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Re-potting Japanese Maple - Looking for Advice

7 years ago

At the end of fall last year, I purchased a small Japanese Maple (Peaches and Cream) that was on clearance for $10. It was pretty much dormant when I got it. I stored it outside, in a sheltered corner, behind my shed. We had a relatively mild winter, though there definitely were some cold nights in the high teens.

I have no idea how to tell if it survived the winter, but assuming that it has I’m trying to make plans, since I feel like spring is just around the corner. Although I’ve grown several house plants with some success, I’m essentially a noob. Last year, I discovered this forum and learnt a tremendous amount with regards to soil, watering, fertilizing, root pruning, etc…. Most of this came from reading many threads maintained by Al. I have yet to put any of this newly acquired information to use yet, but it is now time!

My long term plans for this tree (assuming it is alive) is to grow it as a bonsai. I’ve never grown or taken care of a bonsai, so all I have is some basic knowledge from reading forums and watching videos. That being said, I’m not in a hurry. At this point, all I want to do is get it on the right path. This is what I plan to do this year, please provide any advice or guidance as you see fit:

  1. Wait to see some signs of budding (I want to know if it’s alive).
  2. Re-pot into Gritty Mix, including some root pruning.
  3. Prune the very top of the tree to promote growth on the lower branches.


I have a few small questions I’d like to pose.

  1. How long is my window of opportunity for repotting? When is it too late?
  2. What size of pot should I use? Is shape important?
  3. I will be using Dyna-Gro FP, do I need gypsum in the Gritty Mix? (I think the answer is no)
  4. How aggressive should I be when pruning?


Any advice you would like to share about what to do in the next couple years?

Thanks in advance,

Pat


Comments (20)

  • 7 years ago

    The evidence of budding is a critical factor. Japanese maples produce buds in fall that winter over - these should be present now although still dormant. Examine them closely to see if they are still viable......they should be somewhat succulent looking, not dried or dark colored. The roots of containerized JM's are quite sensitive to cold temperatures and can sustain damage in the mid 20's so we can only hope for the best that yours survived the cold.

    I have repotted my JM's at all times of the year without issue. Root pruning is a bit different and is typically suggested to be done while the tree is still dormant. But these little trees are quite a bit more resilient to rough handling than you would imagine so I would go ahead and do what you need to when you have confirmed it is still alive.

    Pot shape is not important - pot size is but if you are going to be bonsai'ing, you'll address the size container by the size of the root system (and therefore the size of the tree) you are trying to maintain.

    I don't use gritty mix with my JM's - I prefer the 5-1-1 (or a very close facsimile) as it is more moisture retentive and I don't have to water daily in summer. I omit any gypsum but I do use a CRF when potting and again each spring. I also use a Dyna Gro product (GROW, not FP) infrequently a few times during the growing season to supplement the trace elements.

    Although I have a large collection of JM's in containers, I do not bonsai them but let them grow naturally. So my pruning is negligible :-) I will leave any pruning suggestions to those who practice bonsai more intently!

    Your biggest issue going forward will be addressing the watering needs during the growing season. These are not very drought tolerant plants and the heat of summer coupled with a small bonsai pot and the very fast draining gritty mix could require daily - or more often - attention. And winter protection - ideally these containerized plants should be stored somewhere where the temps stay between 30-40F - not any colder nor much warmer.

  • 7 years ago

    Gardengal, thanks so much for your response. I've taken another look at the tree, and based on your description of what the buds should look like, I'm not super hopeful. I don't really want to go through the whole re-pot procedure for nothing. So, I wait to see signs of life. For next winter, I'll have to come up with a solution. Maybe build an insulated box over the container to protect the roots.

    Your point about moisture retention is a good one. New England is a couple zone cooler than yours. But, it definitely gets hot in the summer. I will be using Gritty Mix for a houseplant, so I figured I'd just use the same mix for the JM.

    If you don't do much pruning, I have to assume that your JM trees get pretty tall.



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  • 7 years ago

    New England is only cooler in the winter - that is ALL the hardiness zones indicate :-) 85F here for more than 2 or 3 days during the summer is considered a major heat wave........we just don't have hot summers.

    Growing any tree in a container is a natural dwarfing process......bonsai training just amplifies it substantially. I do root prune and repot mine so that also tends to keep them smaller without the need for much pruning.

    Pat thanked gardengal48 (PNW Z8/9)
  • 7 years ago

    Pat, post some close ups of the buds. You can also do a scratch test to see if there's green tissue under the bark.

    I, too, use the 5-1-1 mix for my maples, as it gets very hot here in northern California. The buds are starting to break on a couple of my maples, so I repotted them this afternoon into larger containers.

    Josh

    Pat thanked greenman28 NorCal 7b/8a
  • 7 years ago

    Hi, Pat. I got your message but have been way behind on my mail from Houzz. It's windy/cold/raining today, so I gave up repotting and am trying to get caught up.

    I have a few small questions I’d like to pose.How long is my window of opportunity for repotting? When is it too late? The best time to repot is between the onset of budswell and the beginning of leaf emergence. If you repot at beyond that point, you should reduce the canopy somewhat or the tree will decide what branches it might wish to shed, and that can be an adversity for a budding bonsai practitioner. You can pot up any time, but there is still a favored time for that, which would be when the tree is actively growing and will have time to colonize the fresh soil with roots before it sheds its leaves in the fall.

    What size of pot should I use? Is shape important? Shape isn't important, but do give some consideration to whether or not you'll be able to easily remove the root/soil mass from the pot when it's time to do so. Pots that have lips curling inward or rolled to the inside are often difficult to work around at repotting time.


    To a large degree, appropriate pot size is determined by soil choice ..... on a sliding scale. The more water-retentive your soil is, the more critical pot size becomes, If you were growing in a well-made gritty mix, you could plant a single seed in a 55 gallon drum full of soil w/o concern you might be over-potting. Your soil choice is a major factor in how much of it's genetic potential your plant will be able to realize. The 5:1:1 is fine if you like it for growing on, but when you finally put the plant in a shallow pot, you'll want something that holds very little perched water. I use the gritty mix for all my bonsai and future bonsai, switching the trees over by bare-rooting at the first repot.

    I will be using Dyna-Gro FP, do I need gypsum in the Gritty Mix? (I think the answer is no). That's correct.

    How aggressive should I be when pruning? The top (branches) or the bottom (roots)?

    Any advice you would like to share about what to do in the next couple years? Well, it's unlikely any of the existing top growth would ever be part of a bonsai composition. So, keep an eye out for any new growth very low on the trunk. It's likely your first chop will be to a point just above that as yet nonexistent branch. Also, your tree is very likely grafted, so make sure the graft union is low enough to allow the tree to represent what it says it is on the ID tag and not so ugly that it precludes the use of the tree as a bonsai.

    IF you have an inkling you might not use the tree as bonsai material, I'd prune all the branches back to a single pair of buds, and eliminate all trifurcations on the tree. This will slow growth and development a little, but you'll have a much finer structured tree in the end if you don't use it for bonsai.

    This is an Acer p I started as a cutting ^^^. It's coming into its 4th year in a pot. There are no bifurcations anywhere on the tree. I always intended it to be a potted JM rather than a bonsai, but if I wanted it to be a bonsai I could do so by cutting all the upper branches back and reducing the lowest branch to a few leaf buds. This will force back-budding low on the tree. I would then train a low branch into the position I want it to be in, then chop the tree back to immediately above that branch in spring of '18.

    Al

    Pat thanked tapla (mid-Michigan, USDA z5b-6a)
  • 7 years ago

    Thanks to everyone for your thoughts and advice. In particular to Al, who must get many questions and does a masterful job of providing information to this community.

    I've keeping my eye on the tree, and I'm somewhat optimistic that it will wake up. Most of the branches look "dead", but a few are showing what I think are signs of life. I've got my Gritty Mix components all sifted and ready to go.

    I'm posting a few pictures. The first is of what I think are dead buds, and then a few of what I think are buds swelling?. The last picture is of the stem/trunk which shows that Al is once again right in that it looks to be a grafted tree.

    Al, if I interpret your pruning advice, it's to basically encourage back-budding lower on the tree, by pruning the top (ensuring to leave of buds). Then once a lower branch is established, chop the trunk above that point. As a general multi-year plan, I can strive for that.

  • 7 years ago

    Yep, the tree is alive.

    Josh

  • 7 years ago
    last modified: 7 years ago

    Pam and Josh are no slouches when it comes to good advice, either. ;-)

    Tips: Prune every branch back to 1 pair of buds and remove trifurcations. A bifurcation looks like a slingshot. A trifurcation looks like a trident or pitch fork. Acer is programmed to grow in trifurcative form, a central branch with buds/leaves arranged in opposite pairs along the branch.


    In the forth image from the top, you'll see buds emerging from the branch collar. There are already 2 living branches growing from that point, you do not want more. Those buds should be rubbed off with your thumbnail or some other tool that will rub them off w/o damaging tissue.

    In the same image, you'll see a branch wedged into a crotch formed by a little spur. That needs fixing. Prune off the spur, prune the branch back to a point immediately distal to the pair of buds, or farther back if there are more buds behind the pair in the picture.

    If you have branches on the tree that are growing too close to another branch, like in the first picture you posted, cut a piece of wire or a thin brad and wedge it between the branches that need to be separated. In a couple of months, you can remove the wire and the branch will retain its position.

    Finally - Every bud on your tree represents a new branch. When buds start opening, the first set of leaves will be very close to the branch; but then your tree will shoot out a very long internode if you don't take some control over how it grows. AS SOON AS the first set of leaves emerges and you can see the central branch extending, pinch it out immediately.

    What happens if you pinch out the leader the first day it's visible: The 2 leaves you left will mature. From both of the axils (crotches) of the leaves you left, 2 new branches will form. These will push out a short internode with a pair of leaves, then a very long internode. Instead of letting that long internode grow, repeat the pinching process again. That way, you end up with a very compact and full tree with no long internodes. Once the tree gets thousands of growing points instead of a hundred or so like it has now, the internode length will start to decrease on it's own and you won't need to pay as much attention to its development unless you prune very hard and reduce the number of growing points.

    Al

  • 7 years ago

    Thanks again to everyone for their advice so far. I re-potted the tree this weekend. I'm sure I made some very questionable pruning decisions, but hey, I have to start somewhere. I was fairly timid on pruning the top. I simply tried to remove many of the trifurcations. If it lives and has a good year, then I'll re-pot again next year and take a bigger swing at it.

    My Gritty Mix, pre blending.

  • 7 years ago
    last modified: 7 years ago

    Keep it out of sun and wind until the leaves start to open. When you see the next order of branches starting to grow, you can give it some sun and fertilize if you wish. I usually wait to fertilize until the first sets of leaves have matured. That helps to keep internode length shorter. Don't forget to pinch out the center of the extending branch after the first pair of leaves emerges. It makes a very significant difference.

    Al

    Pat thanked tapla (mid-Michigan, USDA z5b-6a)
  • 7 years ago

    Yes, pinching out the center of the extending branches is my main objective this year. I'm quite looking forward to paying close attention to the tree to observe it's growth habits.

    Thanks for the tips about sun, wind and fertilizing. I shall do as recommended.

    Pat



  • 7 years ago

    Good work, Pat.

    Josh

    Pat thanked greenman28 NorCal 7b/8a
  • 7 years ago

    Good news! Looks like the tree is doing well. I am very happy, thanks again to everyone.

    Here are some photos of me pinching out what I believe to be a central branch. I do have a question though. I've been looking at other JM in the "wild" and in these trees it seems like the central branch is generating seed pods. Am I pinching out seed pods, or the branch extension? Just curious.


  • 7 years ago

    Great!

    Your plant will tend to get VERY long branches if you don't shorten them every year. Next spring before your tree wakes up, prune all branches in the top 1/3 of the tree back to the first pair (most proximal) of buds on every branch and remove any heavy branches with a flush cut to the lower order branch. You can actually do that now, if you like. The trunk is the first order, branches growing off the trunk are second order, branches off the second order are third order, etc. While flush cuts are to be avoided on trees in the landscape, they are preferred for trees in pots because the wounds heal faster. You'll need to keep the top in check so you don't get heavy branches, which make the top look unnatural. Your tree will automatically want to spend 2/3 of the energy (food) it makes in the top 1/3 of the tree. You must restrain the top if you want the lower branches to develop (thicken). If you don't restrain the top, the lower branches weaken and die and you end up with a lot of bulk in the top where branches should be fine and twiggy.


    Al

    Pat thanked tapla (mid-Michigan, USDA z5b-6a)
  • 7 years ago

    That's purty!

  • 7 years ago

    Pat - you should limit your pruning to the cooler months and Winter; when the sap's not flowing. Knowing your Winters, you might want to consider overwintering your tree; in a pot in pot set up. Put your tree as is (with pot) into a larger pot, then fill it in with mulch. This will give the roots enough insulation until you transplant it next year. You also might want to wrap the trunk, and buy or make a tree cover to protect against cold and wind.

    I just now took these pics, and my tree began leafing out about 3 weeks ago. I used the Pepsi can for size comparison. I put my tree into a rather large pot to give the roots insulation; in addition to, Two layers of insulation wrapped around the pot.



    Your tree is probably hardy to zone 5, but above ground in a pot; you have to add 2 zones.


    Rob

  • 5 years ago

    Hi I just acquired a Bloodgood Maple. Seems like it was maltreated at the big box store. It has 1/3 of the leaves it is aupposed to have. The rest are branches that seem to look like in good shape. They have red buds on them, kind of a lot of them. I would like to know if you think they will put out news leaves this fall or if they will stay like this until Spring of next year. My other treea are putting out new leaves now that the high Summer has passed and I'm wondering if mine will do the same. The branches with buds look the same as picturw number 2 of the 4 pictures that Pat posted above. At the top of the tree are are brand new red leaves that have just started coming out and developing, maybe a month ago. The soil is pine bark based and seems to drain very well. The tree has green wide leaves at the center that seem like getting old, do they turn green after they come out red or do they turn red after they come out green? Let me post a picture of it. Thoughts?



  • 5 years ago

    First, I doubt you have a Bloodgood - the leaves are far too small/lobes too narrow, even on a young tree, for that cultivar. There are a lot JM's being sold as Bloodgood that are just seedling trees. That could account for the leaf aberration as well as the coloring. Bloogood is a very deep wine red color, although it can bronze up or lose some of its redness in full sun in hotter climates. But it should never have distinctly green leaves like what is showing in your photo.

    And no, it will not produce any more new leaves now. It is fall and the tree will be entering dormancy soon and dropping what remaining leaves it has.

    I hope you didn't pay much for it :-) It is in bad shape, suffered some serious drought stress and looks like it has some tip dieback as a result.....not to mention a good likelihood of labeling issues.

    Just get it planted and hope for the best in spring.

    btw, if you have more questions, it is advisable to start your own thread rather than tacking on to an old, stale one. And there is forum dedicated specifically to maples as well that will give you very precise JM advice.

  • 5 years ago

    That makes sense. Maybe this is a fireglow, or another. I discovered it has powdery mildew. I will post a new thred in Maples to ask for advice on this new tree. Kind of an emergency tree rehab thread. I'm a sucker for fixer-uppers. By the way I'm not planting it I only grow in containers I don't have a garden. Im kind of sad it's not a Bloodgood but it's okay because what I wanted was red leaves so this one is okay. Let's continue in the new thread?