From Bonsai Pot to Large Pot - Advice needed

mackomon

I bought 2 bonsai's at the 5th World Bonsai Convention for cheap. One is a Satsuki Azalea and the other is a Japanese Red Maple. Both have relatively small trunks and are pot bound.

I want them to grow larger trunks so I plan to put them in large pots. I don't plan to prune any roots, but I believe I should detangle the potbound roots before planting in the large pots.

Questions:
1. Should I leave the roots alone and just detangle them before repotting?
2. Can I use just potting soil (from Home Depot) in these large pots for both the Azalea and Red Japanese Maple? I know that Azaleas are acid-loving, but I only have a small bag of soil mix with kanuma. Will the Azalea do ok in regular potting soil in that large pot?
Also, I know I'm supposed to re-pot the maple before the leaves come out in the early spring. Should I wait until next year to put it into the big pot? I feel sorry for the pot bound roots of this nice maple.

Thanks,
Jimmy

P.S. I just bought a Bougainvillea at a bonsai nursery sale. I believe I got a great price for it. That bonsai will go on another thread with pics! It's my first BIG bonsai. It's sort of a mess, but has lots of potential.

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Aaron_K

Hi Mack,


Ideally, any root work should be carried out on a tree when it is least stressful to do so. This is normally in the spring, just before new growth emerges.

I don't possess an Azalea and so cannot give you any hands on advice regarding it, only that they pretty much must have an acidic soil. The preferred choice is Kanuma. Also repotting is normally performed after the flowers have withered.

Japanese maples should be repotted in early to late spring before the buds break into leaf. That said, I have repotted maples when in full leaf, although no root work was performed upon them. If you do decide to pot into a bigger container, wash the old soil off and use a chopstick or something similar to help tease the root mass out. Try as much as possible to avoid breaking any at this stage. Use a quick draining soil. Akadama is an excellent choice for Japanese maples, although anything like lava rock, grit, larger grained sand, compost that has been screened to removed fine particles will do.

NEVER use regular potting compost. Its the quickest route to root rot and ultimately killing your tree. The reason for this is that the fine particles turn into a swamp when you add water. This greatly diminishes the amount of available air for the tree. Roots begin to suffocate and die and then the rot sets in.

I do use regular compost (along with other components), but it is screened with a soil sieve, leaving me with particle sizes of 3mm upwards. If you don't own one, get a soil sieve set. For my mind, it is a prerequisite for bonsai.

If you do decide to pot the maple tree on, removing the old soil, leave it in a shaded area for a couple of weeks. The Japanese maple should be kept in a shaded area anyway, as they leaf scorch easily in strong sunlight.

Hopefully someone else here will be able to give you first hand advice with the Azalea. It may be too late in the season to pot on, so wait till you do anything.

Hope that helps.

All the best,

Aaron

007

Well . . . I can't say that I fully disagree, and I can't really comment on the Azalea.

However, I can respond to the maple as I tend to favor them in my collection. There was a recent thread on Japanese Maples (the one about distorted foliage) in which it was revealed by a well respected bonsai enthusiast that J. Maples are best repotted in summer dormancy . . . and after seeing his J. Maples, I will follow his advice I can tell you that.

Also, I use standard miracle grow potting soil mixed with a little vermiculite or perlite for my maples in training and have never once noticed any ill effects from doing so.

As for your maple, I'd go ahead and lightly tease appart the roots, remove about 25-30% of the old soil and plant it into a bigger pot with some miracle gro soil and vermiculite/perlite.

That's just my .02 cents . . . .

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agraham

007 says:

"Also, I use standard miracle grow potting soil mixed with a little vermiculite or perlite for my maples in training and have never once noticed any ill effects from doing so."

and i'm glad it wasn't me this time.

andy

malhomme

Jimmy, you may be wondering what to make of this. Well, they are both right.

I've seen Japanese maples grown in everything from a well draining mix as described by Aaron, to spectacular kiyohime maples grown in mud. Yes, literally, mud.

Using an aggregate mix will ultimately give you greater flexibility by not getting soggy then drying-out and becoming hydrophobic. This is why aggregate mixes are considered the "standard". A tree planted in an aggregate mix is less likely to get dreaded root rot.

However, with care trees can be grown in heavier mixes like the one that 007 suggests. Or worse, mud. But the grower must understand how to care for a tree in that kind of soil.

Both are possible.

Cheers,
Jim

mackomon

Thanks for the advice so far everyone. Jim is correct. I was getting a little confused with the mixed messages.

I definitely understand the issues with root rot esp. for these japanese maples. I thought that when Red Japanese Maples are in planted in a large pot (in my case, a large 5 gallon terra cota pot) or into the ground as pre-bonsai to thicken the trunk or just to let it grow more vigorously, people were using regular compost rather than quick draining bonsai soil mixes. It would seem I would need to buy quite a bit of this bonsai soil mix (I don't plan to mix any myself any time soon) if I want to fill the pot.

I think I read the thread about summer dormancy. Will need to pull it up again. I will also make sure that if I re-pot the maple soon, I will give it proper shade and avoid fertilizing for 3-4 weeks. I do plan to use SuperThrive when I initially re-pot the 2 trees.

Anyone with advice about using regular compost for the Azalea. I was planning on using SuperThrive and then Miracid later to fertilize it.

BTW, I didn't realize until after I got back from Home Depot that Miracid has been rebranded/renamed MiracleGro for Azalea, Camellias, Rhododendrons. I guess I will have to go back...

TreeBay

Note to all: I have seen at least two posts recently referring to trees that are described as "pot bound" or "root bound." It's important to reiterate here that state of being root bound is usually accompanied by

• ill health
• inability of irrigation water to penetrate the remaining soil mass, making it difficult if not impossible to adequately hydrate the plant through daily watering
• The tree pushes up and out of the pot, exposing the top third or so of the root ball; or
• the pot breaks.

Just putting a tree in a small container will restrict and impact the root system to some degree. Of course, I have no idea what the actual state of these "root bound" bonsai are: I am making this clarification to avoid having these terms perceived lightly.

Regards,

Matt

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Aurelius

I've never root pruned an azalea, in what could be considered by many, to be pretty late in the year. I realize they are usually mid-late May bloomers. I usually catch them within a week or two after they flower though.
By now, unless your tree was kept a lot further north from you, it probably has 2-3 sets of new leaves on it already. If it is doing so well that it does, then I wouln't say it is "root bound".
If it isn't root bound, don't bother. Catch it next year. If it's really doing crappy you'll be able to tell by years end as it won't set a lot of flower buds.
But I wouldn't be squemish about cutting a few pie wedges of roots out of the often matted layer of roots, if yyou have to. Nothing major, say 10 %.
Just a few precautions if you do.
Keep a similar soil, preferably a moist well draining soil. Simple pine bark and coarse sand will suffice. The point is, don't be filling in your pockets of cut away roots, with very dissimilar soil.
Keep it in the shade/minor sun throughout the summer.
Miracid...the stuff is absolutely perfect for azaleas.

rockm

"Maples are best repotted in summer dormancy . . . and after seeing his J. Maples, I will follow his advice I can tell you that."

This is inaccurate and can lead to some problems. Maples CAN be repotted in summer--but it doesn't make it the best time to do so. They also don't have a summer "dormancy," per se. They slow down as the weather heats up, but they don't go "dormant," in the sense that some Southern U.S trees do in the summer. They are not hot weather trees and haven't evolved the same capabilities as plants from warmer climates. They can put on new growth in the summer heat.

Maples can, indeed, be repotted in summer after their leaves have hardened off in June or even July. This doesn't mean they're dormant. You can even do root work then too, but it's not really the optimum time to be doing so. You can wind up killing the tree if you're too agressive.

Repotting and root pruning for maples is optimally done in early spring, before bud burst. However, summer is fine if you're only repotting up to a larger container, simply wash the old soil off the root ball. Place in bigger pot, work soil into the roots and let the tree alone (in semi-shade).

By the way, it is possible to go with a pot that's too large. Such a container can stay wet to the detriment of the tree. If the pot fills, say, only 1/3 to 1/5 of the pot without the soil, I would be careful. If the soil mass is alot larger than the root mass, the roots will have a difficult time colonizing the soil. See Brent Walston's article on "why a pot is not like the ground" article on his web site evergreengardenworks.com. It is a must read.