Yes they are alive with no frost Damage.
Coldest night to date:4F outside on Jan 24,not counting the 25 miles per hour north wind.
My protected plants are 4 years or younger ,old.
The protection is:
:Framed 5/8: Plywood boxes filled with dry leaves.
So far so good,works well.
I have under there:
Kathleen Black
Malta Black
Atreano
Aubique Petite
Maltese Falcon
Paradiso Bronze
LSU Gold
Tacoma Violett,and others.
Here is the pixes:
Note: the old plants are not protected.
They are:
Hardy Chicago
Marseilles vs Black
Note :Snow is about 1 foot tall

Note Tipycal Box size:4footx4foot by 2 foot high.
Of course I trim my plants,(to be covered) to 2 foot tall in Dec.

Good for you Herman.
Pretty soon (in a dozen of weeks) the plants too will come out of dormancy.
You mentioned "4F on Jan 24", do you mean inside the box?
That day was really cold and it was -22F in Ottawa so it must have been cold in NJ too, colder than 4F.

Hi Herman.  That is great news.  Thanks for sharing.

It is amazing what can be achieved with some creative planning.

We have had a tough winter here so far too, with lows in the lower 20s regularly and even down to the lower teens some nights.  That is unusually cold for North Georgia Zone 7b.

All of our trees are in-ground but heavily mulched, and even if they get cut back to the ground by the cold (which the new ones almost always do), they always come back from the roots, until they get big enough to over-winter better.

The older well-established trees still look great.  I checked them today.  The Georgia Yellow Unknown Hybrid; the LSU Purple; and the Hardy Chicago have not been damaged at all.

Given your tougher climate though Herman, the boxes for protection are a great idea and now sound like a proven winner, protecting down to near zero.

I will be pruning tomorrow, because Spring will be here before you know it.

It got up to about 60 today I think.

Best wishes to all.

John
North Georgia Piedmont
Zone 7b

Ottawan, if there is no heat source wouldn't the temp be the same in the box as outside?  That same night it was 5F here in NY,  No covers on my plants, will see soon enough how everything did.

Ed to answer your question no.
I have a fig shed that I put my figs in I insulated it with fiberglass on the walls and a thin ceiling aluminum type material. I have a remote thermometer in there and it is always 9 degrees warmer inside than outside. Now with the real cold of winter here I have put an electric heater inside on a thermostat and the room maintains 34-38 degrees no matter how cold it is outside. I think alot of freeze damage done to young unprotected plants is more from dehydration than actual freeze damage. They can take the freeze but the wind and cold combinded with lack of water due to dormancy = freeze damaged young tips.

The difference is so much that all soil at bottom of box,around the tree is soft and not frozen,That mean inside The insulated box is 32+F.
It makes sense why:When warmer outside in the middle of day,the insulation inside(leaves),get warm,and ,later in the night it retain the warmth till next day when it start the process again.
Note:I had pixes from begining but they were lost ,so I fixed it now,the pixes can be seen.
What is nice about my boxes,is that every box is kept toghether by ,only 8 pieces of 2 inches wood screws,2 screws for every corner,so it can be taken apart very easy in Spring and installed it again next winter.

Of course the top panell is not screwd in it is  sitting there stable and secure by it's own weight,and can be removed if too hot outside ,or for other reason later early in the Spring.

Hi Ed.  Hope you are well my friend.

I'm no expert, but my understanding is that it works like insulation: The box traps air (not perfectly but far more than an open space) and the trapped layer of air helps to insulate the plant from temperature extremes occuring outside the box in the day/night cycle.

For example, it may get up to 30 during the day and down to 5 at the coldest part of the night, but the temperature inside the box drops slower, meaning that the figs inside are exposed to both lesser extremes in temperatures and lesser periods of time at the lowest temperatures.

It's not going to make a dramatic difference, but there is a difference in plant stress between 5 degrees for 12 hours and 15 degrees for 6 hours.

But if it stayed 5 degrees steady with no warm up in the day at all for an extended time period, it would get down to 5 degrees in the box too in time.

This sort of insulation box helps to moderate the extremes, but only slows down the cooling (or heating).  That's how mulch works too.

Our figs are mulched at the base, but no other protection.  Hope your figs are fine, and those Latturalas are really tough!  The one you sent us grew like a weed this summer and still looks pretty much untouched by the cold here.  Our Texas Blue got toasted pretty quick, but the more cold hardy varieties seem fine so far.

Very best wishes.

John

ejp
Don't forget the geothermal heat from the ground inside the box that is trapped inside and helps keep the temperature a bit warmer than outside. That is why it is better to make a box with wider base than the top to cover more ground area to trap more geothermal heat. Mulching (or other covering) outside around the periphery of the box helps further by reducing the trapped heat loss near the periphery of the box.

Does anyone have a picture of what a frost damaged branch or tip looks like?

i don't have a picture.

but for mine, on the north side of my house ... bascially, everything turns a dead brown color, and gets a slight wrinkle to it and the terminal bud is no longer green

a green terminal bud is typically a solid indicator of "i'm alive"

Yes, I was thinkng about the geothermal heat as well Ott. In fact if you had good enough drainage where you are, you could dig down a little and set potted trees just below the soil line before boxing them in. This should give you better contact with the warmer ground.

It might also be helpful to keep in mind that decomposing organic material gives off heat. So the leaves in the box are likely providing more than just insulation. A fresh deep layer of mulch just before covering for the winter may provide additional 'organic warmth' .

Thanks Jason, I think that helps a lot. The other day before we got another big storm and the temp was in single digits I was out looking at my uncovered trees. The one in the middle of the side house had all green buds at the tips of the branches. The other tree is planted at the very edge of the house before it would almost be out in the open and most of the bud tips were shiveled and brown. I'm am wondering now if that isn't a good location.

Okay, I wasn't going to go there, but since we are talking about geo-thermal, some high nitrogen organic matter (i.e., manure) buried under a cold-frame will also produce heat.

Personally, I'm not that desperate for heat!  ;-)

Best wishes to all.

John

To Otawan:New Jersey is not Otawa in coldness,so I am sure it was not any colder than 4F,outside,in a sheltered place,not in the open wind.

To Kathy: If you was succesfull to root 88 cuttings out of 91,then you have a secret ,better way of rooting cuttings.
If you do,please make a new post,titled something,like :
My rooting method,and explain,it and I bet a lot of people will be helped.
Unless you use the rooting in the bag method, wich was allready explained here.
Rooting in the bag does not work for everyone,and I am one of those..

I have an old fashioned Min/Max thermometer (of the mercury U-tube kind)

Hi George:Thanks for posting your reading.
They are very close to mine,no doubt.
Last winter  my reading was 14*F,for the coldest night in Jan,so very close to your readings for last year.
This is a colder winter no doubt compared to 2010,but so far no super low extremes cold yet.
We will see if it will go any lower,on negative teritory ,the rest of Winter.
My lowest reading here was -4F,in 2000,or 1999,I am not sure wich one,but I am sure of the reading.
Extreme low here in Willingboro:
-10*F,on 11th of February 1938.

Thanks Kathy:Your Specter of variety choice is an average one ,it has hard to root and easy to root cultivars,so Congratulation again.
You are doing a great Job.
Personally I am more willing now to get as good as you are,at my rooting endeavor,seeing your excellent results.

Honestly I never been better than 50/percent succesfull.
Best Regards

Geothermal Heat is most likely the answer.  There is a cattle watering device that works on this principle.  The water trough sits over a hole dug four feet into the ground, and ground heat rising keeps the tank above it from freezing. 

We have roughly the same result with our covered figs.  Heat coming up from the ground keeps the interior of our covering devices warmer than the outside air. Since no wind can take the heat away, and insulating leaves (or straw, or mats, or whatever) slows down heat loss from the container our figs stay warmer than those exposed.  If snow piles up around the containers they stay even warmer.  I don't get a lot of snow, so I pile dirt up on the sides of the barrels I use.

One nice big container is a garage.  Mine stays just above freezing even in the coldest weather because I have a small thermostatically controlled heater out there.

Absolutely nooo damage here either Herman, we haven't gotten as harsh winter here, just returned not long and all inground is fine. You certainly got much more snow, but that is insulator. Coldest been here this year - 8. Covered figs fine.

Hi Herman,
I am wondering how old are your plants that you have covered in the plywood boxes?
Thanks

Grant
Z5b

What I was wondering is, are you keeping your all your 4 year old and younger plants, even 1 year old plants, outside under the plywood?
Thanks

Grant

Z5b