Ground Growing vs. Colanders

DrTolhur

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The quintessential technique for faster growth seems to be planting in the ground. But the quintessential technique for great root development seems to be air pruning roots with pond baskets, colanders, Anderson flats, etc. I'm wondering if anyone can compare and contrast the effects of these two practices. It seems like great root development would necessarily lead to a healthy and more rapidly growing tree since there's obviously a balance between roots and foliage, but I don't often see these two techniques talked about together.

Points of consideration for me:
1) Are these two techniques at all related as far as developing young trees, or are they used for completely separate purposes?
2) Is there a reason the root development of air pruning roots wouldn't produce the same level of trunk growth as ground growing?
3) Does it make sense to use both techniques (whether sequentially or together)? Related thread: https://www.bonsainut.com/threads/summer-only-ground-growing-jm.52200/

For context, my personal main concern is with respect to Japanese maples, but the conversation obviously need not be strictly limited to those.
 

caffeinated

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In the ground, vs in a colander, leads to faster tree growth because the roots can quickly grow with fewer restrictions (more than usually desired, meaning - fat and downward) because they're undisturbed, the temperatures are a lot more stable, resources are more plentifully available, and beneficial rhizosphere microbiomes are generally more readily established. Your roots don't come out as refined as you can get in a more controllable container. More root refining generally equals slower tree growth.
 
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Shibui

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The biggest pro for ground growing seems to be stability of moisture, nutrients and temp. I guess root run also plays a big part. I grow a lot of trees in the ground and root prune many annually to prevent the few strong roots and vertical roots issues mentioned.

In my experience air pruning does not always produce magnificent root development for bonsai. The vast majority of root division occurs near the growing ends so in a colander root division happens near the outer ends of the roots, at the colander mesh, rather than close to the trunk where we, as bonsai growers, want it. Lrger colanders just move the ramification further from the trunk. It is a great technique for producing trees with lots of active root tips for landscape planting but when we transfer trees to bonsai most of the outer roots, including most of those new root tips, will be removed when the root system is shortened.
I've found that well managed, regular root pruning gives me much better nebari and root ramification than any other technique.

Colanders can be used in conjunction with ground growing. Plant the tree in a colander and sink the colander in the garden. Roots can grow through the mesh so they reach further but as they thicken are strangled so new roots grow from behind the mesh and end up out in the soil again. This seems to allow better growth than colander above ground (other conditions being equal) but stops the problems of a few large roots running out or down so the trees are much easier to lift when it is time. It still won't address great nebari and roots that ramify right from the trunk but certainly makes it easier to dig the trees.
 

Potawatomi13

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Also consider proliferation of plastical junk added to environment by crap colanders. Ground much better moral decision giving better trunk growth☺️.
 

Lorax7

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Also consider proliferation of plastical junk added to environment by crap colanders. Ground much better moral decision giving better trunk growth☺️.
Pond baskets are much better in this respect than ordinary plastic colanders because they’re intended for outdoor use and made of plastics that can handle UV exposure.
 

penumbra

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I have never used a colander but I have many pond baskets and root bags in use. My root bags are in the ground for fast growth and easy harvest. Most of my pond baskets are in mulch and / or wood chips. Some of my baskets are on pallets so they are used more for root pruning and for plants like my pines that like to go a bit dry.
One size does not fit all.
BTW, I have pond baskets that are 20 years old.
 

Ohmy222

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For most I use pond baskets from 2" to 6" and then use wooden grow boxes with screen on the bottom. Once they go in a box I may use a board, but not always. I definitely prefer to grow in a box/pot. I like seeing it every day, wire it, trim it, and control the growth but both have their place. When you grow in the ground you can't rotate the tree so if you don't have 360 sunlight you will get a one sided tree. My bigger hangup with ground growing is it is easy to forget them. I had some at my old house that suffered or died because they were just out of sight/out of mind. You can easily get a fungal or aphid attack or something and not notice easily. I had a couple that died because we had a long summer period with no rain and since they weren't fully settled in they died. They can be difficult to water too if they aren't near a water source. As for the pond baskets, I like them how they air prune the roots. Not having to deal with circular roots makes root work some much easier.

Ground growing is considerably faster if you don't cut the roots back but then you have to deal with aftermath as you could have big roots, one sided roots, etc. If you do cut the roots back often in the ground then it really slows down the tree and I am not certain it is much faster than a grow box or pond basket. I like ground growing many average to slow species. I don't prefer it for maples or elms they grow too fast and are hard to control. I am very particular about the nebari so I like having more control even at a slower growth. I do use it for some maples that are grafted as I will just layer them above the graft or use as mother plants anyway. I use it for azaleas, K. Hornbeams, pines, Itoigawas, ezos, and for some collected material so they recover. You can leave them in the ground for a while and not have to worry as much. I do think if you grow in the ground, you should use an aggregate soil. I use pumice, perlite, and old bonsai soil (basically what I have laying around). The soil will help you get some good feeders up close. You plant in the ground with normal GA soil and I will just have long roots running all over. I will use a board for the hornbeams but that is about it. As alluded to above, if you use aggregate soil you have to check on them for water, especially until they establish themselves..
 

Kadebe

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Points of consideration for me:
1) Are these two techniques at all related as far as developing young trees, or are they used for completely separate purposes?
2) Is there a reason the root development of air pruning roots wouldn't produce the same level of trunk growth as ground growing?
3) Does it make sense to use both techniques (whether sequentially or together)? Related thread: https://www.bonsainut.com/threads/summer-only-ground-growing-jm.52200/

For context, my personal main concern is with respect to Japanese maples, but the conversation obviously need not be strictly limited to those.
I believe if you can combine the two techniques, you'll get also a nice Nebari.
Use a big colander with 1/4 inch holes. put the colander in the ground. So, the roots grow through the holes without being air pruned. When the root thickness is greater then 1/4 inch, they will be pruned by the colander
 
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Glad this is coming up, by the way. I have one of the quince from Bill Valavanis coming and I've been wondering what to do with it. I have a spot for it and trident maples I want to ground grow. I'm still debating, however - rather than think of it as a single tree I'm working towards, I may think of it as something to take air layers off of.

It sounds like if you want it for a single tree, the pot / basket method is best, but if you want to do the air layer method, ground growing would be best, and because you're air layering, the mucky roots wouldn't matter as much since it's mostly just a host for other trees.

At least, that's what I'm taking away from this discussion. Seems like the air layer method could apply for ground grown Japanese maples, too, vs. pot growing a single tree from scratch. Sorry, bit of a lightbulb moment.
 

Lorax7

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From my perspective, the most important distinction between colander/pond basket and ground growing is that you can work on a tree in a colander/pond basket from a comfortable position, either standing or seated. With ground growing, your only option is to bend down to work on it. I’m happy to sacrifice the possibility of somewhat enhanced growth rate for the convenience of being comfortable while working on the tree. If you leave a pond basket on the ground, particularly if it’s sitting on wood chips or mulch, you’ll get some of the benefits of ground growing when roots escape out the bottom into that loose mulch layer, while retaining the option to pick the tree up and put it on a bench/table when you want to work on it.
 

Shibui

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Ground growing is considerably faster if you don't cut the roots back but then you have to deal with aftermath as you could have big roots, one sided roots, etc. If you do cut the roots back often in the ground then it really slows down the tree and I am not certain it is much faster than a grow box or pond basket.
I grow many trident maples in grow beds. My feeling is that tridents recover from root pruning really quick so they appear to suffer very little reduction in growth over trees that are not root pruned. Any loss of trunk thickening is easily made up by the better taper, better shape, faster healing of scars and better root ramification.
I am planning to put in some side by side comparison trials to get a more objective view of growth rates of root pruned and unpruned trees over 3-5 years to try to quantify how much thickening, if any, I'm sacrificing with annual root pruning.
Growing tridents in the ground with annual root pruning is definitely faster that container growing for me.
I don't find any need to prune tridents in the ground. An annual prune when the trees are uprooted is plenty to develop good trunks.

Slower growing species are treated differently. Junipers are really slow to recover from root pruning so they are left without root disturbance for 3-5 years. Root growth is so slow that large roots has not been a problem over this time scale. For higher quality trunks that involve regular wiring and bending I find pots much easier to manage even though growth is much slower. Sometimes quality is more important than speed.

what about putting a board in the ground and planting the tree on that, kind of like in-ground ebihara
Roots on board still needs attention and intervention to get the best results. The only thing a board can do is shape roots horizontal. No increased ramification, some roots can get larger and thicker, etc. Board is definitely no a magic bullet.

It sounds like if you want it for a single tree, the pot / basket method is best, but if you want to do the air layer method, ground growing would be best, and because you're air layering, the mucky roots wouldn't matter as much since it's mostly just a host for other trees.
Fast grown trees tend to have strong, straight growth with long internodes. Those are not always the best attributes for great bonsai structure. In my experience layers from ground grown trees look good initially but rarely produce great bonsai material.
 

jerzyjerzy

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In my experience layers from ground grown trees look good initially but rarely produce great bonsai material.
Just out of curiosity - how come?

If the tree looks good initially, and then it is grown correctly then why would it not produce great bonsai material. It is a total contradiction here.

Can you explain your train of thought here?
 

Maiden69

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Also consider proliferation of plastical junk added to environment by crap colanders. Ground much better moral decision giving better trunk growth
If people recycled their plastic junk the way they are supposed to we wouldn't have any problem. So my better moral decision is to throw that colander in the recycling bin once it is of no use to me.

Glad this is coming up, by the way. I have one of the quince from Bill Valavanis coming and I've been wondering what to do with it.
If you mean chojubai, look at Omuna's article in Bonsai tonight. He does shohin size mostly, but if you have regular J.Quince you can use the same technique. I have some chojubai cuttings from BVF that I plan on following Omuna's technique, but I also bought a few quinces from Brent that I will still apply the same technique, although I know they will be much larger,

Right now I am doing both methods. I have 2 equal size JBP that I will do the experiment with leaving one in a pond basket and moving the other to a big grow bag like Telperion Farms. I don't have the space to grow in the ground, so I have tow 3'x5' grow beds where I place the bags covered with pine bark and mulch around to maintain moisture. A lot of times people are not getting the results they want with colanders because they don't water and feed the way they are supposed to. Several people, including Jonas, stated that in order to get the maximum benefit from the colander you need to fertilize and water more often.

Also, depending on the tree and the vigor of the roots, planting in a colander and then into the grown would be a futile attempt to contain the roots. I did this with a yoshino cherry tree, and when I went to recover it to plant in a grow bag the colander was torn in several places where the roots had grown through. Thankfully it was in the grow bed and I didn't have to dig it out.
 
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I grow many trident maples in grow beds. My feeling is that tridents recover from root pruning really quick so they appear to suffer very little reduction in growth over trees that are not root pruned. Any loss of trunk thickening is easily made up by the better taper, better shape, faster healing of scars and better root ramification.
I am planning to put in some side by side comparison trials to get a more objective view of growth rates of root pruned and unpruned trees over 3-5 years to try to quantify how much thickening, if any, I'm sacrificing with annual root pruning.
Growing tridents in the ground with annual root pruning is definitely faster that container growing for me.
I don't find any need to prune tridents in the ground. An annual prune when the trees are uprooted is plenty to develop good trunks.

Slower growing species are treated differently. Junipers are really slow to recover from root pruning so they are left without root disturbance for 3-5 years. Root growth is so slow that large roots has not been a problem over this time scale. For higher quality trunks that involve regular wiring and bending I find pots much easier to manage even though growth is much slower. Sometimes quality is more important than speed.


Roots on board still needs attention and intervention to get the best results. The only thing a board can do is shape roots horizontal. No increased ramification, some roots can get larger and thicker, etc. Board is definitely no a magic bullet.


Fast grown trees tend to have strong, straight growth with long internodes. Those are not always the best attributes for great bonsai structure. In my experience layers from ground grown trees look good initially but rarely produce great bonsai material.

super helpful variables for me to think about - thanks! Good to know re internode length in particular!
 

River's Edge

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've found that well managed, regular root pruning gives me much better nebari and root ramification than any other technique.
The above is important regardless of the container or inground. Without regular repotting and root work in the early stages of development, the results are not the same.
I have found that there is some benefit to use colanders in the early stages. I have not found that air pruning only promotes bifurcation at the edge of the colander or pond basket. Quite the opposite in fact.
I have found that it is beneficial to change up to larger containers for the grow out process and prefer Anderson Flats for Japanese maples and tridents.
Once again, regular root work is desired for best results. No less than once every two years is my guideline for fast growing maples. If the flats are placed on the ground then it is wise to trim downward roots going into the ground on a regular basis as well or the drainage is adversely affected.

They will grow faster inground, but I find them more difficult to manage development properly and maintain root work with in the ground growing. much prefer to be able to put the tree on the bench for developmental pruning and root work.

I use the following sequence.
1.seed in tray ( Anderson flat)
2.seedlings in colander when transferred from seed tray. Colander on bench with water system. ( initial wiring to shape trunk movement lower down while still thin and pliable.)
3.year two or three put the colander in a grow bed. ( this allows me to lift for too work, turn and replace at the beginning of each growing season. Continue Wire for movement id desired)
4.Year five place in Anderson flat for continued grow out/ cut back. ( at this point I have established a good starting nebari and some movement in the bottom portion of the trunk by wiring.

Note: two major factors prevent me from growing out in the field.
1. rocky soil in my terrain. Glacial till on the mountain slopes. ( I use raised grow beds to counteract the rocky terrain)
2. Advanced age, laying on my stomach to work on trees is not my idea of fun, doing it from as bent position is even less fun. The raised beds help with this aspect for early stages of development. Would require too much infrastructure to grow out larger numbers in constructed beds.
 

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rustygarden

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Just my 2 cents lol . I grew these carpinus Betulus in my vegetable bed . They were maybe 2 year old seedlings I bought locally . I trimmed the roots and screwed them to a 1x1 ft piece of 3/8 plywood from the bottom . Planted all five in my bed at one end . The bed is 6 ft wide . They grew for almost 3 years and I just dug them . I would do it differently now , such as a 2x2 board and space them out in straight row with space all around . But as you can see not bad growth . And nice and flat root base . Not the best but a good start . I would also bury them deeper say 3 to 4 inches . Four of the five turned out pretty nice .IMG_4310[7742] carpinus 2022.JPGIMG_4313[7748] carpinus 2022.JPGIMG_4312[7746] betulus 2022.JPGIMG_4325[7798] carpinis betulus .JPGIMG_4330[7802] carpinus betulus.JPGIMG_4321[7788] carpinus 2022.JPG
 

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