Pots

Kevster

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How many people have actually had pots freeze and break?
I understand when you have a finished tree it would be very important for this not to happen. I just find it very hard to believe this to happen unless it was an ideal condition to cause this problem. Tericota pots absorb lots of water and I have never seen one freeze and break.

I ask this because my fiancée has started making pots. And by no means are they show quality or something I would even brag to friends about yet. But I figured I'd be the good guy that I am and put a few of my trees that are in training into some of her better (unique) work so she feels a bit more accomplished and happy. But I don't want to find tree roots exposed to cold dry air for a long period of time.
 

Alex DeRuiter

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I'll preface this by saying I'm not a potter and I don't know all too much about pottery.

For what it's worth, last year I had a couple terracotta pots break on me last year. They were buried in the ground, but it gets quite cold in Michigan -- enough to break the buried pots. As for pots above ground, I haven't had an issue yet. I do remember hearing that in order to make pots that will survive cold temperatures, they need to be baked at a higher temperature and be less porous...but that's about all I know in this subject. Pjkatich or GastroGnome would be of better assistance. ;)
 

rockm

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"Tericota pots absorb lots of water and I have never seen one freeze and break.
Terra cotta pots DO break--very easily if not all at once, in a couple of years. They flake and dissolve in the face of continued freeze/thaw cycles. They are too porous, allowing water to enter their surfaces and in some cases all the way through the pot wall. Since water expands when it freezes, the clay "explodes" or deep fissures develop in the clay theat eventually cause the clay to slough off in chunks or turn to dust. They are NOT bonsai pots and are too low fired to be of much use. Additionally, expanding frozen bonsai soil can also easily crack terra cotta. They're too delicate for bonsai use.

Purpose-made Bonsai pots constructed by specialist bonsai potters are high-fired up to cone 9, seven at the very least--which is about 2400 degrees F. If your girlfriend is a potter, she will know what that mens--the higher the temp, the tougher the pot generally. The extremely high temps turn the clay into stoneware, whose surface is not permeable to water and exremely durable in freezing conditions. Even some high fired pots can crack in freezing weather, because of flaws, the shape of the pot (pots with incurved rims dont' allow soil to expand upward forcing the pressure to the sides and cracking them).
 

Bob O

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I lost 4 pots to the last winter, 2 had their glaze spall off the pot and the others broke into pieces. We had a roller coaster temperature wise and I believe this contributed to the damage.

Bob O
 

Ang3lfir3

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"Tericota pots absorb lots of water and I have never seen one freeze and break.
Terra cotta pots DO break--very easily if not all at once, in a couple of years. They flake and dissolve in the face of continued freeze/thaw cycles. They are too porous, allowing water to enter their surfaces and in some cases all the way through the pot wall. Since water expands when it freezes, the clay "explodes" or deep fissures develop in the clay theat eventually cause the clay to slough off in chunks or turn to dust. They are NOT bonsai pots and are too low fired to be of much use. Additionally, expanding frozen bonsai soil can also easily crack terra cotta. They're too delicate for bonsai use.

Purpose-made Bonsai pots constructed by specialist bonsai potters are high-fired up to cone 9, seven at the very least--which is about 2400 degrees F. If your girlfriend is a potter, she will know what that mens--the higher the temp, the tougher the pot generally. The extremely high temps turn the clay into stoneware, whose surface is not permeable to water and exremely durable in freezing conditions. Even some high fired pots can crack in freezing weather, because of flaws, the shape of the pot (pots with incurved rims dont' allow soil to expand upward forcing the pressure to the sides and cracking them).

+1 ..... I use terracotta pots for training extremely young trees... the pots are cheap and the azalea pots are shallow .... works great... but i don't expect them to last more than a couple years... if I am lucky....

I would make sure to let your girlfriend know that the pots for bonsai need to be fired to cone 9 or 10 (i think Dale might fire to 11 ) this will effect some of the glaze choices as well I believe...
 

Kevster

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Thanks everyone!
I'm not sure her class will be firing at that temp or let her do it since they fire several piecies at once. Maybe when she gets more advanced.
 

jk_lewis

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Many (too many) inexpensive Chinese pots (usually/often the ones with a glossy blue glaze) will spall anytime temperatures drop in the teens or below -- especially if the pot had been watered the day before.
 

JudyB

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Many (too many) inexpensive Chinese pots (usually/often the ones with a glossy blue glaze) will spall anytime temperatures drop in the teens or below -- especially if the pot had been watered the day before.

Been there had that... Now I take the trees and put them into overwintering pots that are the same shape/size, but stronger than my nicer glazed pots. Even some of the med. priced glazed pots will do this. And I agree that is has a lot to do with water content, and temp fluctuations.
 

Vance Wood

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There are a couple of things you have to remember. Water always wins. Water breaks down every thing given enough time. Water cannot be compressed, it is in essence a liquid solid. When water freezes it expands.


The softer the pot in its porosity the more it will absorb water. The constant freezing and thawing of absorbed water will cause the structure of the pot to break down. The freezing of traped water in the soil mass, if there is enough, will crack and then break pots that contain overyly wet soils. Pots that are fired to what is called a Cone Ten are less likely to be destroyed by winter weather.
 

Klytus

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Even these 10 year guarantee glazed stonewear pots will fly apart,an inturned rim and recent repotting combined with expansive ice will do it.
 

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