Stumbled across a giant unknown bush/tree on a public trail today. I decided to take a few specimens to experiment on and practice. One of them is a tall sucker that I pulled up with a good amount of roots. It is 5 ft tall from roots to tip! It had no leaves except 2 baby ones on the very tip.
I wasn't going to be home for a few hrs so I wrapped the roots in a wet paper towel to keep moist.

I just put it in a 5 gallon bucket with promix. It is a little over 1 ft buried and 4 ft sticking out.
Was this the right thing to do? or should I chop it down some? No pictures at the moment.

you can cut it, or wait for the die back, usually nature does the pruning, you ought to put it in a semishade area until it has more roots.   it should grow well for you.

Hi erics11,
It depends on what you want to do :
Do you want to keep it in the pot ?
Or more general, do you want to keep that tree small, or not ?
If you want to keep the tree under control, cut it at 2 or 3 feet over the dirt.
When to do it ? I wouldn't do it now. I would do it in March or April next year.
For now, keep the pot moist in a shadowy spot for two weeks and then the tree should be fine and you would apply the same cares as for a normal tree .

By the way, are you sure that this tree is of a good strain ?

Eric,
you don't have to cut, unless you want shorter tree. As long as it has roots, it will keep growing for you, I did the same thing with the Capri I pulled from the mother tree nearby. It, not only, survived but it has figs on it now...here's a link to it, 
Capri Fig from Glendale Church Parking Lot you can see for yourself :)
Good luck.

I have had poor luck doing this unless the tree is tented with plastic to keep the humidity high. Keep the plastic off the tree with stakes and tight against the container. Remove the plastic every few days for some air-flow. Water lightly once per week. Keep like this in a shady spot for a 3weeks or until you see more top growth, whichever is longer.

Thanks for the replies. My plan is to keep it in a container. Not sure what variety it is. I saw it a long time ago and it didnt have any fruit so i left it alone. This time around it is loaded with figs, but they are all small and unripe. I have plenty of space to fill so its more of an experiment. Ill check on the mother tree periodically to try to ID it when they ripen. For now ill just keep this one in the pot in my warm garage for a bit and then transition it outside.

Picture of mother tree. 20 ft tall

It doesn't matter how tall but it does matter if there are enough roots to supply the leaves with water. Start in the shade.  If the leaves don't droop you're good to go.  If they do pull some off.  If they don't droop in the shade you can progressively move in to more sun.

this might even be a Capri Fig... we'll see....