Most hobby gardeners know that fruit plants productivity increases as the plant matures with age but not many gardener knows exactly which part of the plant plays major role in this productivity increase with maturity, though intuition and experience point to the plant root system. If that is the case then it leads to my main question related to a dilemma.
The dilemma for the potted figs is if I don’t prune the roots enough, I may have to prune roots soon again; and if I prune roots too much then it may adversely affect the production in the next growing season.

I have read a number of posts about root pruning; some suggesting cutting off one-third of the root ball and others have pruned off one-half of the roots.  My question is then ‘how much pruning off is too much that will reduce fruit production in the next fruiting season’. What will be the optimum root pruning off that gives enough time between next root pruning but minimum effect on the next year production.

It's a good question and my container figs are now getting mature that soon I will need to do extensive root pruning also.  I'll be interested to hear what others say.

Hi OttawanZ5,

In 2012 after my own big kill, I sew away,following September, a rooted trunk to make a new tree. The trunk had an height of 1,5 meter . Root mass was two hands full not more as I didn't want to kill nor stunt the remaining trunks.
The new tree produced 6 brebas the next year - which considering what the tree had suffered, was not bad .
Generally when I tare apart one trunk, the new tree does not produce the next year.
But, that tree did not bear a main crop the same year (in 2013) - but remember that I'm in Zone7.
This year, the tree produced both brebas and main crop figs.
So for such a tree leaving a volume of 4 liters/ one gallon should be enough.

Another remark from this experience: for me, the trunk seems to hold resources as well.

I have two large whiskey barrel pots that must be root pruned this year.  From asking around, the consensus is to take a few inches off each side (kind of squaring it off) and the bottom.  I've also been told to remove any thick roots that I see.  This is the tutorial from Bill's Figs in NJ. Caring of Fig Trees.

Akram,

Your question is difficult to answer since the root growth varies so much from one tree to the next.  I bare-rooted and root pruned hundreds of trees when I lived in Houston.  Some need root pruning as frequently as every 2 years, while others will go 4-5 years and be okay.  In some cases the roots will outgrow the containers before the top does.  In general this is my method.

• Bare root the tree.  I have several reasons for doing this.  First, it is hard to know what to remove if you can't see it.  Second, as the roots grow, the growing mix and roots begin to compress.  If the compression is not relieved, the roots will deform causing poor performance and eventually choke off the top of the tree.
• Remove any deformed or damaged roots.
• Remove a handful of the thick anchoring roots.  The thinner roots are more efficient at taking up moisture/nutrients so I want to leave as much room for them as possible.
• Trim the length of the remaining roots.  The roots should be short enough to lay straight in the container with about an inch or two from the edge.
• Repot.
• Repeat.  Pay attention to the tree. If the growth is slowing down and/or the limbs are growing thinly, it is time to root-prune.

I've always heard 1/3, and I've always erred on the low side.  I have yet to root prune a fig, though.  Half seems like too much.

Thanks James for the very detailed and helpful explanation with pics.

Thanks for sharing your method, James.

Any roots circling around a pot are useless.  That's the main rule.  So there should never be any roots that are longer/taller than the pot, as James suggests.  Only reason to cut any more than that is if they clump up when you are putting the tree back into the pot.  Imagine this jellyfish shaped thing.  It's hard to get it into a pot and keep the roots spread out as they should be.  You put the tree in, dump mix in, then you have to kinda pull up on the tree and shake it a bit so that the mix goes below and fills in the spots.  But this process is imperfect and often results in either compressed roots or air pockets below, or both.  So that's why you might want to cut it back a bit more.  In James' photo, most of the roots he has left have enough girth that they are not going to just flop around when you put in the potting mix, they are going to more or less keep their shape.  If he left on those long stringy things, they would end up compressed together, which is not what you want. 

An alternative to a full root prune is a partial one, where you may leave some of the mix on the interior part of the rootball, but you'll cut off the outer edge all around and at the bottom, and pull out and get rid of anything that is winding in/out and around.  This may be faster/easier and may shock the plant less.  But probably a full root prune is required at some point.  Just not necessarily every time. 

I am hoping that by using fabric pots I will end up doing less root pruning.  Time will tell how much root circling still happens.  Even if circling is completely prevented, there is still the issue of compression, but that can be alleviated by just cutting some chunks out of the thing with a sawzall or hole saw and/or putting in a bigger pot. 

Thank you James Rob and all for the good input.
Spring is the only time for me for root-pruning so it will be a race between pruning with canopy adjustment) and time; & time means to finish as many as possible before full leafing out.

Pruning routine can become one of the major factors for eventual decision to downsize the inventory to the most likable productive plants in ones collection. Age is another one for me (& eventually for many others sooner or later). Gone will be the days to get hand on any variety that becomes available.