I have my potted trees in a garage but was contemplating insulating them just in case.  Would this be ok to use?  I work for a packaging supply company and have access to tons of this stuff.  Bubble wrap as well.  Dont know if that might be better even.  Thoughts?

http://www.uline.com/BL_855/Uline-Foam-Rolls

Styrofoam peanuts should have a much higher R rating (The higher the better insulator) than bubble wrap.  I would get a box, put in the pot and fill it with peanuts.
It might be just as easy to get a small space heater that is wired into a thermostat so it will hold a 35-40 degree temp in your garage.

There have been a couple of reports of people heavily insulating figs inside a garage or such, and the figs subsequently struggled through the following season.
See Bruce in CT's post in this thread.
http://forums.gardenweb.com/forums/load/fig/msg1009003515296.html
I don't know what the cause is, but suspect DIF, the difference between day temperature and night temperature.  Day-night temperature fluctuation is necessary for "normal" plant growth.  As I said this is just a guess - I haven't seen any information on how dormant plants would be affected.  But plants are living organisms; they react to environment.  Dormant plants "keep track" of chill hours - it isn't DIF -but it shows they are processing information while dormant.  Figs have a very short dormancy requirement.  They may be more sensitive to normal day night fluctuation as well as seasonal changes.  Something seems to be happening with heavily insulated figs and this is the only thing that makes sense to me.
Many folks in Zone 6, just bring the figs inside.  I'm in Zone 6a and haven't had a problem with temperature.  I lost a few figs when I watered heavily in late winter/early spring years ago.

Why try to keep them above freezing?  Figs can do well down to the teens, and some down to 4 F.   I know that it gets well below freezing in Tulsa, yet there are trees that live outdoors.  They survive and I know for a fact that in most years they do not freeze back at all.  '
Ox

Potted trees are more sensitive to cold than in ground trees. Working with Bonsai trees the rule of thumb is if the tree is hardy to 0°F in the ground, in a container it can only stand 10°.
So for figs the wood is hardy to 15° but if the container was left out, it can probably survive down to 25°.
pete, if the garage stays 30° and above I doubt you'll need insulation. If it gets really cold I would probably go for the shipping peanuts instead. I have used some of the shipping peanuts I got from you for my in ground trees instead of leaves. I will tell you the results.

Good luck

Bass is probably correct. When a plant is in a pot, the soil/rootball is exposed to colder temps (greater surrface area and smaller soil mass) than when it is in the ground - so you are chilling/freezing both ends of the plant. I know that bananas in pots do not fare as well in pots during the winter, as they do in ground, even if they are next to one another.

Thanks guys.

Bass, let me know if you need any more

Pete

I insulate my greenhouse in winter with bubble wrap and polytarp/vapour barrier.  I make a drop ceiling with the segregate the trees within the greenhouse with a curtain to create a smaller area to moderate.  The bubble wrap works very well, but its in a different application than you have described.
I like to avoid "foams" of any type because they are tempting for mice to burrow into.  They love that stuff, especially when it gets cold.
If my trees were in an insulated garage (with insulated door), I would simply wrap them with burlap and put them as far away from the entrance as possible.  If you are so inclined, you can add a blanket or I find that horticultural fleece (sometimes called floating covers) is terrific. I have experience with an insulated garage and the trees were fine.  Now I use a greenhouse.
Nas
zone 6a

Thank you for that info Nas.  i appreciate it

My adult trees i dont insulate but sometimes throw a old bedsheet over them to keep the cold suburb of chicago wind off them when garage door opens, this season i have 1 year olds with a tarp hanging down over them to protect them from the above breeze i mentioned. The others no bedsheet this year.
Last season the coldest my potted plants ever saw with garage temps hovering in the teens for several weeks and a week of 6 to 8 above when we had a Jan cold spell of minus 23 or so outdoors.
Plants had no damage at all this spring.

Thanks Martin.  U guys get hit with snow yet?  I enjoy your snow pictures

Pete

Hi Pete ,
we did get snow, funny thing we had several inches then at night we recieved an inch of rain which melted it , then in morning it got cold and snowed again but just a inch or so. We were that it rained as for every inch of rain equates to 10 inches of snow. Few counties away they were clobbered!
Right now as i type this its 2 above zero with an expected high of 12 today.

It has been real cold here as well Martin

Nas, Is the bubble wrap the silver type?  How wide is it?  I've been trying to find 8 feet wide, but it doesn't seem to be available any more.

Hi Fignut,

its regular packing type bubble wrap from a packaging supply place in toronto.  I bought a huge roll of if last year.  The widest you will find "off the rack" is 4 feet.  Trust me, I searched high and low, but in order to get wider than 4 feet, you need to make a custom order$$$.  I also wanted the 8 feet wide as that is very close to the height of inside wall of my greenhouse.
One thing to note is that the bubble wrap is the "big bubble" type.  The bubbles are about an inch and a half wide and half inch high.  Compared to the small (1/4 inch) bubbles that dont insulate as well.  More airspace=better insulating factor in my opinion.
Any plant 1 year or younger, probably wont be affected long term by not getting a formal dormant period its first  year.  Its safer for them to be in a cool basement or "cantena/coolroom" for their first year, especially with the rare types.  As long as its below 60 F/15C they will be fine.  And I sleep better when I hear the wind howling at my window knowing the youngins' are safe downstairs and the "adults"are in the greenhouse.
According to my family in the middle east, the fig trees never really go fully dormant.  Or if they do, no one even notices it because its so brief. The issue of dormacy is very complex and it gets even more complex when a bunch of us fig crazies are trying to grow a tropical fruit tree like ficus carica in places where it snows!
Nas

Thanks, Nas.

This might help if you are going to get a space heater.  I would replace the digital thermometer with a mercury one and that way you can work with 30-40 degree settings.  Most digital thermometers do not go below 50.
http://www.instructables.com/id/Space-heater-controlled-by-digital-thermostat/