JTGJr25

I bought a pot a while ago, a shohin sized one ,and it's a nice little pot. The thing is, it is glazed on the inside. I don't plan on putting a tree in it until next year but does anyone know how to remove the glaze from the inside? Is it really that big of a deal to have glaze on the inside? I know it has something to do with moisture not being able to seep into the pot or something like that but couldn't that be beneficial for a small tree?

I could be talking gibberish here, please let me down nicely.


Tom

Ravenna

Hi Tom,

I wouldn't really use a pot with a glaze on the inside. The idea of a clay pot is that the porous inside can absorb some humidty. Glaze is like glass: it won't absorb any humidity and I wouldn't really start trying to remove glaze on the inside but that is just my opinion.

Rick Moquin

To debunk another bonsai myth, high fired bonsai pots (which become vitrified with the firing) do not breath nor accept moisture, whether glazed or not. This includes inside/outside what ever.

Although it is preferable to have the inside glaze free, no harm will come to the tree should you use it. The purpose of an unglazed pot is so the roots will cling to the sides and assist in anchoring the tree nothing more.

That being said, low fired pots e.g terracotta and similar will accept moisture and hence should always be raised off your bonsai bench and inch or so to allow air to circulate as the pot underneath will remain wet and this moisture maintains the tree too moist. Having said that, a tree that likes to remain in heavy moisture like willows and bald cypress etc... it is perfectly ok not to elevate the pot from the bench. As a matter of fact my willow sits in a tray of water and never misses a beat.

I hope this has clarified matters for you and assisted others in debunking this myth.

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JTGJr25

Thankyou Rick for clarifying that. I thought about the roots thing as well. Maybe I can try to scratch the inside and ruff it up a bit so the roots can cling to the inside.

Tom

EDIT: I just hatched an idea, I could place a very large piece of mesh over the drainage hole so the roots could cling to that instead.

Rick Moquin

Tom,

Don't worry about it, just pot the tree in the pot and anchor using wire as per normal. No fuss no muss

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Ravenna

Hi Rick,

I am not sure whether stoneware is really just as a glaze though you do have a point that it will certainly be denser than terracotta.

What I am not convinced about is though your theory about terracotta pots keeping the moisture more. On the contrary: if you have an unglazed terracotta pot it will absorb moisture but also let it evaporate on its outside. So actually a plant will be drier in a terracotta pot than say in a plastic pot or a glazed pot where it risks standing in a "puddle". The danger of a glazed pot hence would be that the roots are more likely to rot in there than in an unglazed terracotta pot. As I said I am not entirely sure whether stoneware is just as impermeable as glaze I would have to double check on that but may be we have some experienced potters here who can tell.. I have read different things on the net so far.

Just my two cents...

Rick Moquin

Ravenna,

I agree with you that terracotta does breath and evaporates, hence the calcium deposits on the surface. However, water under the pot will not, this tidbit I proved to myself. Therefore good air circulation will alleviate this particular problem.

When it comes to the moisture retentiveness of terracotta or low fired pots, although they do breath, they retain more moisture as the pot is like a sponge in the first place.

A lengthy discussion with potters took place some time ago wrt this subject. Where I thought that unglazed pots breathed vice the glazed kind. That is where the myth got debunked and I offered a second de-bunking here, but you are indeed free to draw you own conclusions. A high fired pot becomes vitrified and hence water proof, not 100% but you get my gist.

It is not the pot perse that will retain too much moisture but the substrate the tree is in. Several renown enthusiast grow their trees (in training) in plastic tubs/pots etc... IMO, low fired clay pots are much more conducive to root rot than any other pots available on the market.

In closing, I use the same substrate for all my trees and have come to find out that the terracotta pot's soil retains more moisture comparatively speaking to other containers of similar size.

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Ravenna

Hi Rick,

in some points we agree but I don't really understand your reasoning why you think that you would have less problems with too much moisture a plastic pot or fully glazed pot compared to a clay pot (obviously if all the other conditions are the same, no one denied that an important aspect of drainage is the soil).

JTGJr25

Thanks for the great discussion guys. Even if it does mean it will retain more moisture than usual that is not a bad thing considering it is a small pot, 4" diameter. It should work well I suppose.

Tom

Ashley Barns

The main reason potters do not normally glaze the inside of their pots is simple economics... it costs them. Because the pot you have Tom, is small, the potter probably said .. what the hey I'll do it anyway.

As long as you have a well draining mix it makes no difference if the pot is glazed inside or not.


Ash