Any good book on bonsai will have detailed root-pruning instructions in it. James just posted some pics and info in the FIG forum

http://forums.gardenweb.com/forums/load/fig/msg0223582815300.html?3

or you can use the search words tapla root pruning or perhaps bjs496 root pruning too. I'm not sure how much James has written yet, but he is coming on strong & gives good info.

There is a link below that may answer many questions & provide some guidance in technique, as well as the reasoning behind undertaking the effort to root prune. Along with what James has written, and his pictures, you should have a good start.

Good luck.

Al

Here is a link that might be useful: Root pruning thread

You may be missing an important issue, sure to be covered in the thread that Al linked (which I confess I didn't read, lol).

Root pruning is an extremely successful method of rejuvenating a root system, not just keeping 'the size in check'.

If plants have been allowed to become root bound, a certain amount of root pruning is essential, in my opinion. No matter what your intent is.

Thanks for the kind words and the vote of confidence, Al.

That was the first piece I wrote on root pruning. I felt compelled to write because when I first started entertaining the idea of root pruning, it scared the crap out of me. I am guessing many people think it to be a task that is somehow beyond their ability (they think they will kill their plant.) It is not. It is simple, it is easily done and it is beneficial to the overall health of the plant (as rhizo hinted to.)

This is the way I determine when it is time to pot up... If after decreasing the root mass as much as possible while still maintaining a sufficient amount to sustain the top, the root mass will not fit (with some room for growth) into the container it came out of, then it is time to pot up. You can reduce the size of the top to match a smaller root mass, but I don't. It is not my objective.

~james

Thanks for all the suggestions - I started reading a few threads, but haven't had time to read all of them. I spent a good part of the day doing more repotting - and I hope I'm approaching this the right way. Plants in our greenhouse are just starting their new growth. After reading some of your threads, I realize it may be a bit late for good root pruning. I am in a bit of a bind though - some of these plants are horribly root bound (mostly root in the pot wound around with little soil).

So please tell me if I should just wait till next year, repot without much root pruning, or what? (because of the bad timing).

Thanks - I appreciate this!

I can't imagine it being too late especailly in the case of already stressed and root bound plants already.
Please anyone else chime in if you feel I am misjudging the situation .

The biggest issue you face if you do not root prune is compaction underneath the trunk. This could lead to a girdling effect and negatively impact the flow of moisture and nutrients from the roots to the plant. Whether it will present a problem before your next opportunity to root prune, is hard to say.

If you could post some pictures, it might be easier to judge.

I agree with James here. If plants have put on a spring flush, radical root work is very iffy at best & care requirements will be critical. In addition, survival would almost certainly depend on a substantial reduction in canopy mass for trees in leaf. Regardless of root condition, I wouldn't undertake root work on deciduous material in leaf. I would take note of when buds moved this year, pot-up a size now, familiarize yourself with the root-pruning procedure this year, and get a jump on it in the weeks immediately before bud movement next spring.

Al

Well,

Darn it. I took photos today and tried to submit them to the photo gallery, but it didn't work. I have a lot of problems with compatibility with my computer - it's a Mac.

Anyway, unfortunately I can't devote any more time trying to make it work today. Needless to say, the photos showed more pot bound tropical plants. I took Taplas advice and just potted up. The roots are bad - they are girdling and are compacted, but now is not the time. Thank you very much for your advice - and I will continue to read those threads and learn how to root prune properly!

Oh boy! Forgive me for assuming that because you're in WI you would be inquiring about temperate trees. Most tropicals are best repotted in the month before their most vigorous growth - early July in your zone, perhaps late June if the trees are kept in the greenhouse during summer. There was just not enough info in your post. A list of trees you're concerned about would be helpful.

Al

Hi Tapla,
In our collection, I've been trying to repot the most obvious rootbound ones. This includes: Hoya, cycads, orange tree, rubber tree, cotton, coffee, palms, ferns, hibiscus, (and others I'm forgetting) and some fairly common houseplants (corn plant, snake plant). The problem with these plants is we want to contain their size, so they are not fertilized much, and have not been repotted regularly. Many of these plants are starting new spring growth, but many of these poor things have no root space. I've been devoting a few hours each day to their care, and have a lot more to do - so if you think I should do a more thorough root pruning - please say so!

If you contact me off forum, I'll try to give you some information that you can use to decide how to proceed.

Withholding nutrients can limit growth, but as plants cross the "critical deficiency limit" stress turns to strain and plants will go into an irreversible spiral, unless deficiencies are corrected. Being root-bound is a natural way to limit growth. A primary symptom of tight roots is lack of extension in the plant, so root-pruning/repotting is going to cause a growth surge. I need more information to determine your long range goals (if any) before I can be of additional help.

Al

I've done root pruning on hibiscus and allamanda in the spring with no trouble at all.