Has anyone had success with planting two individual trees to same hole(distance 1 feet from each other)?
Is it true that by restricting the roots of a fig ,it can grow better as being demonstrated in nature with figs growing through opening in walls and streets?

I'm not sure about any benefit to the trees. But I have planted several varieties as you describe. Pruning the roots so that I can get the trunks as close together as I can. The reason that I have done this is because I have (unplanned) ended up with 2 or 3 trees of the same variety. Since yard space is limited, I put the like varieties in the same hole to make a multi-trunk planting. The trees (Alma, LSU Purple, Imp Celeste) are all doing well.


CliffH

If space is limited, I'd think that grafting different varieties that you like on to one tree is a better solution.  You get to taste different figs without planting all of them in the same place.

Haven't done it with figs, but it is widely practiced with stone fruits and apples. I wouldn't expect any negative affects. Issues in stone fruits are difference in vigor of the trees and trees with very different chill requirements which may cause one to shade out the other.

I have seen a picture of such a tree somewhere in this forum.  One can always prune them to size...The same can be said for planting several fig trees in the same hole.  Those less vigorous tree will be crowded out by the more vigorous ones. 

For other fruit trees I have also done this a couple of times to plant cross-pollinators together.

Hi,
I do it often because I use root-suckers to create new trees. I'm never sure if those will root or die.
So I plant two in a spot.
Fig trees like to grow bushy, and that's not a problem to have two together.
I'm always using the same strain in one spot, so both have the same vigor.

Root constraining is good to dwarf the trees. They seem to have a higher productivity too.
I use 80Liters (20 gallons) trashcans with bottom removed and that protects the root from the raids of the damn rodents (moles, voles, you name it; it is here raiding the garden) .
Only drawback I've seen is the watering. In case of a dry month the trees can't go fetch water out of the trashcan and I had some get stunted from lack of water when I was away on holidays.
So now I make small holes on the sides of the trashcans (they are more cracks than holes in fact ) and hope for the rodents to not find the holes. I put those holes deeper so hopefully the rodents won't find them.
Rodents are more active in the first foot (30cm of depth) of the ground.

Funny, I got rid of two trees that were in the trashcans (replaced them - wrong strains). The bigger roots were in the first 30cm/1' and then only hairy roots.
The trashcans are 80cm (2.66' ) high. Funny the roots did not escape the container. In the last foot (30 cm) were really just hair like roots.
I had expected to find some tap roots down the trashcan and into the clay dirt.
I had expected the clay to be broken from the roots ... I had to use a hammer and a crowbar and break some more myself ...

I’ve done it with a number of trees, both with four and three together, with more or less success. They do great overall. With stone fruit like peaches and some plums, they will start dying off after ten to fifteen years here, until all have to be replaced. Not an easy task with mature stumps.

If you want hundreds of figs ripening all at once to preserve then this wouldn’t work for you but if you want a great variety of figs ripening in sequence over a long season and your space is limited, it can’t be beat.

Below is a planting of a group of three figs together I planted last year in a triangle around 18” apart. Bushy, short Ronde de Bordeaux is on the south point of the triangle with Lebanese Red on the back left and Marseilles Black VS on the back right. A four planting wouldn’t work well for figs because the front ones would shade the back trees but a three planting gives each fig its “day in the sun” adequate to ripen figs well. Figs can be trained to grow out/up rather than up with a space in the middle of the planting to allow for air circulation. The only thing I can't train is my gardners, who will quickly gird a tree with their weed eaters if there aren't plastic protecters on the tree trunks.