I've written quite a bit about the effects of over-wintering temperate trees indoors, so I'm just going to say that I would put my ingenuity to work and find a way to keep trees from freezing in more northerly zones. Setting the tree on a garage floor, then placing a box over the root mass to capture heat from the floor will keep trees safe, even in zone 5 - maybe even 4.

Whenever the temperature is above 45*, your trees are going to continue to push growth. If they are in the dark, they will push etiolated growth. Essentially, your trees at these temperatures, will ALWAYS be using more energy than they are producing. The amount of stored energy a tree has going into winter is finite, and the tree will continue to push growth, depleting its energy reserves, until the tree dies or cultural conditions are improved to the point where the tree can become a net producer of energy, rather than a net user, which in every case (user) leads to death unless the energy drain is eliminated. Even if a tree makes it through the winter, it will face spring with seriously depleted energy reserves and spend a good part of the summer 'catching up'. That lost growth potential can never be regained - it is lost forever.

Al

Thanks Al.
My plants have been dormant in the garage. I was thinking to keep them in the garage until the beginning of December above 25F and then take them inside to where it will be between 45F to 55F and will stay there until the end of February and was hoping they will stay in quiescent state and then brought back to the garage at the end of February where it wil be around freezing. May be my idea of the plant staying in quiescent state was not valid.

Hi Akram ,
what kind of temps are in your garage in January thru end of
February.
Martin

martin
On an average year it could reach as low as -23C (-10F) inside the garage in the wee hours of the mornings during January to February since it is not insulated and not heated but sharing one wall with the house. This was the temperature recorded last year on Max/Min thermometer though it was not considered as cold as a normal cold year. Even then only one out of three fig plants died, the 2nd one was severely delayed and Bifara, the 3rd one, was less delayed and it fruited even with few ripe figs, These plants were buried in maple leaves with tarp around and over them.

Thanks for jogging my memory. Coldest in my attached garage was 6F in 2008.
Martin

AL You wrote:
Setting the tree on a garage floor, then placing a box over the root mass to capture heat from the floor will keep trees safe, even in zone 5 - maybe even 4
=========================================================
I put the tree pots on piece of wood because the Garage floor is cement. Where does the Box go? Is it to cover the opening of the Pot or where?
Should I put Fiber Insulation around the pot where the roots are?

{{gwi:836559}}
no bottom
Martin

Thanks I got the Idea it is good.

First, the heat comes FROM the garage floor (geo-thermal), so you don't want to isolate the bottom of your containers from the floor, as that would insulate them from the heat source. Set your containers directly ON the floor to take advantage of both conductive and radiant heat coming through and rising from the floor.

If your tree is small enough, simply overturn a box and cover the entire tree. The open end of the box goes down - against the floor, and the top of the box is the closed end in this arrangement.

If the tree is too large or too tall to completely cover, use the box in the same fashion, but cut a slit in the box and a hole in the top (former bottom) of the box to accommodate the trunk. This usually requires you to measure the appropriate ht of the box and cut it down to that ht so it will accommodate the trunk - especially when there are multiple trunks involved. In the case of multiple trunks, you want the box to be of a ht such that the hole to accommodate the trunks is as small as possible.

If Martin's goal is to keep the roots warm, it would be better, when using that arrangement, if he set the boxes up on a shelf. It appears that the bottom of the box (unless it is open) is isolating the plants from the heat source (the floor). Cold air sinks to the floor, so the coldest spot in the garage is immediately above the floor. If the pots are insulated from the heat source, root temperatures will be colder on the floor than at any other spot in the garage. An open top doesn't trap heat from the floor, either.

The method I described not only traps heat from the floor, but it also insulates roots against extreme cold - like if you forget and leave the door open on an extremely cold day. You can try this and monitor temps - you'll be surprised at how warm it is in the box. Also, keep in mind that the slab will be much warmer near the wall common to house/garage if you need to take advantage of that fact.

Also - insulation doesn't help unless it aids you in trapping heat IN the box from some other extraneous source. In this case, it would be the floor. Insulation in the overturned box is unnecessary, though I wouldn't hesitate to use a little tape and insulation to seal the slit in the box (if req'd) and to seal the hole around the trunk.

Al

Hi ,
Those boxes you see are bottomless.
When the leaves eventually come off i just throw bed sheets on top and they will be fine. Other small plants next to boxes on floor are not cold hardy and fragile more so then some of my others and will go in attic for this particular season only.

Not seen are other small first season plants against house attached wall on other side in large boxes as well not as fragile .

Not seen are my larger plants "not protected" behind overhead door that always gets the blast of winter air when door gets opened but these are mature plants and always are unscathed each season. Even in 2008 when temps came down to 6F in garage a very cold winter for us.

Not seen are fig plants against other wall "not protected" that are several years old as well and will be fine like last season.Season before in 2008 they had bed sheet protection.
This is just what works for me and not any rule of thumb. ;)
Martin

The air temperature is due to the cycle of seasons, and 'so for the ground temperature?
Much less, the soil for its mass retains much more heat, more than three to four meters depth prevails the constant "temperature of the cave", which is, all year round, typical of each region and varies primarily with latitude and with altitude, derives mainly from the annual average temperature of the surface.

As a result every place has its own temperature of the cave, which is obviously much lower than the local temperature in summer, but warmer than the winter. This has encouraged the use of human and animal caves.
From the surface up to three meters depth the temperature varies less and less between summer and winter, until you have the constant.
This is exploited by large trees than often have roots quite at the atmospheric temperature, but to under a few feet of soil the temperature in winter is much less rigid, although there is less hot than in summer.

At greater depths, there has been a gradual increase in temperature due to heat flow from the center of the planet to the surface, the temperature increases with a specific rate increasing depth, the deeper you go, and more in hot temperature are, in-depth mines is hellishly hot, even in the north of Alaska, this calour, also if is in very small quantity, flows slowly all year, equal in every site of the planet.

Historically, the phenomenon can be exploited at Argenteuil (Paris, France) for figs in 1600-1700, with the "burial" of plants, to save the breba fruits of trees planted in the ground, outdoors.
The trees were kept low, such as bushes, the branches were bent to the ground and secured with pegs, was placed above a layer of straw and then a layer of at least two feet of soil. Under two feet of soil and straw, with calour flow from the bottom, the temperature was much higher than the surface. This was done by poor farmers, without possibily of structures. The heavy costs of the burial every year in autumn, and in spring at the disinterment, were justified by the gain obtained by fruits, unavailable otherwise in Paris, at that time.
Tapla propose to utilize this flow that,also if it is extremely little, exist.