Repot young Japanese Maples

jeezitsMay 18, 2011

I just purchased 6 Japanese maples and was hoping someone could give me some advice on how to handle them. They are all young and look healthy, around 20-36" inches in size, and are fully leafed out. They came in #1 pots in a mix of Sphagnum peat, perlite, and gel cubes to hold moisture. There is also some composted material in the mix and some topsoil. I mixed up a batch of 1-1-1 gritty mix earlier this week. From what I've read here on the forums, I believe it is too late to do a full repot with root pruning.

What is my best course of action to handle these young trees? Is it too late to carefully wash away or separate the existing medium from the roots, untangle them, and pot them up in my gritty mix?

If it is too late, would I be better off moving the existing root balls into larger pots and surrounding with gritty mix?

I appreciate the input. I don't want to make a fatal mistake and kill these trees the day after I received them.


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peapod13(8 South Sound WA)

As I understand it, Japanese Maples aren't very tolerant of messing with the roots while the tree is in leaf. So I'm not sure I'd try a repot (with root pruning) this year. Also, the difference between the soil porosity of the 1-1-1 gritty mix and just about any other media out there is so different if you tried to pot up using the 1-1-1 gritty mix, you'd likely run into trouble with one soil being too dry and the other being two wet.

If you plan to keep the trees in containers, I think you probably have two choices this year.
1) "Plant" the pots in your yard for this year. Basically creating a raised bed using the pots. For this to work, you'll need to make sure the soils in your yard are well draining (ie not clay) and that the pot has several medium sized holes in the bottom so water can drain into the earth.
2) Plant up into a 2 gallon pot using a soil with similar characteristics and a wick, being carefull with the roots.

I think either of these methods would work for this year (in fact both methods have been recommended in the past). These are both temporary measures and you'd need to repot (with root pruning next year)(if you plan to keep the trees in containers).

Maybe some of the other guys will jump in later with more information for you.

Good Luck


    Bookmark   May 18, 2011 at 6:29PM
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Thanks for the response Blake. Can you (or anyone willing) explain to me the science in how it would affect a tree in leaf to carefully wash the soil from it's root ball and spread the roots out in the gritty mix? I've been trying to piece the information together from various sources but I haven't quite figured it out. If someone could enlighten me and/or point me toward some good introductory sources on root systems I'd appreciate it.



    Bookmark   May 18, 2011 at 8:55PM
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peapod13(8 South Sound WA)

Unfortunately, I can't explain the science. I've been waiting on my local library to get a copy of Dr. Alex Shigo's "A New Tree Biology..." transferred from a different library.

My guess would be that due to the thin bark and reasonably large surface area of leaves in most of the Japanese Maples, there is a large amount of transpiration. The tree needs the roots to replace the amount of water lost in transpiration. When we bare root trees, even without a root prune, the tiny little hair roots that actually are involved in the process of absorbing water from the soil are damaged. The damage to these extremely important roots doesn't allow the tree to replace water as quickly as it's lost through transpiration. End result the leaves wilt and the tree begins to drop leaves to balance the amount of water absorbed by the roots with the amount of water lost through transpiration.

It may also have something to do with the interchange of specific hormones (sorry their names escape me at the moment) between the shoots and the roots.


    Bookmark   May 18, 2011 at 9:41PM
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jeezits - I have a similar situation, only with just one JM, not 6. I posted a question in tapla's (Al's) "trees in containers" thread but haven't received a response yet.

I plan to keep my JM in a container because the soil here is clay and alkaline plus we have too much winter sun and wind. I, too, was hoping to use the Gritty Mix to pot up the tree but everyone seems to recommend against bare rooting JMs (or most trees, for that matter) after they have broken dormancy, so it looks as if this will have to wait until early spring of next year. Sigh.

Anyway, my tree is coming via mail order and won't be sent in a pot. Is there any "best" potting soil that can be used for Japanese Maples until we can get them into the Gritty Mix, or, as suggested by you, Blake, do we just try to find something that looks like the soil already around the root ball and hope that this will allow the tree to maintain?


    Bookmark   May 19, 2011 at 2:30PM
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peapod13(8 South Sound WA)

I'll always defer to Al's excellent wisdom. (He's the one primarily responsible for any knowledge I have at this point.)

I believe he' s provided as much help as possible for the time being.

Once your tree actually comes in, I'd advise posting a pic or two, and I'm sure Al will follow up with advice.

Congratulations on your new tree, and good luck.


    Bookmark   May 19, 2011 at 10:37PM
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Hi Blake - Al did respond to my post in the "Trees In Containers" thread and basically said the same thing - I need to wait until I get the tree to find out whether or not it was sent bare root, how far out of dormancy it is, etc. I will take pictures of it when I get it and post them in that thread for advice, as opposed to doing more hijacking of jeezits' thread. (Sorry, jeezits.)


    Bookmark   May 19, 2011 at 11:39PM
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peapod13(8 South Sound WA)

Holly and Chris,

I certainly understand your enthusiasm. Not long ago I too was asking for guidance on timing of repot, amount of root pruning and limb pruning on 5 of my own maples. I bought three of my trees during the winter and the other two during early bud swell. So I was able to get all 5 trees into the gritty mix.

I hope nothing I've said curves either of your enthusiasms.

With Chris's trees, the 5-1-1 is probably close enough to the soil the trees are currently in, that he'll be okay to "Pot Up" with the 5-1-1 mix. I.E. pull the tree, root ball, soil and all out of the #1 pots and plant them root ball intact or mostly intact into #2 pots with the 5-1-1 mix making up the difference in size between the current root ball and the #2 pot. Using this method, a wick will help determine moisture levels in the pot and help with any perched water table that may form at the interaction between the current soils and the 5-1-1 mix.

With Holly's trees, until the actual condition of the tree and roots/root ball (if any) are known, it's hard to proscribe anything further.

Once again, I wish you both the best of luck with your trees.

Please feel free to post pictures, updates etc in a thread I've started called "A Journal for Following the Development of Containerized Maples". My main goal for that thread is to provide a place for me to follow the development of my own trees, but it is my desire to also have others share there experiences with growing their trees.

Of course, Al also has a thread called "Trees in Containers" where you may recieve a quicker reply to questions and certainly information from a very deep well of personal experience.


    Bookmark   May 20, 2011 at 2:24AM
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Holly, no problem on the thread hijack... we're all working toward the same goal here :) Now that I've gone back and read every message in Al's "Trees in Containers" threads, I realize I probably should have posted there in the first place.

Blake, thanks for all your help. I appreciate the advice, and what you've suggested seems to be consistent with everything else I've read.

That being said, I'm in a better position than Holly to experiment, give that I have 6 (soon to be 9) trees to nurture (or torture). Like Holly, I received these recently via mail order.

I purchased the young trees recently because I have a 7' Sango Kaku that I believe is infected with Pseudomonas. I decided that, in the event I end up watching my tree suffer a slow death, I'll comfort myself by taking care of some younger Acers that may one day earn the job of replacing my Sango Kaku.

Since I've ordered the trees, I have come to realize that there is a lot more to caring for them than I originally anticipated. There is an amazing amount of helpful information in this forum alone. I appreciate all the time everyone here has spent building such a large wealth of information, and hope to someday contribute some useful experiences of my own. As my brain is always in sponge mode, I've been trying to understand more and more about tree growth, container gardening, soils, etc.

In the interest of furthering that understanding, I decided to select a candidate (victim) to move into the gritty mix. I'll likely be moving the rest into the 5-1-1 mix or something similar as was suggested. I am, however, a visual learner, so I decided the best way to learn my lesson was to subject one of these poor young trees to what I'll describe as a partial "repot".

About 24 hours ago I moved the Trompenburg into a larger pot with gritty mix and a wick. I took it out of its current pot, and carefully removed around 75% of the soil from the root ball by repeatedly dunking it in a bucket of water and poking it away with a small screwdriver.

The roots had done a pretty good job of filling up the original container. I didn't prune them, nor did I mess with them much other than to untangle them a bit. My hope was that by minimizing any damage to them, I might make this "repot" a bit more successful. I watered thoroughly then poured on another gallon of water that had some Mycorrhizae and superthrive mixed in.

My plan is to root prune and do a full repot next year if the tree survives this ordeal. I plan on observing it and hopefully learning from this experience. I consider it a training exercise to prepare for the disaster scenario where I may some day be forced to repot a tree that is in leaf.

Please let me know if you think there is something I should have done differently (given my fabricated disaster scenario).

I've included some pictures below of the 6 trees: Trompenburg, Sister Ghost, Seiru, Olsen's Frosted Strawberry, Kogane Sakae, Japanese Sunrise. These were taken just a few minutes ago. Most of the trees are still stretching out after their exciting adventure with the fine men and women of the US postal service.

Thanks again for all your help.


    Bookmark   May 20, 2011 at 10:34AM
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No curbed enthusiasm here, Blake! I am going to be patient with this tree as I want it to survive and thrive. I have killed almost all of the JM's I've put in the ground because of the "anti-JM" conditions we have here in Colorado. This will be my first venture into trying to grow a tree in a container and I want it to be successful - mostly for for the sake of my tree but also for my rather slim wallet!

I will see what shape the tree is in - root and leaf-wise - when it arrives and go from there; hopefully I can at least put it in the 5:1:1 mix this spring without disturbing the root ball a great deal. I can certainly wait until next spring to transplant it into the gritty mix - first I need to get it to survive the winter!

Chris - Very pretty trees, and definitely all leafed out. Good luck with your experiment. I am sure you had your 'guinea-pig' Trompenburg sign a consent form before you began the experiment. :-D I hope the tree does well for you and that you will update us on its eventual recovery and survival - or its decline, should that be the result. I can't afford to experiment so I will be a bit more gentle with my 'victim,' but look forward to learning from your experience.


    Bookmark   May 20, 2011 at 12:36PM
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jojosplants(9/ Tucson, Az.)

Those are some beautiful tree's ! May I ask where you got them from?

I looked at the site you ordered from and they are some really nice tree's.

I'm thinking one would be a nice gift for my mom. She's always complaining how Arizona doesn't have the color changes she used to see in Ohio. :)

I've seen yours in other threads. Also very beautiful tree's! Nice work with the repots!

Best wishes to you all!

    Bookmark   May 20, 2011 at 10:39PM
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JoJo - Davidsan's Japanese Maples has some wonderful cultivars, many of them quite rare (and priced accordingly!) but all of them are unusual, compared to the ones you see in most nurseries, and for the most part they are reasonably priced. I bet your Mom would love getting one, or one from wherever Chris got his - though I don't know how a JM will do in the heat of Arizona! (I guess I am thinking of places like Phoenix; I know I wouldn't do well in the heat there.)

I'm from New England originally so I, too, miss all of the beautiful fall colours - there are very few hardwoods here in Colorado so we mostly only get yellows and golds in the fall. Being able to grow a Japanese Maple or six would make me very happy! And many of them have differences in colour spring, to summer, to fall.


    Bookmark   May 20, 2011 at 11:36PM
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jojosplants(9/ Tucson, Az.)

Now why does everyone have to pick on our heat? It only get's to 112 in the summer! ;-) LOL!

Holly , thanks for the info! I'm in Tucson, not far from Phoenix and yes we do get warm. So I plan to research and figure out the best tree.

I did see a few from where you got yours, dwarf, that can take the warmer temps. At least it said so in the description.

And one or two that grow best in bright shade which mom has. Her front yard faces north.

I'm native to Arizona and see the beauty in it that mom doesn't see. I'm happy with our mesquites. ;-)


    Bookmark   May 21, 2011 at 7:54AM
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JoJo - 112 degrees! :blink: Waaayy too hot for me! I hope you can find some JMs suited for your climate; as long as they are nicely shaded, at least in the afternoon, they should be fine.

One nice thing about growing things in Tuscon, at least you don't have to worry about how to overwinter them!


    Bookmark   May 21, 2011 at 11:40AM
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Sorry folks I have a newborn son who arrived recently and I've had to peel myself away from obsessively devouring all the great info on this forum to spend some time with him. I've read through the entire threads on soil, trees in containers, and fertilizer, some of thm multiple times. It is truly a lot to absorb.

Did your tree come in yet? I hope everything is well.

I got the first 6 trees from topiary gardens in new york. Diana was a pleasure to deal with and I'd highly recommend them. They trees arrived in great shape and I've managed to keep them alive so far :-)

The other three trees I ordered came from eastfork nursery in Oregon. Sam was also great and had my trees packed in a fortress that kept them happy on their five day journey.

Ill provide some updated pictures soon on how the trees look after potting up.


    Bookmark   May 25, 2011 at 7:34PM
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Chris and Holly,

I'd be interested to know how your young trees have fared in the 5-1-1 or 1-1-1 potting mix. Please share your experience with us since you first posted 3 years ago.

Thanks a lot!
Kevin in KC

    Bookmark   October 15, 2014 at 4:59PM
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