Repotting Nursery Stock - from root bound to training pot

I am suppose to be getting ready for winter here - however the temps topped out at 73F today & forecast is 70F tomorrow. With all the warmth I started to think about spring repotting tasks for two nursery stock plants that I know are going to be a bear when it comes to repotting. A 6 gallon juni and 3 gallon mugo. Generally I have smaller stock to repot but was wondering if there are tips & tricks I need to consider when tackling these guys, especially the juni. I want to have a well thought out plan so when I start these guys they will make the transition to bonsai soil perfectly!

thanks

Randi Sharp
Richmond, VA
zone 7

Well, despite the temperatures, you have to remember that in a day's time things can change dramatically. That's why, except for emergencies, I prefer to do all my root work in late winter or early spring.

In junipers with that much root -- especially if they are rootbound -- I generally just take a pruning saw and saw from 1/3 to 1/2 off the bottom of the root ball. I pot it back into the same pot (but cut down to fit the new roots) and leave it be for the next year. I'll do some top work on the tree in early summer, and pinching etc. for the rest of the growing season.

The second year, I'll comb out the roots and then cut another 1/3 and [put it into a ceramic pot.

There undoubtedly are many ways to do this, but I and junipers have to do a careful dance around one another since my druthers lean toward deciduous stock.

I have so little experience with pines that I'll offer no advice.

Jim,
Thanks for the suggestions. The juni will be put up for the winter shortly but your suggestions offer a plan for 2010. When you reduce the rootball [the first time] and repot in the same container, which type of soil do you prefer for the repotting? Bonsai mix for back in the original, but cut down pot, or do you repot with similar very heavy organic 'potting type' soil that is the current potting medium for the juni?

thanks,
Randi

Caveat! Before sawing through the middle of your rootball, remove the soil at the top to find the nebari/ base of the tree. I have been caught out before whilst performing this operation. Some nurseries, when potting trees and shrubs, remove the pot and drop into a larger one and then fill with soil. This action done 3 or 4 times and the root flair can be below the sawing point, as i have found out!!!

Haha, nice one Will. I like a man who is prepared to announce his mistakes to the world for all to learn from.

Have you seen my "Trees lost, lessons learned"? If not, google it (in the inverted commas).

Hopefully, as time goes on, we will make fewer mistakes Kev? Feel free to use mine in your disaster area!!

As far as the Mugo is concerned, try and save as much root as possible. I start raking from the bottom up, because thats usually where most of the root is.You can probably get away with an over sized bonsai pot. Any long roots folded underneath. You can shorten them in subsequent pottings. Don't perform until the candles start to move.