AusBonsai

I was thinking this post could be a good resource for ground growing.

The species I'm planning on ground growing this year are:
- Itoigawa
- Kishu
- JBP
- JRP
- Hinoki Nana
- Japanese Maples
- Various Elms (chinese, corky bark, zelkova)

I'm planning on giving them:
- around 1sqm of space, depth of 150-200mm
- bed of sand (1-6mm sand, depth of 1cm+)

The mix I'm planning on using for the junipers and Pines is: 80% 1-6mm sand, 20% pine nuggets (would coco coir work in place of pine nuggets?)

Planning on digging up every 2-3 years to give it a good root prune.

Also positioning. I'm planning on full sun for conifers, west side of yard near fence for deciduous (for afternoon shade).

Main motivation for growing my own is that I can't find any Shimpaku of the size I'm after, and if I'm going to this effort I may as well ground grow a bunch of other things.

Any suggestion on mix for the others would be appreciated, or any suggestion on what to change (space, depth, etc.)

Elms… make sure they are away from the house. They rocket

Daluke wrote: ↑June 25th, 2023, 3:31 pm Elms… make sure they are away from the house. They rocket

I have a few Chinese elm in the ground at the moment, planted into garbage soil (before I knew about open mixes). They've grown like crazy this past year.

Lucky i have a tile underneath it because I've heard they can grow from roots, so it could be hard to get rid of if I've just let it grow.

Chinese elms can rapidly get away if you let them. Many years ago I planted trees and left them for 5 years to thicken. Really difficult to dig with the shovel so I borrowed a back hoe but bent it trying to get a big Chinese elm out.
Now I dig more often so roots do not get out of control.
I doubt that a tile will make it any easier. Roots will still thicken whether there's a time of not. The only advantage would be that it may be easier to cut horizontal roots than vertical ones right under the trunk. Let us know when you get round to digging.
Regular root trim makes it easier as roots don't get a chance to get so thick I cannot chop through with a spade.
Chinese elms do grow from roots. Each year I get a new crop growing wherever the elms were dug. Just need to keep chopping those suckers so they don't take over.

2-3 year may be long enough for junipers and pines but my junipers are generally very slow for a few years so I rarely dig them before 5 years. Fortunately pines and junipers do not seem to develop thick, hard roots so are still easy to dig even after 5 years free growing.

My grow beds are just the existing topsoil with added compost and manures. Maybe some of your soil could provide the moisture holding component with the sand instead of pine or coir.
Coir chips would be a reasonable alternative to pine bark if you want to maintain the open structure.

From my experience (over a decade of ground growing):

I wouldn't over-analyse and spend too much time blending the soil you plant them in - as long as it is decent natural soil, the trees won't mind. I have used what were previously vegetable garden beds as growing beds, and all tree species loved it.

I was growing pines for trunk thickness, and deciduous for nebari - decide what you want to achieve before you embark. Trunk thickness will look after itself in the ground, but you need to manage the trunk and nebari for a good end-result. Trunk thickness is easy to rapidly achieve in the ground, but if not pruned appropriately, can result in a sub-grade tree with long trunk internodes, sparse branches, and sub-par nebari.

My recommendations for each species:

Elms - as mentioned above, they can get away from you before you realise - especially the nebari. One running root left for a season can destroy the future nerbari. Lift and shave the roots back to a flat profile every 2 years at the minimum.

Maples - same as elms, though I have had better results lifting them annually. If you want to go next-level, add to the nebari with multiple root grafts each season.

Pines - plant into the ground inside a 35-40cm plastic colander - you'll be glad you did. Makes digging them exponentially easier. I lift them only every 3-4 years, and do not focus so much on the nebari - it is the trunk development that can get away from you in a single season. Once in the ground, you need to establish the next leader of the trunk before you let a sacrifice branch go. This may involve hard cut-back or decandling one season to establish the buds for continuing to grow-on (a set-back to growth rate). Then keep decandling the future-leader to hold it back and also establish short internode length for the future branch structure as well as the next leader and sacrifice for when the current sacrifice has accomplished the target girth. You will find you are ALWAYS thinking ahead 2 seasons, and trying to establish the structure for the next step before letting it grow.
Once you start achieving multiple low-set branches at short intervals, you need to try and maintain these during the trunk-growing years - this requires annual decandling and energy balance of the achieved branches to hold them back, while letting the trunk grow via sacrifice.

From my experience, pines love full sun, as do chinese elms and tridents. Japanese maples like mottled sun, even in the ground. The trees seem to be able to take more sun in the ground.

Thanks for the info.

wrcmad wrote: ↑June 25th, 2023, 8:17 pm Elms - as mentioned above, they can get away from you before you realise - especially the nebari. One running root left for a season can destroy the future nerbari. Lift and shave the roots back to a flat profile every 2 years at the minimum.

Just wanted to clarify a few things.

Re: elms, (assuming I have the time) is it better to root prune every year? Or better to wait 2 years before lifting? (I wasn't sure what you meant by 2 years at the minimum).

Re: pines, I was planning on planting the pines in colanders, good to know you recommend it as well - how often do you lift them out of the colander and root prune the inside (if ever)?

How thick do you let your sacrifice branches get, before cutting them off? I've seen really thick ones (4-5cm) but I assume those scars will never heal over. I was thinking 20c size maximum?

With establishment of the next leader - how do you decide when and how to make that transition? I guess it depends on the intended finished size of the tree, but any advice you can give on how to gracefully transition to a new leader would be most welcome. Taper is very important to me, and I'd be willing to slow down growth to get good taper.

Maintaining low-set branches - this wasn't even something I had thought of, but it makes sense. I was thinking I'd just try and keep inner growth healthy as much as possible, but why not ramify and build a branch whilst I'm ground growing...

There are many ways to skin a cat.
In respect to ground growing elms (and I speak primarily about Ulmus Parvifolia) they rarely throw a decent nebari without regular and severe root pruning. For young, developing stock in the ground I would be lifting annually and pruning hard to get a decent foundation.
For pines, I don’t use a colander but that doesn’t make my technique better or worse than others. I also pull mine up and chopped back quite hard within 2 years… but the trees I plant already have some decent root work applied before I put them in the ground. Take from that what you will, but I guess the main thing to understand is whatever direction you head there are always nuances and things about stock and the way they have been developed (or not) before/during/after ground growing that might have an impact on the outcome. It’s kind of like people talking about how decandling can affect a pine without mentioning the fertilisation regime etc required for the months beforehand to get it ready for the process. That dictates the results from the process as much as cutting back itself.
In relation to taper and transition between sacrifice branches, that can only really be determined when trees have been properly developed to have progressive options to cut back to and thus develop a new sacrifice from. Very easy with trident maples/Chinese elms etc … a bit trickier and more thought/preparation required for pines. I can’t really say for juniper with any first hand experience but I assume they are somewhere in between. Swapping out between sacrifices no matter what species though is always preferential to developing one large sacrifice that leaves a huge scar once removed. In my opinion of course. Transitioning between leaders is absolutely dictated by how big you are looking for the finished tree to be as well as where the sacrifice lies on the tree. Those at the top are thickening the entire trunk whereas those coming from further down are only thickening the trunk below. I would leave a sacrifice that originates lower on a trunk therefore for longer than one that is higher if my primary aim is to increase taper.

SuperBonSaiyan wrote: ↑June 25th, 2023, 9:13 pm Re: elms, (assuming I have the time) is it better to root prune every year? Or better to wait 2 years before lifting? (I wasn't sure what you meant by 2 years at the minimum).

I lift them every year until a good, even-spread nebari is established (maybe for the first 3 or 4 years). After that, you may be able to get away with only lifting every 2 years, but you will still need to get in there and have a scratch around the base to make sure do don't have any potential running roots before leaving them in the ground for a 2nd consecutive year. If in doubt - dig.

SuperBonSaiyan wrote: ↑June 25th, 2023, 9:13 pm Re: pines, I was planning on planting the pines in colanders, good to know you recommend it as well - how often do you lift them out of the colander and root prune the inside (if ever)?

I don't lift them out of the colander until the trunk is where I want it. In fact, if the tree remains healthy and vigorous in the ground, I don't even dig it out around the colander until the trunk structure is complete. For example, Last spring I dug a JBP out of the ground (around the colander) for the first time after 7 years of growing at 140mm base thickness - final tree height will be about 400mm. this year I will begin the process of replacing field soil and establishing the shari.

SuperBonSaiyan wrote: ↑June 25th, 2023, 9:13 pm How thick do you let your sacrifice branches get, before cutting them off? I've seen really thick ones (4-5cm) but I assume those scars will never heal over. I was thinking 20c size maximum?

Pines are as capable of healing as any species while you are still growing them. Thus, for me, the first cut is usually quite a chunky one at around 50-70mm thick. (Now I am running around the yard in the dark with a tape measure and torch ). For example, the JBP I mentioned above was first cut at around 60mm thick, with an established replacement leader around 10-15mm. I used putty on the wound and it healed over completely in 3 years while growing on. I just cut one last month at around 70mm with around a 20mm replacement leader, and expect it to heal over in 4 years. Progressive cuts are at lesser diameter, as you move up in height - to produce taper, so still heal well. The slowest cut to heal is the last cut.

SuperBonSaiyan wrote: ↑June 25th, 2023, 9:13 pm With establishment of the next leader - how do you decide when and how to make that transition? I guess it depends on the intended finished size of the tree, but any advice you can give on how to gracefully transition to a new leader would be most welcome. Taper is very important to me, and I'd be willing to slow down growth to get good taper.

You got it in one - It depends on your size/girth-goal. My rule of thumb for ground-grown JBP is that if you want good taper and use the grow and cut method, the final diameter will end up being 2-2.5 times the diameter of the first cut. The closer you make each cut to the last, the more pronounced the taper, and the shorter and squatter the final tree becomes. I like fat trees - like Japanese-style, so generally cut at about between 50-100mm above the previous cut. I never cut until I have set the new leader to take it's place, and as soon as I have the new leader set, I start on establishing the following one.
Transitioning to a new leader is easiest said in a pictorial - but please excuse my crappy artistic abilities :


Bottom line - ground growing a good tree gives stellar results in a way shorter time frame, but digging, sorting the roots, and replanting is really hard work. Well worth the effort though IMHO.

Edit to add - one thing that I consider imperative..... when you first plant a young tree in the ground, plant at an angle (even a small angle) so the trunk will rise out of the soil at an angle. There is nothing more synthetic than the first section of trunk being as vertical as a post, unless it's a broom or formal upright.

wrcmad wrote: ↑June 25th, 2023, 10:53 pm Transitioning to a new leader is easiest said in a pictorial - but please excuse my crappy artistic abilities :

JBP1.jpgJBP2.jpg



Bottom line - ground growing a good tree gives stellar results in a way shorter time frame, but digging, sorting the roots, and replanting is really hard work. Well worth the effort though IMHO.

Edit to add - one thing that I consider imperative..... when you first plant a young tree in the ground, plant at an angle (even a small angle) so the trunk will rise out of the soil at an angle. There is nothing more synthetic than the first section of trunk being as vertical as a post, unless it's a broom or formal upright.

That made it crystal clear, thank you.

And your explanation about how growing helps cuts heal is very helpful too - I can be a bit more courageous with my sacrifices.

How were the roots inside the colander when you eventually removed them? Were they mostly feeder roots or had they become lignified & formed part of your nebari? The way I'm imagining it going (since you're always cutting back outside the colander) is that feeder roots would have to remain inside the colander, and you'd probably have a relatively flat section underneath from the big root cutbacks callusing over.

SuperBonSaiyan wrote: ↑June 26th, 2023, 8:53 am How were the roots inside the colander when you eventually removed them? Were they mostly feeder roots or had they become lignified & formed part of your nebari? The way I'm imagining it going (since you're always cutting back outside the colander) is that feeder roots would have to remain inside the colander, and you'd probably have a relatively flat section underneath from the big root cutbacks callusing over.

Roots in the colander after digging out were surprisingly finer than I expected. A few stray thick ones, but not too many. As stated before, I rarely dig them out before the trunk is developed, though every few years I might run a spade around the outside of the colander for an in-ground root prune.
I don't plant into the ground as a seeding until the roots are sorted to a degree (hence 2-year old), and in the ground they are mostly free to spread, even outside the colander, so I have found the all-too-familiar fused ball under the base does not happen - it seems to be a thing I have found more with pot-grown JBP where the roots get bound up by the pot.

Sounds like a good plan that you are starting some ground growing. I have had a grow bed for the last few years, and I have found some things work better than others - most recent change is to raised the level to improve drainage. This was only a problem in one of my two small grow beds.

My observations:

Spacing - Plant in rows so you can access from one or both sides and need 600mm between plants to avoid shading out. Then on one side (or both sides) need a bigger gap to access, you will need to get down low to have a look at what is going on from time to time.

Drainage - raised bed is good if your planting area does not already have good drainage. I have had success with raising the soil with: Garden Soil, potting mix, used bonsai soil, pine bark mulch, sand, coco coir chip and fine. I have had best result growing directly in the soil where there is good drainage. Next best I have had good results in a growbag sitting on top of soil, raised above ground level.

Mix - if you are planting in an open mix as you suggest, then you need a raised bed. If you plant below the natural ground soil level with a open mix, you are essentially creating a sump which will collect water and not be good for roots. The latest mix I have just made up and about to use is 70% perlite(3-7mm)/30% coco coir (60%fine/40%chip). The bonsify youtube video suggests 80%perlite/20%coir for development.

plant in/on:
- I have tried planting on a tile/plywood and this can create a root spread, but it tends to make a wet spot directly under the trunk which deters fine roots from growing. this seems to end up with 3-6 big roots spreading out, then the fine roots being out past the tile.
- I have tried some geofarbric under the trunk, this can create a root spread, but seems to keep fine roots growing close.
- I have tried grow bag. I find this does retain alot of roots - I have tried to lift and rotate 180° after 12 months - this is a benefit for me as one side is shaded from morning sun, and that side of the trunk develops minimal branching. The other benefit is you can lift the tree and check out the trunk, but this slows growth.
- I have seen the colander - it had 5mm+ holes and did not seem to retain much roots

Digging up & Root work: there is benefit for developing the nebari early of digging up and root pruning yearly, there is a benefit of trunk growth for leaving grow for multiple years. You need to weigh up the benefits of each:
- If you want a superior Nebari - my plan would be to dig up yearly for first 3 years dig up yearly and do root work and replant in ground. Keep doing this as many years as it takes to get the desired Nebari, then leave it longer for trunk development
- If you only grow for 1-2 years, you will not get explosive growth.
- If you want the biggest trunk - wait 3-5 years, the dig up.
- see my very rough drawing.
Top Down Repotting method: works well if you have a plant in a 300mm deep pot and you want to transfer it into a 100mm deep bonsai pot – this works perfectly for the grow bags or regular growing pots. Checkout the video on youtube “Top-Down Bonsai Repotting Technique for Field-Grown Trees - Tom Fincel at Farm To Table - BSOP”. I tried this in the last year on repotting down from deep pots into shallow pots. You remove all soil from top 100mm, leave the major roots which go down into the bottom 200mm soil, in the top 100mm adjust root spread, remove crossing roots, be as hard as you like on getting the top 100mm adjusted. Then repot with good bonsai potting mix in the top 100mm, wait 2 years and it will barely miss a beat as the major roots in the bottom 200mm are still in place, then just cut right through all roots below the top 100mm (I have not tried this part yet) and put into a bonsai pot and it will supposedly barely miss a beat as the op 100mm of roots have formed fine roots with a good spread. For elms you can keep the bottom 200mm as ready made root cuttings.

Pruning:
- some work needs to be done to establish some style before plant in the ground. or alternatively lift and do styling and replant into ground
- keep in mind if you grow multiple sacrifice branches as well as the trunk these can quickly create reverse taper.
- multiple sacrifice may be the desired multitrunked style
- depending on the style, may be better of focusing on a single sacrifice + setting up the next sacrifice as described well by WRCMAD.
- for junipers, i think you just need to grow with minimal pruning - say every 2 years.

My current growing setup involves trailing 2 separate grow beds
one in natural soil with great drainage.
- grow directly in soil, dig up every year & Root prune, prune top at some time, replant into ground.

second one is in a low spot with poor drainage
- Raised garden Bed - 150mm above natural soil level.
- Basic bending done before planting
- Grow in grow bags, open mix 70% perlite, 30% coir, approx. 100mm down have a layer of geofabric. put grow bag 50mm into raised soil + 75mm mulch around grow bag.
- Pruning as described by WRCMAD
- Grow for 3 years, dig up & Root prune, replant into ground. May trial 5 years for second growing time after having done some root work.

Is there any suggestions on how thick to let sacrifice trunk before pruning to get benefit of trunk size but still a healable wound? And is it different for each species?
- shimpake Junipers
- Japanese black Pines
- Maples
- Elms

Same question for sacrafice branches? Do you let them get thick or focus on the trunk?

Consider converting sacrifice branches on shimpaku juniper into dead wood feature. Dead wood is a natural part of wild juniper, a great way to use sacrifice branches and no worry about wound healing.
Otherwise similar to below.
Maples, pines and elms heal well but you need to allow growth above the wound to promote healing. Early pruning will usually be followed by heaps of further growth while still in the ground. No problem healing 5cm wounds in that case but as you gradually slow growth near the end of development healing gets much slower so make big cuts early and progressively smaller later in development.

A question about controlling weeds - I was planning on using landscape fabric (aka weed mat).

I read on another (USA) forum that the stuff available through retail is too thin and not great, so go for commercial landscape fabric. Is the stuff available from Bunnings here of decent quality? or should I find a professional supplier? Any suggestions on brand, thickness, specs to look for?

Also - how do I use landscape fabric? Do I kill all weeds below and clear them out before laying it? Or just kill all weeds and lay on top of the dead weeds?

Finally (I'm planing in a raised bed) do I establish my bed on top of the landscape fabric? Or do I cut a hole out and build the bed on top of raw soil (weeds removed on this section for sure).

Thanks!

Weed mat is of different qualities. Even the green shed has a range of different qualities and prices.
I have only used the cheaper woven weed mat and only for fixed installation. It does break down and leaves miles of tough plastic strips. When weeds grow through the fabric it can be real difficult to remove.
For the grow bed you will be taking it off every year or 2 to access the roots so probably better to go for reasonable quality.
Or go for something that's biodegradable. Sheet mulch with cardboard or newspaper covered with something to hold it down against wind works very well and should be broken down by digging time. If it decays early then simply put on another layer.

Preparation depends on the weeds you are dealing with. Annual weeds are easy. Just laying the weed mat or sheet mulch over them should kill them.
Perennials are another problem altogether. Couch, bent grass, oxalis and sorrel are the biggest menace up here. All will grow from pieces of root and most will find a way through weed mat.
I try to start with a cleanish area so spray with glyphosate now to kill off as many weeds as possible before planting. Spray well before any digging if there are perennials as most can grow from small pieces of root.

Weed mat is not a magic bullet. Unfortunately weeds will still come - seeds blown in on the wind, birds or from some organic fertilisers so you will still need to do some spot weeding as they turn up. The trick is to try to keep ahead of them so try to weed well before they set seed and spread further.

Raised bed on weed mat depends on how high the bed is. If it's over 50 cm high you could use wed mat under but shallower it will tend to get in the way when digging and may even prevent tree roots from going deep to get good growth.