Overwintering Help Please: New In MT From OC CA

[Firstflush]

I mentioned moving to MT and now I have. From OC. Got rid of all the trops.

I kept a JPM, Chines Elm (Jacqueline Hillier) and 2 Liquidambars. The liquids I don’t think can grow here without significant protectiom.

My trees were allowed to get the first frost and the steady diving temps until they went into a unheated greenhouse. We have gotten into the teens at night and it will get minus F a few times this winter. Elm is in a deep 4” and JPM is in a 1 gal.

The soil is getting more frozen if not fully. Should I keep the trees in the unheated greenhouse…elm and JPM.
I brought them inside out of fear. Bad move? Put them back?

BTW the wild RMJs, J. Horizontalis, ponderosa pines and larch are off the hook here.

 

[Firstflush]

Thinking quickly on getting them back outside. Worried somewhat on breaking the safety of dormancy.
It will be there first real winter after CA. My move was in Feb this year. They got freezing temps in a trailer for 3 days, that’s it.

 

[Deep Sea Diver]

Complicated situation. Technically your trees are likely in Paradormancy now, not full dormancy. It is also one of the two times the trees sustain the most winter damage… the other is in late winter early spring.

Our rule is once the trees go in the greenhouse or cold frame, the trees stay there. If the temperature goes up after this point we just open the door (a fan is always on in the greenhouses).

Just as a comparison, we put all our more sensitive trees in the greenhouse last week. Yesterday all the small developing trees went in the ground in the back garden. The other trees are going in either the cold frame or dug in under the trees today.

If you wish to learn about wintering over with examples of storage download the resource here. It’s written with azaleas as a focus, being a borderline species, but actually pertains to all trees.

Best of Luck!

cheers
DSD sends

 

[Firstflush]

Thx. I ran them back out to green house.
Hoping for the best.

 

[Dav4]

The goal with overwintering is to keep your trees cold enough to maintain dormancy while protecting them- and their roots, in particular- from extreme cold. They can sit in frozen soil all winter as long as those two goals are met. Fwiw, there are many threads here on overwintering that you can review. Also, a long time member from that part of the world- @Dan W. - may be able to give you some pointers.

 

[Deep Sea Diver]

Good point. Burying in ground can be an effective wintering over technique.

Then the issue is less about roots and much more about cultivar age/cold hardiness, wind, sun and varmint exposure. These factors often yield branch loss, trunk split and sometimes loss esp if the media isn’t kept wet before/after freezes.

All three plants are zone five cold hardiness in the ground, so as OP mentioned, definitely on the edge in the warmer areas of Montana, even in the ground as the top hamper will likely take a beating if nothing else.

Not sure how cold it gets in the greenhouse. This will protect the trees from the wind. Yet if there are subzero exposures, more measures would be needed.

One thing one could do to improve the chances… if electricity is able to be run into the greenhouse. That’s to put in a milk house heater activated by a thermocube. (see Amazon Thermo-cube). This is what we use for edgy tree…. This rig has worked amazingly well for us over the past three years.

cheers
DSD sends

​

 

[Colorado]

I’d be surprised if any of those species survive a Montana winter in an unheated greenhouse, but who knows. I think you need temperature control.

Better yet, just focus on those ponderosas, RMJ, etc that you mentioned instead

 

[Dan W.]

I also would add some type of heat to your cold frame if possible. I use small electric greenhouse heaters. One would be plenty for a small cold frame. The option mentioned above sounds great too.
Personally I would attempt to keep your cold frame between 32 and 38 Fahrenheit. It will occasionally get warmer than that during nice days and colder on the sub-0 nights but the swings won't be as extreme. The biggest thing to mitigate is how often they freeze and thaw. Freezing isn't bad, but a constant freeze/thaw cycle is what you need to avoid. Really hardy/native trees can remain frozen all winter without any issues, but I don't think I'd risk it with those species you mentioned in zone3 or 4. I'm 4b in WY by the way.

Here's the heater I use. It looks like they come in 1500W or 3000W

 

[Deep Sea Diver]

Nice heater! Like that IP4 rating.

Best
DSD sends

 

[Firstflush]

Have a single room heater we have used in the small greenhouse for veggie seed starts. Gets warm however. Maybe I’ll try the basement the basement but zero light. Maybe high 30s low 40s in there.

 

[Dav4]

Have a single room heater we have used in the small greenhouse for veggie seed starts. Gets warm however. Maybe I’ll try the basement the basement but zero light. Maybe high 30s low 40s in there.

Too warm

 

[Deep Sea Diver]

Hmm…. have to agree to disagree with @Dav4 on this point,

High 30’s low 40’s works well as long as the temperatures are mostly on the lower end. The trees can successfully accumulate their chilling hour requirements in this zone.

Our greenhouses stay at these temperature ranges most of the winter. The trees haven’t broke dormancy in the past two years. Here’s one of the GH’s 24/7 records.



The thermocube mentioned previously will help to lower the temps, by shutting the heater off and on at intervals to keep the temps down.

Best
DSD sends

 

[Dav4]

Hmm…. have to agree to disagree with @Dav4 on this point,

High 30’s low 40’s works well as long as the temperatures are mostly on the lower end. The trees can successfully accumulate their chilling hour requirements in this zone.

Our greenhouses stay at these temperature ranges most of the winter. The trees haven’t broke dormancy in the past two years. Here’s one of the GH’s 24/7 records.

View attachment 515596

The thermocube mentioned previously will help to lower the temps, by shutting the heater off and on at intervals to keep the temps down.

Best
DSD sends

I guess I wasn’t clear enough, but I’m less concerned about chilling requirements being met and more concerned about premature growth starting in mid winter. I had it happen once keeping a palmatum in the unheated and drafty basement of a 200+ year old house in zone 6 MA. I moved it into the basement in late November- temperature near the walk out were in the upper 30s when I checked-but buds were swelling on it before New Year’s. The chilling requirements were apparently met by early winter but the lack of consistent cold allowed the tree to start growing way too early.

 

[Deep Sea Diver]

Thank you that’s a very good example.

Just for other folks reading in. Buds can break once a tree accumulates their specific chilling hour requirement… even though wintry weather hasn’t finished.

We regularly have had our landscape flowering cherries bud early in January and last year again in February, only to have full bud break/leaf out in mid March. (Has occurred earlier and earlier in the past 15 years.)

It’s these events followed by return to frigid temps when trees often sustain the most branch damage.

The sudden fall freezes before full dormancy also inflict a lot of damage.

Cheers
DSD sends

 

[pandacular]

@Deep Sea Diver I have the same brand of thermostat/humidor. Any tips on keeping it dry and accurate out on my benches?

 

[Deep Sea Diver]

@Deep Sea Diver I have the same brand of thermostat/humidor. Any tips on keeping it dry and accurate out on my benches?

Here’s a thought:

- Get small plastic or better still wood box, turned upside down. Say 6x6x6

- Drill 3/8 holes in the lower sides for airflow. -Secure sensor in the ’ bottom’ of the box, with a spacer between box and sensor… (Secure with something that is easy to remove like straps to screw eyes.

-Spray paint box white.

- Position on bench so bottom is at least partially open… then secure box… (straps/screw eyes to bench)

Cheers
DSD sends

 

[pandacular]

My initial attempts including plastic containers yielded some less than stellar results (as did trying to dump the sensor in the cinder blocks under my bench, to no one’s surprise), but I think this may work well.

In the next few weeks, I’ll also be finalizing my winterizing plans and will certainly make a post about it.

Thankfully, the cold snap seems to have broken leaving me some precious time to recover from an illness.

 

[Deep Sea Diver]

Good to hear you are recovering.

Wood is the best way to go… think sort of like the boxes used for meteorology sensing equipment. So a simple Stevenson screen equipment box with holes vs the louvers to avoid water intrusion.

cheers
DSD sends