Andy,
You're welcome.

IMO, your plan sounds good, I posted my current winterization plan in another topics, but will post it here also.

The attached diagram has been modified to include the winterization plan that I'll be using this year with my in ground bushes and step over espaliers. The  scaffold branches (cordons) will be spaced approximately 2" off the ground and will be covered with Pine Shavings. This past winter all branches that were below the pine shavings survived the cold. The scaffold branches of the fig bushes will be cut back to just below the top of the mounds. Both bushes and Espaliers will be planted deep, at ~ 3' below ground surface level. In the diagram the cordons are shown in a trench below the actual ground level, this is for additional ground heat in winter. To work properly the soil has to be relatively quick draining with out high ground water.
  .

How deep are you putting the pine shavings? 6 inches is my first thought.

Chivas,
Yes, 4 to 6 inches, but it may be as much as 12 inches, since its relatively inexpensive (and re-useable) and the cost in under $6.00 for 8 cu ft bag (compressed).

For those of you who have bent trunks down to form an espalier, does it have to be new growth, or can 2-3 year old growth be bent?  Do you do it gradually, over the course of several days?  I have one that is growing straight up and I already planted it in ground a couple months ago before I came up with this plan.  Now I am wishing it were growing low to the ground.  So I can either bend it or dig up and re-plant it. 

I think that almost anything can work for insulation when covering the horizontals.  It's all a tradeoff between labor, cost, and winter protection.  Obviously 3 feet of soil would protect almost anywhere, but be way too much labor.  And just a couple inches of mulch is near worthless anywhere.  So finding that sweet spot for your particular climate/microclimate is key.

Andy, if your cold spells really are that short lived, it seems to me your climate would be ideal for this type of setup.  Certainly it's going to take at least a handful of hours for the temperature of a few inches of soil or mulch to drop 10 or 15 degrees. 

Byron, I bet that a layer of a couple inches of straw, covered by a tarp, placed on top of the mound of soil or pine shavings or whatever, would provide even more insulation from radiative cooling.

Rob,
The espalier can be started with established branches, http://figs4funforum.websitetoolbox.com/post/show_single_post?pid=1277752017&postcount=10 , but starting the tree from a cutting will provide the easiest way to maintain the desired espalier form. Good Luck.

As a reference to materials that can be used for insulation... http://www.bae.uky.edu/publications/aees/aees-13.pdf
  .
From the table 3 feet (36 inches) of Sandy Clay (15% moisture)  is equivalent to 2.31 inches of fiber glass insulation (36 x 0.0641).

Pete,

Thanks for the links.  That's good info.

Regarding insulation, it seems like 1 or 2 inches of fiberglass laid on top of the mound would provide all the insulation from cold temperatures one could want, provided the cold is coming from above.  However, it seems to me the primary means of heat loss would be coming from the sides, i.e. from the ground all around. 

So the top insulation is to protect against short term fluctuations in temperature due to variances in day/night temperatures.  But you need to get low enough underground to access the non-frozen heat-sink in order to provide long term insulation.  In other words, you need to win the month-long tug of war in January/February between the relatively warm deep dirt temperatures and very cold temperatures of surface dirt.  Seems to me you actually want some thermal conductivity for that purpose, at least from the bottom. 

Rob,
Extending the insulation 1 - 2 feet past the cordons (Wing Insulation) is all that is needed in most locations to use the thermal mass of the soil for frost protection. The principle of Shallow Insulated foundations is explained in this document, http://www.cs.arizona.edu/people/jcropper/desguide.pdf
The cordon is treated like "the frost proofed area under an unheated slab"
  .
By placing 4" of waterproofed fiberglass insulation on the ground with a width of 3' to 4' (1-1/2' to 2' on either side of the cordon) you will essentially have created a mound of "Sandy Clay (15% moisture)" that's 5 feet tall and 3 to 4 feet wide.

This is great stuff to plan winter protection!

Can leaf compost be used with or in lieu of wood chips to increase insulation value and to actually provide a source of heat as the compost decomposes?

Pino,
All insulative material needs to be dry or it will cause rot, also heat and moisture from composting may damage the fig trees.

Thanks Pete!

What about dry soil 3 mix type?  I am trying to get away from anything that will be attractive to mice and the like.

Pino,
I haven't tried "dry soil 3 mix type", but Ive used the Wood Shavings, Fiberglass and Extruded Foam (Pink and Blue board) with good results for protection. I plan on using wood shavings, but haven't formulated a plan as yet for rodent proofing.

Thanks Pete Your plan sounds like it should work! 

Rodent control is a challenge.  I don't know of any one panacea.  Need to get them from all angles.  (preventive measures,  bait, traps, timing ..).  I hate to use bait since it tends to spread and pets and other wildlife can get into it.

Pete - thanks for the thoughts and link to the ground thermal insulation method.  Very interesting!    A few years ago I posted some information about the solar geothermal greenhouse design that I saw.   It was amazing and I still think about it, hoping to have one someday.    The insulation in the ground was absolutely essential for the success of that system and the document you posted really helps.

  So for the community garden, I may need to consider some insulation or put a pretty large heap of mulch on top and spread far?  

 I also appreciated the additional thoughts about rodent control.   It is essential.   Many of us have had rodent issues in our garages, storage sheds, etc.   I remember one posting that Bass made many years ago when rodents destroyed some of his stored plants.  That is a surprise none of us wants to encounter.   

Byron (Ingevald)

Pete,

That's great stuff, thanks.  Is there a quick answer to how to waterproof the insulation, so I don't have to read the 54 page document?  Is a tarp on top sufficient, or will water wick up from below? 

Has anyone considered training double trunks to provide a little more insurance against the unpredictable winter weather? 

There would be 2 main trunks and 4 horizontal branches similar to Pete's diagram. 

To maintain the desired separation for air and sun penetration shoots can be thinned as required or optionally once you know for sure that the branch has survived without winter damage (late June) you can then cut 2 of the 4 branches be left with the standard espalier but with 2 trunks rather than 1.

  

Pino,

Not a bad idea.  You could actually keep double horizontals, and alternate verticals as well.  That way if you lost one from each side, you'd still be OK and could maybe train a new vertical be a horizontal.  Although it's likely that any climate-related situation that would take out one of the horizontals would also take out the other. 

Byron,
You're welcome.
Thanks for posting the links in that topic about the Geothermal Greenhouse, I've actually implemented several of the projects in the attached links.
Leaves and shavings are actually cellulose, they are not as dense as cellulose insulation but they have worked for many people. The "pile" just has to be kept relatively dry to retain its insulative value.  For my fig bushes a circular cage of fence material filled with leaves or shavings and covered loosely with a tarp, 12 linear feet of fencing will almost form a 4' diameter circle and its all reuseable. Even Snow fencing could be used to form the desired "fenced area" and then filled in with mounded insulating material, it could then be covered loosely with a tarp. Again the only problem would be to provide some form of rodent protection and ensure drainage of water
BTW I had 12 stored trees last winter that had severe rodent damage, they were already killed by the cold, so I have to take some blame ; )


Rob,
The insulation, whatever is used has to be protected from the weather, usually its a tarp and or tar paper, but a simple box, cold frame, hoop house or any of the other posted methods will work.


Pino,
Your describe 4 cordon espalier is patented and was posted in a topic by Harvey C. , http://figs4funforum.websitetoolbox.com/post?id=6769908 It was developed in warmer zones due to the longer growing season, from the linked literature it seems to have been based on the Japanese espaliers.

Pete,
Patented a 4 cordon espalier fig training system? ..LOL
When you think of it is just one of the many "best practices" in growing figs.  How can someone claim to own that?  Hopefully it doesn't apply north of the border.

Rob, you said "likely that any climate-related situation that would take out one of the horizontals would also take out the other."
It may be that 1 horizontal has more residual winter (or other) damage and can tolerate less.  In that case you luck out if you have the extra arm.                

Pino,
In the linked discussion on the patent, I posted Ken Love's description of the fig espalier procedure that had been practiced in Japan for decades.
It bears mentioning here because it gives an over view of the procedure and does mention a 4 cordon espalier...

Thanks for the link Pete!  I like this training for figs.  I need to read it carefully.

One thing I don't fully understand is the pruning of the verticals.  I understand you want to space them every 1 foot or 2 feet, or whatever you choose.  Then you let them grow for the year.  Then you cut most of it off.  But in all of the Japanese photos they have these mostly horizontal branches sticking out from the main horizontals.  Is that because each year you need to leave a little bit of the current growth vertical so that the vertical has somewhere to sprout the next year?  Or some other reason?  Anybody know?  Does my question make sense?

Rob,
If you look at page # 14 and #15 of the PDF document linked in post #19 there are diagrams that show that the verticals which are spaced 8" apart (on alternate sides of the horizontal) are trained to be 4" to 6" off the main horizontal before they are trained vertical, this is to create 2 rows on alternating sides above the cordon with enough space for vegetative growth. On page #15 which is the 1st year for pruning the verticals, the vertical pruning detail is instructing to "prune back to an outward facing bud , while leaving 2 -3 buds off the horizontal cordon". And yes, the stubs are caused by the yearly pruning.

Thanks Pete, somehow I missed/forgot you are growing the cordons below ground level for added protection. I can't wait to see how yours do, I will be starting my planting in the spring.

Rob, Your question makes perfect sense. I spent a good deal of time last winter trying to figure out what was being done from the photos in the links posted by Byron and Pete. I'm betting that like training grapes, you won't really understand it until you do it for a few years.
You have the gist of it as far as I understand it. If you look at the diagram pete posted, the spurs are trained vertically, while the Japanese photos seem to show the spurs being trained more horizontally. Each year the verticals (would they be called canes?) are grown from the spurs and then cut back to one or two nodes of the current seasons growth after going dormant. In this way the spurs get one or two nodes longer each year.
I assume that at some point the cordons or spurs may need to be renewed. I hope I get to the point where I have to figure that out. The post about the Kadota espalier eludes to this some what, but doesn't really give specifics if I remember correctly. One would hope that it would be easy to do with figs.

Anyone have any idea the trunk caliper size of a fully mature fig tree?  It would make sense to ensure you have enough height of your horizontals to accomadate a full mature size horizontal trunk(s).

I'm reading people considering training their horizontals at 6" for the height of the surrounding soil.  Is this high enough when dealing with a fully mature trunk size?

Also, regarding the waterproof insulation idea, was their a product in mind that would be optimal for this?  I found a product called Insul-tarp which seems like it might do the trick...

smithmal

Malcolm,
In NYC I haven't see any fig tree with a trunk caliper greater than 8". In cold zones the main trunk should not get large enough to be a major concern. If you follow the prescribe espalier dimensions, the main cordon is @ 16" from the ground with enough clearance between verticals 8", 12" and 16" for future growth. As mentioned by Aphahn in the previous post " you won't really understand it until you do". I now realize that the prescribed dimensions are given for specific reasons... http://figs4funforum.websitetoolbox.com/post/show_single_post?pid=1281309326&postcount=37 


BTW, in my case I will be looking to test "Earth Coupling" the main trunk (with coarse sand) for added winter protection. That's one reason to keep the main horizontal as low as possible. If the caliper of the horizontal becomes too large, removing the soil below the cordon would be an option.