What size nursery pot to use? Rule of thumb?

[geargarcon]

So I’ve seen plenty of posts regarding how to decide what size bonsai pot.

I’ve also found write ups on nursery posts warning of overpotting and water draining out too quickly or under potting and restricting a plant during the development phase.

I got some trade gallon nursery pots that I think will be good for some of my plants but are probably too big for others. Is there a rule of thumb to follow for nursery pot size during development phase?

(yes this is living outside. Just brought in for easy picture. It is currently in a 4.5” wide by 5.25” deep nursery pot, but plan on slip potting into the white pot which is 6.3”x6.3”)

 

[ShadyStump]

As a rule for growing out, go big, but shallow where possible. Many species, as soon as they start running out of room in the pot will just stop growing again, defeating the purpose. But don't use the entire height of the pot, or even just cut it down some so you're only using the bottom portion of it. This is to help keep the roots shallow so you're getting rid of less of them when you finally move to a bonsai pot.

Drainage and other water management issues are essentially the same game as usual: soil composition and watering practices. A more organic mix to your substrate is generally ok for growing out, but you still want it to drain well. That means don't skimp on the inorganic aggregate, and not so much clay like akadama or the like.

Tell us about the tree, and update your location in your profile, and maybe someone will have something more specific for you.

 

[geargarcon]

As a rule for growing out, go big, but shallow where possible. Many species, as soon as they start running out of room in the pot will just stop growing again, defeating the purpose. But don't use the entire height of the pot, or even just cut it down some so you're only using the bottom portion of it. This is to help keep the roots shallow so you're getting rid of less of them when you finally move to a bonsai pot.

Drainage and other water management issues are essentially the same game as usual: soil composition and watering practices. A more organic mix to your substrate is generally ok for growing out, but you still want it to drain well. That means don't skimp on the inorganic aggregate, and not so much clay like akadama or the like.

Tell us about the tree, and update your location in your profile, and maybe someone will have something more specific for you.

Thanks for your reply!
Sorry, I though I updated my location in my profile. I’m in zone 9a. Plants are:
Burtt-davyi
Microcarpa
Benjamina
Green Mound
Portulacara Afra
Fukien Tea
Chinese Elm

soils will be a very dry mostly inorganic mix for the jades. Something a bit more moisture retentive for the others. Planning on putting 1” gravel draining later in the bottom of each pot.

I found 6” wide pots ranging from:
- 6” tall
- 5” tall
- 4” tall

I opted for the 6” tall pots

 

[Tums]

Drainage layer doesn't do anything for drainage because water doesn't like to move between the different mediums. Just use one kind of soil all the way down.

Gallon could be good to start but I would expect a ficus or elm to fill them up within a season outdoors. Maybe an Anderson flat after that?

 

[QuantumSparky]

Drainage layer doesn't do anything for drainage because water doesn't like to move between the different mediums. Just use one kind of soil all the way down.

So is a "coarse drainage layer" at the bottom, actually worse than just having the same soil type all the way down? I have been doing a drainage layer of rock just because I ran out of mesh and all my pots have holes too large for any type of bonsai soil.

 

[Tums]

So is a "coarse drainage layer" at the bottom, actually worse than just having the same soil type all the way down? I have been doing a drainage layer of rock just because I ran out of mesh and all my pots have holes too large for any type of bonsai soil.

If your bonsai soil is coarse enough that no/little extra perched water is retained, then it doesn't practically make a difference.

Otherwise with a drainage layer of a different particle size, you're just bringing the perched/saturated water level higher in the pot. So it's a worse problem with typical organic potting soil that retains more water.

 

[ShadyStump]

So is a "coarse drainage layer" at the bottom, actually worse than just having the same soil type all the way down? I have been doing a drainage layer of rock just because I ran out of mesh and all my pots have holes too large for any type of bonsai soil.

This is pretty much the only reason I ever do anything like a drainage layer, just to keep smaller particles in place.

Though, if you don't want to cut a nursey pot down to make it more shallow, you could use a thick drainage layer in the bottom of very coarse material- like full on rocks, not gravel- to essentially raise the water and soil level to the top of the pot.

 

[cornfed]

Personally, and I'm not even to my first bonsai anniversary so take this with a grain of salt, I'm going to treat development trees as if I were a nurseryman, meaning slipping up from one to five gallon pots in 60-80% composted pine bark and grit and using air-pruning pots.

The organic soil will hold extra fertilizer and water. The air pruning pots will help to develop a fibrous, non-circling root system. Pump as much energy as possible into that first couple inches of trunk to get it thick as possible as quickly as possible.

This is my theory though ... I'm new to this.

 

[Tums]

Personally, and I'm not even to my first bonsai anniversary so take this with a grain of salt, I'm going to treat development trees as if I were a nurseryman, meaning slipping up from one to five gallon pots in 60-80% composted pine bark and grit and using air-pruning pots.

The organic soil will hold extra fertilizer and water. The air pruning pots will help to develop a fibrous, non-circling root system. Pump as much energy as possible into that first couple inches of trunk to get it thick as possible as quickly as possible.

This is my theory though ... I'm new to this.

Just gotta make sure you have some closely spaced nodes at the bottom of the trunk for the eventual cutback?

 

[cornfed]

I don't think you need to worry about nodes for a trunk chop, but I could be wrong. Chop it low, grow a new leader and wire it up for taper.

The tree in my head for this thought experiment is a deciduous tree.

If the goal is thickening the trunk, how does restricting pot size at all help?

Edit: If you want to know why the drainage layer raises the water table, check out this awesome resource on the Nut: https://www.bonsainut.com/resources/introductory-soil-physics.29/

 

[geargarcon]

Drainage layer doesn't do anything for drainage because water doesn't like to move between the different mediums. Just use one kind of soil all the way down.

Gallon could be good to start but I would expect a ficus or elm to fill them up within a season outdoors. Maybe an Anderson flat after that?

Great! This is primarily what I’m looking for, just something to let them grow in for the next year.

though I’m interested in the turn this post has taken regarding drainage layers!

 

[ShadyStump]

Great! This is primarily what I’m looking for, just something to let them grow in for the next year.

though I’m interested in the turn this post has taken regarding drainage layers!

Read that resource @cornfed posted. It's made all the difference in the world for me. It's long, but well worth it.
It explains how "drainage layers" actually impact water holding in you substrate.

 

[canoeguide]

Though, if you don't want to cut a nursey pot down to make it more shallow, you could use a thick drainage layer in the bottom of very coarse material- like full on rocks, not gravel- to essentially raise the water and soil level to the top of the pot.

I've done this for cascades that I'm growing in nursery cans. Big river rocks in the bottom 1/2 of the pot also adds a lot of weight to keep a heavy or long cascade from tipping over.

 

[leatherback]

though I’m interested in the turn this post has taken regarding drainage layers!

Basically, do not use them. I do the same as posted before: If I use nusery opts, there are many holes. And I chuck a handfull of coars pumic in there just to block the finer substrate from falling through. But normally the whole pot is universally sized.

I'm going to treat development trees as if I were a nurseryman, meaning slipping up from one to five gallon pots

yup, for maximum growth that is the way to go. These guys know what they do when they want to reach big fat trees as past as possible.. However..

make sure you have some closely spaced nodes at the bottom of the trunk

This is one concern. I know many will say, you will cut most of it off. However, when I build a truinkline, I want as many buds on there as possible. Later, when building the bonsai you will be happy with many options to grow branches.

Also, slow growing a trunk will give added value to the tree. Less scarring, more subtle bark, denser wood. etcetc. There is a reason why the best bonsai take half a century to get from cutting to first bonsai container. Fast trunks are not usually the best trunks. To be fair, I do both. I ground grow for fast fat trunks. And I have a bunch of trees I am growing slow, in marginally oversized containers. As the ones in the container start to mature, still thinnish trunks, I see some benefits. Enjoy the journey and you are never waiting to arrive.

 

[geargarcon]

Drainage layer doesn't do anything for drainage because water doesn't like to move between the different mediums. Just use one kind of soil all the way down.

Gallon could be good to start but I would expect a ficus or elm to fill them up within a season outdoors. Maybe an Anderson flat after that?

your suggestion of an Anderson flat has me thinking of just a large ” training pot “ instead is a nursery pot. A 9” training pot has the same volume as a 6” nursery pot, only it is wide and shallow

 

[Potawatomi13]

Rule of thumb: Do not drop pot on thumb!

 

[Potawatomi13]

So I’ve seen plenty of posts regarding how to decide what size bonsai pot.

I’ve also found write ups on nursery posts warning of overpotting and water draining out too quickly or under potting and restricting a plant during the development phase.

I got some trade gallon nursery pots that I think will be good for some of my plants but are probably too big for others. Is there a rule of thumb to follow for nursery pot size during development phase?

(yes this is living outside. Just brought in for easy picture. It is currently in a 4.5” wide by 5.25” deep nursery pot, but plan on slip potting into the white pot which is 6.3”x6.3”)

Michael explains this very well in his book Bonsai Heresies.

 

[Shibui]

I don't think you need to worry about nodes for a trunk chop, but I could be wrong. Chop it low, grow a new leader and wire it up for taper.

This depends on the species.
Most trees will only bud where there were originally leaf nodes. You can see this when a trident is chopped and the new shoots develop in opposite pairs. A tree that started out as a seedling in shade with leaves far apart will have less budding options when chopped.
Some trees that have been lifted so part of what was once a root now forms the lower trunk may not have viable buds in that section and may fail to shoot after a chop. Physical damage can remove potential sites for nodes (some root stocks are disbudded so they won't shoot from below the graft)
For most species there will be enough potential growth nodes to make decent new growth for most purposes. If you consider small seedlings the leaves are usually quite close together so most trunks will produce some shoots after a chop.
A few species can produce new buds from cambium. Chinese elms are one that is noted for this. After a chop, Masses of new buds appear from the exposed cambium around the chop which means you can chop anywhere and still get good buds.

I'm not sure that there is a rule of thumb for pot size. Production nurseries tend to pot plants on into one size larger pots whenever they appear to need it or when growth slows. Slip potting can be done any time so there' no need to have a definitive pot size at the start of the year.
I guess picking a pot size will come from experience but there's a fair bit of latitude with most living things so exact measurements is not critical. Just take a good guess at a good size and see what happens.

 

[Mikecheck123]

As a rule for growing out, go big, but shallow where possible.

Wut??

This is exactly the opposite of what commercial nurseries do: small and tall.

 

[sorce]

The only thing good for nursery pots is stuff you are growing out to later layer new roots on.

One of the largest F-U's in bonsai is correcting roots that were grown in nursery pots.

One of the most important rules, one of the only that should always be followed, is "Roots First". It's important because this is the beginning of your design and the beginning of your horticultural endeavor. It is the foundation on which everything is built.

Imagine if when we built a house, we poured like 3/4 of the foundation. Then before the walls go up, we remove some of the foundation just to replace it. Then before the electrician comes in, we tear out more of the foundation and repour it. Then before the plumber comes in, same. By the time the painter came, the house would be wobbly.

The problem with nursery pots, is the design promotes roots that grow in positions where feeder roots almost always get near fully removed when trying to fit it into a bonsai pot.

Using airpruning baskets for early training makes for excellent control of visible surface root growth and a matte of feeder roots that almost can't run and ruin design. This matte of feeders is the foundation on which everything else should be grown, because it can be repotted with the least disturbance to it's usefulness.

...

There is more to "drainage layers" than water.

.

Sorce