I would pot them up now. I always repot or plant anything I buy from a nursery as soon as possible....even in July.

Avoid repotting deciduous tees when they are in leaf unless it's an extreme emergency. The best time in your zone is in spring immediately before buds move. Pot-up now, into a similar (to what it's in now) soil and do your repot in spring of 2010. That will also give you time to reconsider using the 1:1:1 Bark: Turface: Grit mix, even though the 5:1:1 mix is still a much better choice than most bagged soils. ;o)

Al

Take,

In zone 7 repotting in Fall is a good idea.

I agree that it's not ideal to repot a fully leafed out plant. If your plants are badly rootbound it's probably worth it to pot them up and do a bit of freeing up of the roots. If they are not so bad I'd wait until fall and repot when the leaves start falling. In my part of Z7 there is 8-10 weeks or so of soil temps where roots will grow after they have been pruned. Also Fall pruning gives a bit more insulation to the roots when If you're anywhere near a Northeast US WholeFoods Market the 'Organic Mechanics' mix they sell is a pretty good media as is and does not use peat at all.

Here is a link that might be useful: repot fall or spring?

Everyone, thank you for your suggestions!

Herman, thanks for the link - very interesting. I think I will wait and repot them in the Fall. It looks like some people are having really good results with this method.

From an energy management perspective:
Whether or not it is advisable to prune roots in fall depends on whether or not the plant will be over-wintered at below freezing temperatures. If the tree is kept under cover and from freezing, it is fine to repot in fall. If it is to be kept in the ground, or will be subject to freezing temperatures, it's best to wait until spring.

Roots are not all equally hardy. Fine rootage is less cold tolerant than partially lignified roots and MUCH less cold tolerant than fully lignified roots. Repotting in spring before budswell guarantees that the fine rootage will not be killed as a result of freezing, whereas trees potted in fall run the risk of having to lay out energy to grow roots, only to have them freeze and die, in which case the tree has to lay out double the energy to regrow the roots in spring.

I'm not sure I understood this: "Also Fall pruning gives a bit more insulation to the roots when Why would fall pruning insulate roots at less than 15*?

Al

Al,

"If it is to be kept in the ground, or will be subject to freezing temperatures, it's best to wait until spring". Did that come out of your text book? LOL you make plenty of pronouncements. Don't you agree its good practice to provide some credible citation when dispensing 'facts'?

re 15F. Above 15F the roots will be ok on their own with or w/o insulation provided the cold period is not extended. Below 15F the roots will benefit from the added insulation.
Those details are based on my experience in Z7 and agree pretty much with what Whitcomb says in his container culture text.

In zone7 Fall there is plenty of time for roots to get a start on re-establishing if the pruning occurs on time. The discussion would have more credibility if replies were tempered with relevant experience.

I would go ahead and repot your maples now, as long as the new growth has hardened off. If the new growth is still tender, wait until it hardens off. I have successfully repotted containerized Japanese maples throughout the year and have never lost a tree. Although fall, winter and early spring may be ideal, containerized plants are much better able to withstand the shock of transplanting than B&B trees.

A few tips. Try to repot on a cloudy cool day if possible. Avoid disturbing the root ball as much as possible unless the tree is root bound, in which case you should gently separate the roots on the outside. Use good quality potting soil that drains well and a container large enough to give the tree room to grown, but not too much bigger. Water immediately after repotting but do not fertilize. Keep your trees in a shady location for at least a week and water as needed. Mulching around the tree will help it retain moisture better.

"I lecture regularly by invitation" LOL ..the lack of an invitation isn't going to stop you!

My point is that relevant experience is crucial. If you had experience growing Acers in Z7, using a few different approaches, I would feel your points had traction.

We learn best not from dogma but rather from sharing relevant experience and insights.

I usually find that those resorting to personal attacks have little to contribute that is positive. There is nothing dogmatic about me - I'm always most interested in learning new things and adopting them into my methods. I'm also unsure how you can discount long and substantial experience rearing a wide variety of deciduous and coniferous trees in containers only one zone removed from yours and TaP's, saying it is irrelevant, but ..... whatever.

Interesting that the text you quoted so thoroughly refutes your offerings. I can't understand why someone would intentionally jeopardize the well-being of their trees and advise others to do the same. It's better to be safe than sorry - trees only die once. Experience means nothing if we gain that experience doing something dogmatically, clinging to 'facts' that are erroneous. I think the forum is capable of deciding whose offerings ring true, so we'll leave it at that.

Dawgie - there is a distinct difference between repotting and potting-up. TaP was asking about a procedure during which the plant would be bare-rooted and the soil changed. It would be inappropriate to undertake this type of extensive work while the tree is in leaf. Repotting (again - not to be confused with potting-up) out of season is a good way to lose a tree.

Al

I really appreciate everyone's suggestions on this topic. I think you guys (Al and Herman) both have very valid points.

Herman has had good results repotting in the Fall for z7, so although it may be unconventional, it works.

But for someone with not much experience like me, I think I will go with Al's suggestion to be safe and pot-up now. I moved to Memphis recently so I'm not sure how cold it can get here.

I have two Sango Kakus and I may try both method and see how they turn out.

Again, I appreciate that everyone took the time to offer their advice and knowledge. I've been learning a lot from reading this forum.

Al, thanks or clearing up the terminology. Re-potting is not a good idea to do now for most people and most plants.
Potting up can be done almost anytime here.
I built an automatic misting system under lath on the northeast side of my house. Part of it has bottom heat for cuttings. I can get away with a lot using it.

Here is a link that might be useful: Pictures of my garden

I just repotted a 1 gallon Boskoop Glory into a 2 gallon. The leaves were not looking quite right and upon inspection of the root ball I found lots of places where the soil had washed out leaving small pockets where pillbugs had taken up residence.
So that was a problem. I screened me some oak leaf mold and added a little potting soil and bark to make my new soil mix. The repotting was successful and the plant looks better. Beautiful cultivar is Boskoop Glory.

takeaphoto,

I live an hour and a half from you and have several hundred JMs. I repot them whenever I feel like it and never have a problem. I use a good organic mix with Myco fungi and keep them in a cool, shady spot for a week or two after potting up. My grandmother used to say you can re-pot anything at any time if you give it enough water and shade, and I've found this to be true. I've repotted in winter, spring, fall and even in the scorching dog-days of August with excellent results - but my preferred time to re-pot is spring. This gives the tree all season to stretch the roots out into the new soil and have them mature before winter. Then they're all settled in for a long winter's nap! Just don't fertilize JMs when you re-pot. You don't want any new growth in late summer, as it won't harden off properly before freezing weather hits (had to learn this the hard way). Wait a year and then use slow release organic ferts (to prevent nitrogen burn) in early spring.

Regards,

K4

Perhaps you're treating the roots gingerly and "potting-up" w/o problems while the trees are in leaf, but if you're truly doing a repot, including proper root-pruning, I sincerely doubt there are no difficulties.

Al

For the most part I'm potting up, as you describe it, but I've gotten in plenty of stock during the summer that had been bare-rooted for shipment that was in full leaf when I got it. They did just fine being "repotted". Again, good soil, water and shade seems to work for me. In fact I just repotted one today in full leaf that I had to carry on the plane with me 1/2 way across the country. I'm not worried about it surviving.

In my garden, potted maples are a temporary evil as I prepare the raised beds for my collection. I have every intention to put them all in the ground. About 1/2 way there.

K4

K4