What are the benefits to root pruning your fig tree?

So root pruning is best done when the tree is dormant, just before they begin to wake up in Spring. For Seattle, early March is a perfect time to do this.

I root pruned my 5yr old Black Madeira in march, is just one giant mass of roots. You can hardly see any soil left in he photo below.

So several problems arise when the roots get so bound up like this.

1. It literally will choke itself out and displace all of the soil.
2. It tends to dry out too quickly
3. Stunted growth
4. less fruit production

The benefits of root pruning:

Some say that any time you up pot you should also do some root pruning maintenance. Since ficus are quite vigorous it will not hurt the plant. As roots grow and become larger, they lignify and get knotted up within a pot it, which restricts the flow of water/nutrients to areas of the plant where they can be used. It also causes a lack of O2 to the roots.

The symptoms of this is the vitality of the branch extension and growth throughout the growing season. If the branch shows very little new growth during the growing season it maybe stressed from the entanglement of roots which means that it may need to be root pruned in the next dormant season.

The best time to do this is while the plant is still dormant and before it wakes up from dormancy, usually after the plant has hit it's chill requirement in early spring.

It's best to cut off a 3rd of the bottom of the roots, then loosen and trim off the thick matted roots that's left. The BM's root ball was crazy. It was so dense, that it was probably suffocating itself.

The damaged roots will send a chemical message to the plant to stimulate new root growth. These new roots will be the true work horse for nutrient up take. I also sprinkled some mycorrhizae on the roots as an added bonus.

It usually takes about a month for the plant to recover and in 4 weeks after you should see some stellar new growth. At first you'll notice that other figs will have a head start but by mid June the root pruned fig will be all caught up. So don't fret if you do not see immediate results.

Some folks will root prune every year. but It maybe better to go every 3-4 years. The best suggestion is if you have more roots than soil in the pot or if you see minimal growth,  it's time to root prune as well as up pot.

The aftermath of the root pruning.

The other benefit is that this will save you from having to continuously up pot to something larger and heavier. It's not easy carrying around 20 or 40 gallon pots around. We only have one back to use.

Update in June: 
Last year this plant added on only about 6 inches of growth. In 3 months, because of the root pruning, it has already pushed out 4x times the growth at 24 inches.