Root pruning question - technique and gritty mix

briana_2006May 10, 2014

Hello All -

I have in the past root pruned fig trees that were in ~ 11 gallon plastic pots in miracle grow + peat moss + perlite. When I did the root pruning it was a bit past due but the plants came out fine.

I had read about a couple of methods of root pruning -

1) cut ~ 1/4 inch off the bottom and make a 1inch cut in 4 positions from the top to bottom i.e. cut at north, south, east, and west positions

2) remove all the dirt and then trim the roots removing roots that seem to be growing upwards or in a circular path around the base of the tree - removing I believe only about 1/3 of the overall root mass.

When I did the root pruning in the past I did method number 2 - removing all the dirt -- I have a bonsai root pick tool and once all potting mix is removed I sprayed the root mass with a bit of water from a hose to make sure all the potting mix was removed. I also lightly misted the root mass with a spray bottle of water while removing the mix and cutting the roots.

As I said before this method #2 worked well for me with the fig trees.

Questions:

1. It seems to me that although method 2 is much more work --- especially when I have done it I was a bit past due and the root mass was really overgrown -- i.e. roots growing up into the center of the root system --- that it is a better method because more of the root system is addressed and the cut off roots totally removed.

However, am I wrong? Are both methods above equally efficient for producing strong new growth in a (fig) tree?

Question #2:

I would like to soon put a tree in ~ 11 gallon or larger pot (15 or 20 gallon) containing gritty mix. I recall seeing a picture of a bonsai tree Al Tapla had in gritty mix that I believe he had just root pruned or was getting ready to root prune. It seemed like it had a good amount of the gritty mix attached to the root system.

I am just thinking forward to the time when I would have to root prune a fig that is in such a pot of gritty mix. Obviously, the gritty mix is very heavy - I will use a two wheeler to move the pot around.

Should I expect a significant amount of the gritty mix to stick to the root system when I try to remove the plant from the pot? The entire potting mix mass containing miracle grow with a small amount of peat moss and perlite mixed in is removed from the container when I root pruned before.

I am just worried that if a lot of the gritty mix adheres or is not easily removed so that it can fall back into the pot then it will be far too hard to root prune a plant of this size that is in gritty mix because of the weight of the mix - i.e. I will not be able to lift the tree out of the pot if a significant amount of the gritty mix is attached to the root system due to the weight of the gritty mix.

I currently have a number of other plants in gritty mix in much smaller pots -- I have not yet had the need to root prune any of those so I don't have any direct experience root pruning something that has been growing in the gritty mix.

Any thoughts?

Thanks,
Brian

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nil13(z21 L.A., CA (Mt. Washington))

I think technique 1 is good for correcting root issues when planting container stock in the ground. I use technique 2 when I'm putting the stock back in a container.

The gritty just falls away.

    Bookmark   May 10, 2014 at 11:46PM
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briana_2006

Thanks Nil13 for the response!
Brian

    Bookmark   May 11, 2014 at 7:11AM
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Joe1980(5)

Nil is correct, method 1 is standard for planting into the ground, and method 2 works for pots. However, what should be added to that is that when you root prune, your goal is obviously to reduce the space the roots take up, so eliminating the least useful roots is what you want to do. The larger the root, the less useful it is, being that large roots are more of an anchor, which is great in the ground, but not necessary in a pot. The small feeder roots are what you want, as they do all the work of taking in water and nutrients.

I have a rather large ficus 'alii' that I got free from a plant shop, because it was "dead". I literally grabbed it out of the rolling dump cart on its way outside. It was so root bound that the plastic pot was severely bulged, and it probably couldn't take up water, as there was hardly any soil. Long story short, it is now a beautiful tree, thriving in barkless gritty mix. What I did was grab a pruning saw, and cut out ALL roots larger than about 3/4", clipped any dead branches off, clean the old soil off the roots, fill in the gritty mix, and wait. After a few months it sprang to life, and has only improved from there.

As for upkeep, I repot it every couple of years, as needed. I basically scoop away the loose gritty mix, pull the tree from the pot, and most of the mix will easily shake away from the roots. I remove about 1/4 to 1/3 of the roots, targeting the largest ones. I usually prune out some foliage to maintain a good form too. Better for you to choose which leaves go, rather than let the plant choose. I know I said long story short, so I guess I got a bit carried away. Anywho, the gist of it is to cut out the large anchor roots each time you repot. Good luck, have fun, and enjoy the benefits of a job well done.

Joe

    Bookmark   May 15, 2014 at 9:19PM
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briana_2006

Thank you Joe for the great information!
I appreciate it!
Brian

    Bookmark   May 17, 2014 at 8:09PM
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