and I could check on them during that time.

My garage may get way too cold by December and my basement may not get cool enough by the time these need to be dormant. Every winter here is different.

There's a cold frame, in the ground outside but it hasn't been tested for plants yet, especially very tiny ones. And once out there, they're most likely inaccessible for the winter.

I just don't know if they'll stay moist enough, unattended, over that long of a time.

Any ideas?

At least your garage would protect from the most extreme temps & desiccating winds.

Good point beng. :-)

My biggest concern in the garage, is that the roots/pots will be subject to the below 0 temps for possibly weeks on end, usually through January. So even in a box with mulch insulation, it's possible it could get too cold, idk.

One possible option is, an insulated area down my basement. At this point, it's staying 5d(f) cooler than the basement and that differential may increase once cold affects the cement walls of the basement. So I could keep the seedlings in the garage until the insulated area stays <50d, then move them from the garage, eliminating exposure to the worst of winter.

Thirdly, I have some potted cuttings and a few seedlings I plan to put out in the cold frame later this fall. So I could put them in the cold frame, cover everything inside with mulch, foam board the door and a pile mulch on top. Might be the best option?

My 'cold box' under the bench. Gets mid to upper 50's in the basement during the cold part of winter, depending on.

I sure will look into and read this Brandon. I saved a copy of Vol6 Ch4 in case it disappears from the web before my imminent long winter, affords me ample time to read up on things. 8^)

I'm sure it was my ignorance and lack of proper facilities, coupled with a colder/longer than normal spring that caused the seeds low success rates. But before I was presented the opportunity to get seeds off this historic tree, I wasn't even thinking of growing Tsuga from seed.

In fact, I may have been better off getting cuttings instead, if I wanted get a true clone of this 100+ yo tree.

The knowledge and experience gained is priceless, I only wish I could've had more success this time around, considering the provenance of this tree. And I'm sure I could get more seeds if I wanted.

In the end, if I get just one surviving tree, I would feel like this attempt was a booming success. :-)

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I decided to use my cold frame to overwinter all my potted conifers, including the Tsuga seedlings. It's out of the wind, it will be warmer than the garage bc of being up against the house and in the ground, plus I can bury the immediate area in mulch (in case there's a lack of snow).

All my seed pots stayed nice and moist in there all winter without any intervention.

I just can't think of any place more well suited for the job, period.

JFWIW:

My 'Cold Box' under the work bench (pictured above) has finally reached a low of 52 f. Not what I had hoped for and occurring a little late at that. If mid 40's, I might've considered moving some plants there to spend the rest of the winter. The basement temp in general has been hanging pretty close to 62f and it's been fairly cold outside the last few weeks so it's been a good test for the possibility of using it for cold storage but I think will fall a little short.

Everything I'm wintering this season ended up outside in the cold frame. Supposed to snow half a foot Friday into Saturday. So far, one inch of snow for the season.

In the attached unheated garage, my small thuja seedlings spend weeks and sometimes months being frozen soild in their shallow trays at minimum temps of -8 to -10 C / 14 to 18 F. I am confident that tsuga and all other hardies would fare equally as well. Of course, depending on the weather, prolonged above freezing temps also occurr in my garage and that's when I need to be more alert to any trays needing watering.

I have a ' attached unheated garage ' too but mine is an outside 'shell' and not finished at all inside. So without a ceiling and vented soffits on two sides, it's almost like having an open shed. The wind can blow through north to south and vice versa. Couple that with a colder climate (z3), I know for sure it has been a least -20f, the times I've checked and possibly colder. It all lends itself to (freeze) drying conditions so I've ruled out my garage for winter storage of plants.

OTOH: My cold frame is below ground, against the house foundation, protected against any wind and somewhat insulated. I have no idea how cold it can get in there but previous observations tell me that it'll stay above the severe below zero temps yet stay cold enough so not to worry about mold or breaking dormancy. And things seem to stay nicely moist down there. But this is the first time keeping live conifers in there so I'll/we'll know more by the end of March. Stay tuned. :-)

Okay, for sure then your garage is out of the question. Your next to the foundation, below ground insulated box should work well and will definitely keep the seedlings from experiencing the extreme cold, especially if you receive a good bit of snow as further insulation. Hopefully, mold won't be a problem if temps in there do remain above freezing.

Bill, my region had been bumped up to zone 4, though last winter we experienced -40 F and slightly below in what was the coldest February in something like 60 years.

Thanks!

Winter shouldn't be a problem for mold here, last year, things stayed pretty froze on into March. And once things freeze under the insulated ground, they'll stay cold for a while. And by that time, things could be moved into the garage as we're generally past the sub zero stuff by then.

I can almost see zone 4 from here, I'm only a couple miles from the line but last winter, we had plenty of -20's to -30's sub zero nights in Jan/Feb with -40's f a couple of nights and 3 days of wind, gusting >50mph, blew all night. Don't know if it was a record but colder than I can remember in say 35-40 years.

Just to close this one out. I used the cold frame to store all my seedlings and rooted cuttings for the winter, SEE THIS THREAD:

Out of the 8 Hemlocks from seeds, there looks to be about 4 that will grow again this year. A couple that I discarded had a small bit of green in side the winter buds but weren't breaking bud and I figured they just didn't have enough energy to make a come back.

Here're the ones (4) that are breaking bud and I expect good things for them this season. :-)

This one made the most growth last year but is the last to break bud this year (two buds).

Second best:

Third: (first to break bud).

And the last:

They'll be under the lights for now and watered regularly.

Update:

Stunted little things as they are, they've put more growth on already this season than they did all last season. These were seeds from the MN state champion tree in Brainerd MN. Glad to see I might get a least a few going. :-) (pictures in same order as previous post March 10)