What pots are frost-proof


Over the years I have bought mostly American Stoneware and have never really had any problems even so my whole collectin is frozen solid for months every year however some of the Japanese and Chinese pots I have bought have de-laminated and eventually fell apart. When buying foreign made pots how does one know if they can sustain freezing. I am to the point where I am afraid of buying any Japanese and Chinese pots.

(Jonas Dupuich) #2

Wow, that sounds cold! Can you say more about how the pots de-laminate or provide a photo of the damage you’re talking about?

Am also curious if you’re using new pots or old pots (e.g. older than 20 years), glazed or unglazed pots, expensive (> $200) or inexpensive pots.

(gastrognome) #3

Frost proof is a bit of a misnomer anyway. Stoneware can still break if there is too much water in the rootball and it freezes.
All stoneware means is that it won’t break because of water absorbed into the clay body.
That being said, most high quality Japanese pots are stoneware. Cheap containers, wherever they are made, will fall apart for a variety of reasons frost just one of them.
Jonas, she means that the glaze stRts to separate from body I think. This happens Quickly In freezing climates but eventually happens everywhere


My understanding is Japanese, Chinese and Korean bonsai pots are not marketed with the info as to whether they are stoneware or not–just buying,“high quality” is a bit amorphous. When I inquire with the dealer I get," I think so" or “they should be” or “Oh yah, for sure”. Europeans and US potters are clear about whether their pots are vitreous (stoneware-cone 10). I am just wondering is there a way to determine if Japanese, Chinese and Korean bonsai pots are actually stoneware.


I have no pics of degrading pots because I tossed them some time ago and gave up on Japanese pots. It usually goes first there is some shedding of glaze, then cracks, then wholesale de-lamination–its totally because they are not vitreous (stoneware-cone 10). I am just wondering is there a way to determine if Japanese, Chinese and Korean bonsai pots are actually stoneware. Are all Tokoname stoneware? Are all Houtoku stoneware?

(Leo Schordje) #6

Im in the frozen north only a hundred miles south and a couple hundred miles east of Crust, he.is in Duluth, Im just south of Milwaukee. Picture is of the kind of frost damage I have sometimes. Pot is YiXing and felt like it was quality.

(Jonas Dupuich) #7

Thanks, @LeoSchordje and @crust for the info. I don’t know how to tell if a pot is stoneware or not - maybe someone else can help with that bit. As @gastrognome mentioned, it’s common for cheaper pots to fall apart for a number of reasons.

My understanding is that this isn’t a common problem in the nurseries I’ve visited in Japan. That could be because the trees/pots are better protected in winter or because the pot quality is high enough to withstand some cold.

(gastrognome) #8

Well, here’s something we can out of the way real quick. The words Tokoname and Yixing are not synonymous with quality in any way shape or form.
It’s Yixing? What kiln?
It’s Tokoname? Which kiln or artist?
The answers to these questions will tell you if it is frost resistant.
Saying a container is Tokoname or Yixing means absolutely nothing. It’s like saying it was made in Ohio. That doesn’t tell you much. And nothing about quality. Is it a Cochoy? Or an Iker? Or something from a hobby potter who fires to cone 6?
Incidentally, allowing your trees to stay heavily frozen isn’t something the Japanese or great artists I’ve spent time with up north do. There are few antiques that should be treated such, and it’s pointless for the trees anyway. Once the reach the minimum threshold of cold days they will stay dormant until they reach the minimum warm days. Which is around 21. A cold basement should be fine. Cheap containers from anywhere are not frost proof. Period. High quality stuff is(given a few notable examples like Bushuan and a couple guys who specialize in Satsuki containers).

(gastrognome) #9

Oh and one other thing. The only way to tell if a container is stoneware without knowing the artist and his wares is in person.
A very light tap with a tuning fork and the sound of Stoneware is unmistakable. As is the sound of true porcelain.


Ahh, I figured I would get a blast eventually and being I don’t know any Japanese potters personally, or their modes, I guess I have to avoid Japanese-ware unless I can personally see if it “rings”, which rules out internet purchases. I actually have little interest in imported pots anyway but I am attracted to a few in an online auction forum and invariably they are mostly Japanese–so I worry. I had hoped there was a better guide than just "cheapies are not frostproof ", which really is not true because I scored a Chinese 22 inch oval for $155.00 that is very thick-walled and rings like a bell–the owner just wanted to get rid of it–it is perfect for me.

As to frozen trees: I live in the USA in zone 3 and have over a hundred natives, many large or on large stones. They are frozen from around Mid November to April–they are frozen solid right now in a dedicated storage facility which is kept in the twenties most of that time–right now it is 32 degrees in there despite our recent warm spell. In my climate, if you want to grow your trees outside and not shuffle them around, the very best is to keep the COLD and dormant as long as possible. Last frost around here is around May 20th.

Thanks for your help.

(Leo Schordje) #11

Like Crust, I’m growing in zone 5b, and grow many natives that are hardy to zone 4 or even zone 3. My space that stays above 25 F is limited, all larger plants stay outside, under the benches. I guess when a tree is ready for a fine pot, it will need to be protected better. Right now not a serious problem, most of my stuff is still in plastic or mica pots.

(Sely) #12

Stoneware… interesting subject. Most mold forms are solid forms. When building a slab construction pot all the pieces are separate which tend so to make the joints weak and some decorative pieces as well, including the footing and lip. Most porous pots will Crack or a piece of stoneware that not completely fired to it’s desired cone can be porous because it still remain in the bisc firing stage. Stoneware should not absorb water. It’s the water that’s in the terracotta pots itself that freezes and expands to crack the pot.

(Zack A Clayton) #13

I suppose one answer would be to get a pot you don’t mind losing that is the same size as the pot you want to display in. Then only use that good pot for display. I understand that is what they do in Japan to protect their old valuable pots from the rigors of day to day life. It is a luxury I don’t see often in the US, but since you should be not be keeping the trees in a show ready state between display to allow rest and recuperation, why tempt fate by keeping them in your best pots?