How and Why To Grow A Bonsai In The Ground

When you get into bonsai and start with a small or young tree you will probably hear the advice “Plant that in the ground for a few years”

The goal of planting a bonsai in the ground is to quickly thicken the tree up and jump start its development as a bonsai.

This general advice can often be very wise, but only if you follow the process properly.

What Happens To Bonsai When You Plant Them In The Ground?

A bonsai tree is just a normal tree that has been manipulated by us to stay small, once you plant it back in the ground it will start to act like a normal tree again. It will try to grow in to full size tree.

One of the main reasons a bonsai stays so small is due to the limited growing space in the small pot. Once you plant a tree in the ground this space restriction is removed and they will quickly start to stretch out and take advantage of the endless room available to them.

The roots are allowed to expand freely and will be able to move more water and nutrients up into the tree. This will result in more top growth. This extra top growth then starts a cycle of creating more food for the tree which can be sent back down to the roots, which allows the roots to expand further and continue the growth cycle.

This increase in growth forces the trunk to quickly thicken. The main difference with this and growing in a pot is that the ground growth has no limitations on how long this cycle can continue.

A tree in the ground will just keep growing until it reaches it genetic potential, where as in a pot this potential is seriously limited by the resources a small pot can provide.

This is why ground growing will produce a large trunk so much faster.

Problems With Growing A Bonsai In the Ground

You need to be able to manage your bonsai growth properly while it is in the ground (I will explain how to manage further down in this article)

Our goal with growing a bonsai in the ground is to allow it to grow freely, without getting too out of control.

Bad Growth Management Of Bonsai In The Ground

If you plant your bonsai tree in the ground and just leave it, it will be fine for a while but after a few seasons it may get out of hand.

There is a risk that the roots will become too thick and too deep.

Your trunk and branching may also get too out of control and become too thick. You may lose taper as everything just thickens too quickly.

Your bonsai tree will basically just become a full size tree and may not be suitable for bonsai after a period of time.

Good Growth Management Of Bonsai In The Ground

If you manage your bonsai trees growth while it is in the ground properly, you can end up with a rapid development of your tree.  

You can end up getting a very thick trunk, with great taper into the primary branches and an excellent root spread. 

By managing the roots and top growth you can make sure that you get these benefits without letting your tree get too out of control and returning back to a full size tree.

What Type Of Bonsai Tree Can You Grow In The Ground?

You can grow any species of bonsai in the ground, so long as it is able to survive in your climate it will be fine.

It can also be at any age and at any stage of its bonsai journey.

Growing Seedlings/ Young Trees In the Ground For Bonsai

Young trees are going to be the best trees to plant in the ground to grow as bonsai and are the most common trees to do this technique on.

They are going to small and probably have really thin trunks. Growing these the ground will let them thicken up far faster than growing them in pots.

 In a number of years you can turn a seedling or a young tree into something with a very powerful trunk and very suitbale for bonsai.

Growing An Established Bonsai In The Ground

You can also plant a developed bonsai in the ground. This isn’t that common, but it does happen.

Usually this is done in a large growing container, but the ground is also used as well. The main goal with this is to increase the trees strength.

Sometimes older bonsai trees that have lived in a small shallow bonsai pot for a long time start to become weak from a lack of resources over the years.

Growing them in the ground will really help it regain their vigour. However, it must be carefully managed to make sure it does not get too out of control or you will lose some of the bonsai development that is already in the tree.

If you just planted it in the ground and left it, it would just become a normal tree again after a period of time. Established bonsai trees are not normally grown for long in the ground. Usually a season or two is enough to get them back to full strength before they are put back into a bonsai pot.

If you are finding this article useful you should also check out my YouTube Channel, I post new video’s every Sunday.

I like to show each of my Bonsai trees journey throughout the year in a sort of time lapse, along with some tips and techniques throughout the video.

How To Plant A Bonsai Tree In The Ground

You can actually plant a tree in the ground at any point in the year. This would involve simply digging a hole, then placing the whole root ball, untouched, into the hole and covering it up.

Although this method will work,  it’s not taking into consideration its long term goals as a bonsai.

If you decide to place a tree into the ground for bonsai, you should treat it like you would any other repotting. I would suggest you wait until spring and place it in the ground as the buds are starting to swell.

I would also loosen the roots and try to organise them and spread them out and potentially give some of them a trim as well. This will set your tree up far better and you will end up with a better root base in the future.

Growing Bonsai In Grow Beds

Growing bonsai in the ground can be as simple as digging straight into the ground, or you can set up a raised grow bed.

You can build these grow beds with planks of wood in same the way that you would see another other raised grow beds in other forms of gardening.

Using a row bed allows you to control the soil that the bonsai tree sits in. As there is nothing at the bottom of the grow bed, the tree can still grow down into the natural soil if it needs to. Grow beds can also make it slightly easier to dig the tree out, as the soil it is in will usually be a higher quality and less compacted.

In Japan you will often see bonsai trees grown in the ground in a mound. Instead of building a grow bed structure to place the soil in, they just mound soil up and place the trees into this mound. It’s the exact same as a grow bed, just without the retaining walls.  

Grow Your bonsai On A Tile In The Ground

A common method of keeping the roots under control while growing a bonsai in the ground is to use a tile.

You place this under the tree and it prevents the roots from growing straight down and getting to strong. The roots hit the tile and have to spread outwards.

Not only does this spreading action stop the roots going down, it will also help to develop a root base that has a wonderful spreading effect, which will be very good looking.

Some people use wooden boards under the tree instead of tiles.

This has the same effect as a tile. However, you can force an even better root spread with the wood by screwing the board to the base of the tree. This gives you even more control over how the roots are grown as you can start to place the small roots where you want on the wooden board before planting.  

How To Manage Bonsai Trees While In The Ground

Bonsai trees planted in the ground need significantly less work than bonsais in pots, but they still need some basic maintenance while they are in the ground to make sure they do not get too out of control.

Pruning A bonsai In The Ground

Pruning of bonsai trees growing in the ground is quite minimal. The goal is usually to thicken the trunk, so the longer you leave the top growth, the quicker your trunk will thicken.  

Pruning Deciduous Bonsai That Are growing In The ground

Some people like to prune everything back after a season or two and then let it fully grow out again. This can help with movement and taper of the trunk and branches. This method can be slower, but the tree will end up with lots of smaller scars, that are more likely to heal with time when using this approach.

Some people just leave the top totally untouched until they want to remove the tree. They then cut it back hard, pretty much to a stump. They then remove this and start building the tree from this stump. This can result in some large scars that may never fully heal. However, carving these wounds can make these trees very interesting.

Pruning Conifers Bonsai That Are growing In The ground

If you are growing conifers, like pines, you need to grow them slightly differently.

You can leave one branch to just go wild and get super long, while trimming the rest of the tree back to develop it.  

This one long branch is called a sacrifice branch as it will be removed at a later point. Its purpose is to grow the thickness of the tree while the rest of the branches develop ramification.

Once this sacrificial branch is removed you are just left with the rest of the smaller branching that you have been developing as bonsai.

Pruning Establish Bonsai Bonsai That Are growing In The ground

If you are planting an established bonsai in the ground, you will need to prune it more often, Allowing all the branches to get too out of control could lead to a loss of ramification and structure.

You would need to decide how much pruning is appropriate based on the individual tree, but I would  suggest it would be pruned more often compared to a young tree that is just being allowed to thicken.

Doing Root Work On Bonsai That Are growing In The ground

In the same way bonsais need repotted and root work done every now and again, bonsai trees that are grown in the ground also need this work. Although we are trying to let the tree grow wild and gain strength, we need to make sure it does not get too out of hand.

We will be digging the tree up at some point and putting it back in a pot, so we need to make sure that this is still possible. By occasionally pruning the roots we will make sure that when we do dig the tree out, it is not too large and out of control.

You don’t need to do this as often as you would with a potted bonsai and the work may not be as extreme, but it is still important to carry this work out.

You should probably do this work every 2 years, potentially every 3 years. It depends on the species and how well it’s grown, but I would not want to wait longer than 3 years or your roots may be way too out of control and large.

It can be argued that doing root work to trees that are growing in the ground can be counterproductive, or it can slow the ground growing process down.

However, I would rather take a little bit longer with my ground growing and end up with a root mass that I can manage. I feel this approach will be faster in the long run. If you let a root mass get too out of control, it can take a long time to get it back to something more usable.     

How To Remove Your Bonsai Tree From The Ground

Once you are happy with the size and health of your bonsai tree you should treat it like it is being repotted, but with the extra care of treating it like a yamadori. Imagine it as sort of in the middle of these two.

(If you are not sure how large to let your tree get before removing it from the ground, you can read more on What Size A Bonsai Should Be)

You need to remove it from the ground in spring as the buds are starting to swell. You can then put it into a training pot.

I wouldn’t work the roots too much and wouldn’t put it immediately into a small shallow bonsai pot.

You should start with a large training pot and slowly over the next couple of seasons start to refine the root ball. You should reacclimatise it to being grown in a pot again.

How Long Should You Grow A Bonsai In the Ground?

The time you need to keep your bonsai tree in the ground is totally dependent on what you’ve started with, your end goals, the species and the environment.

You may find 1 year is enough, you might need 10.

Basically you can keep your tree in the ground for as long as you want and remove it when you are happy with the progress it has made. There is no right or wrong answer, it will just take as long as it needs.

(You can read more about Speeding Up Growing A Bonsai Tree)

Conclusion

Taking the time to grow your bonsai tree in the ground is going to seriously improve your tree and speed up its overall progress to becoming a bonsai.

It is still going to take a long time, but the progress your tree will make, will far outweigh any development it would make only growing in a pot.