Just heard about this at a nursery and was wondering if anyone ever tried it or heard of this.
Was picking up some trees and when they picked them up they just pulled them out of the ground container and all.That was when I saw that the containers were in the ground in another container that was filled on the bottom with about 1 inch of pea gravel,when I asked why they do this they told me that is how they root prune them in the spring.Pull one out of one container and put it back into another container. Some of the trees where 2 1/2" dia. in 15 gal containers.

Good Stuff Mario, I have heard of people putting them in containers then into the ground, but not with double containers.  Thanks for Posting.

Willofig,

lol thats not true root pruning and i suspect nurseries do not have fig plants long enough to give a "proper" root pruning.

I don't understand how this process actually reduces any roots in the "inner" container (the container that the tree is most immediately within).  Actually, it sounds like it doesn't.  It sounds to me as though, if you were to try using this for a long term strategy, all it would do is

• cause the tree to become very rootbound in its "inner" container, and
• have the tree effectively be living off of roots that it shoots out below that inner container (into the outer container, or the outer container plus ground), and
• give you a way to break those roots off every year by pulling the inner container out (thus ripping off or cutting off the new roots). 

p.s.  that's not to say that doing the "double pot" approach might not have other merits.  But it doesn't sound like a substitute for root pruning.

Pot in Pot


Pot in Pot Nursery Production method is getting more popular each year.

Pot in the ground, is called the Socket pot,
container the tree is in, called Production pot.
Containers are specifically made for this application.

Why;
1. Provides the grower with many of the same benefits as field growing,
but allows the tree to marketed as a container tree as opposed to burlap wrapped.
This also allows the grower to harvest trees at any time of the year, which can't
be done with field grown trees

2. Trees don't tip over in the wind

3. Root protection from heat and cold

Root pruning is handled by one or both of these methods;
Socket pot is coated with Spinout and/or
Production container is rotated 1/4-1/2 turn twice a season.

Must have good draining soil to use this system
or install drainage before setting up the Pot in Pot system.
There is considerable expense for the nursery to install/employ this method.

I have not placed my container in the ground but I have a larger planter filled with Perlite and then a 15 gallon planter pot inside that which grows my VdB in soil. I did it for drainage. It works for me. I like the idea of having it in the ground too.

Thanks for all the info on this, Hungryjack.  Since you describe method(s) for root pruning in this case, can you tell me:  what prevents the production pot from becoming root bound after a few years?  I can see plenty of advantages from what you described (for the nursery and the long-term owner).  But I don't see how you can use this technique without having to do root pruning in the production pot every few years.  (Unless you plan to leave the production pot in its socket pot always... in which case, why not just plant it inground).  What prevents the production pot from becoming root bound after a few years?  If that still happens, don't you have to remove the tree from the production pot and actually prune the roots?

Mike   central NY state, zone 5a

In this case "root pruning" means  preventing
the roots from the production pot from growing
into the socket pot and then into the ground,
which causes major damage when using this system.
I pointed out the two methods to prevent this from happening.

But as you mentioned, it does nothing for root pruning in the production pot.
This is not a long term strategy for growing,
it is used to produce trees for transplanting within a few years,
so no long term growing.
Main benefit for the wholesale grower is now they can sell/market
to the consumer and get retail for their trees,
which is accomplished by the ability to pull containerized trees from inventory,
can't always do that when you field dig trees.

For the home grower,
the only benefit I can see is for those in high heat/sun areas
and need a way to keep their containers cooler.
Again, you need well drained ground to do this with,
otherwise drainage tiles are necessary below the containers.