An outward flare as the pot trends upward, or a pot whose mouth is bigger than the neck, allows for frost expansion. In areas that freeze where the pots are left on the bench, broken pots are common from frost heave, that is, the moisture expands and there is no room for the ice to move the soil and it breaks the rim. Another consideration for frostproof pots is that the firing temperature has to be hot enough to completely vitrify the clay or it may be too porous for cold weathering.
I am a hand building potter who knew NOTHING about bonsai pots. I got a commission to make some but I was winging it. Your videos have been extremely helpful. I'm hoping to continue making them even after the commission now that I know the purpose of the holes, how they are used, etc. It's definitely a learning experience! Thanks for your help and great explanations.
Your always ,correct, if you look at the Japanese training pots they have glazed rims, I think it so moss won't grow on the edge, so they don't slip from your hand ,when you pick the pot up
What a nice video! So many professionals show their best pieces to show off and how to do it…you do the opposite and show your beginnings and it’s learning mistakes…Thank you!!!
Nice critique of those different styes of bonsai pot Eric. I agree with what you pointed out with each one, I also find it especially tricky to add a rim to the inside top of pots so always add the rim to the outside as you point out this makes it difficult to get the tree out when repotting. You mentioned glazing on the inside of a bonsai pot and I believe the reason we don't do it is because the tree roots seem to 'cling' better to the unglazed rough texture of the clay (I use a crank clay body). I did see an explanation years ago so not sure how true this is, however I never glaze the inside of my pots - unless it a Suiban!
I bought some plasterboard joining tape it's 2 inch by 50 meters it's a mesh type and it's great to use for the drainage hole it's slightly adhesive and it stays put.tfs your technique. When I use a non bonsai I use adhesive raised plastic dots
I took a pottery class in 2011 so I could make bonsai pots. This would have been great to have before I started. I thought I was going to love throwing pots on the wheel but found I loved hand building. I want to get back into it.
With regards to the square central hole, if you put the staple diagonally to begin with there would be no ability for the screen to rotate at all, so there'd be less potential for movement even than a round hole. Perhaps that was your original thought in making the holes square?
Maybe. And yes you are correct. But round works. Perhaps I even thought that a square hole would drain better because the surface tension of water would be less at the corner. I'm not sure what I was thinking in 2006.🙈. In retrospect I see no benefit, but I am not omnipotent and all-seeing.👀
Eric Really nice video, your comments are spot on. The initial reason pots are not glazed on the inside (per Michael Ryan Bell) is that when glazes had minerals such as lead in them, they were toxic to the trees. So no part of the soil was allowed to touch the glazed area as it could leach and poison the trees. Not glazing the insides is now just traditional.
Holy snikes how much for the skull pot that blew my mind I've never seen anything like it I'm currently making my own concrete pots but nothing on the level of what you have especially that's skull pot just amazing and thank you for the advice appreciate informative videos like this
John - if you like that, check out Thor Holvila's web store: www.holvilabonsaipot.com/shop-1?page=2 email me if you want the one I have and we can discuss.
@@Bonsaify I looked at those parts and you're not kidding some incredibly stunning pots I looked for your email address and I'm kind of new to all this only really use RU-vid and email
My question: “Bonsai pots aren’t glazed on the inside” curious if we don’t know the horticultural reasons- is the reason “just because” perhaps? Perhaps there isn’t much of a reason that would be a detriment to the trees, as we see porcelain has been used, folks have used fully glazed pots, and the textural coefficient doesn’t stop other potted plants from growing well. Perhaps the pervasive element of * no glaze on the inside* actually comes from a tradition of economy or horticultural myths of roots being happier grabbing a more rough surface. I’d love to know your thoughts as I had just had this convo today with folks and was reading about it on BNut.
@@PIT-EKA thanks for the response and I love your work btw- in that case I may continue to glaze the inside of my pots until it’s no longer within my means.
I thought the absence of glaze on the inside and both sides of the pot bottom help with evaporation of water, so the pot can breathe a bit like a terracotta pot.
@@Sylvicolus actually pots used for bonsai or outdoor use other than terra cotta or such are vitrified, making them mostly impervious to water, so they don’t do the “breathing” that terra cotta or earthenware does.
@@Sylvicolus terracotta is a low fired clay with a high absorption rate. Mid and high fired clay when vitrified have a very low absorption rate which limits water entering the fired clay. This is why they are able to survive repeated freeze and thaw cycles.
Excellent presentation of bonsai pots. Interesting, attractive, with lots of details and pertinent observations. And I think not everything has been said yet. This could be only part one of a larger presentation. Have you thought of continuing it? You could also talk about the suitability of the tree to the pot, how to choose the right pot for a particular tree. There is so much to say about bonsai pots, and you are clearly both experienced and gifted in teaching. Well done!
Thanks for your comment. I could do more videos along these lines, but matching the pot to the tree is too large a topic to cover in one sitting. It's better to discuss in the context of a specific tree with examples. Then another tree... Then another.
I can’t find a video that I think was yours . You mentioned in passing about a technique of only removing the top inch or 2 of soil. But I can’t remember what you called that . Excellent videos 👍🏻
Fall soil cleanup is called Soji, you can check the pomegranate video at about the 2:45-3:30 mark. I may have mentioned it in the black pine fall video also...
I think the reason not to glaze the inside of pots is that it's not necessary and would be a waste of glaze. I don't see that it makes a difference for the plants. People grow bonsai in plastic pots with no problems. The surface of the inside makes no big difference for the plant.
Re: problem with square holes. A square hole makes for 4 stress risers at the corners.........just like the perferations in paper. They cause both a concentration and a weakness at those points.
Thank you so much for sharing these tips. I have made few bonsai pots and I am always wondering about the thickness of the walls . What should be the ideal thickness of the slab ? Should the thickness of the walls be same for the thrown pots and slab pots?
The thickness is generally determined by a balance between structural strength and utility. In larger pots you have a thicker clay throughout. In smaller pots you don't need as much strength so you want to prioritize the volume of soil. Certain areas of pots are normally slightly thicker - the junction of the wall and bottom, and the rim for example. I don't think there is a difference between round and other shapes. You should study existing pots and potters for more detailed information.
Hi Eric, I've been making pots for 5 or 6 years . I have always added lugs about halfway down on the inside of taller pots for tie wire, cascade, semi cascade etc. Have you seen or heard of anyone else doing this? I'm mainly looking for any good reason not to.. seems like a good idea to me.. please give me any insight on any pros or cons you can see in doing it this way.. thanks Lyle
There are problems with tall pots and tie wires. But I don't imagine lugs on the inside would be the best solution, as Anders said, it will make it harder to take the tree out at repotting.
Thanks for the great info. Im a potter and I want to make myself a bonsai pot. What clay do you use for outdoor use to avoid freeze/ thaw cracking? Thanks!
I'm not an expert in this because I live in San Francisco...lol. But I believe it is the firing temperature more than the clay. (although the two are obviously related.). I think Cone 6 is the recommended minimum firing for vitrified stoneware. So avoid terra cotta type stuff and go for a Cone 6, 8 or 10 clay. I use Laguna "Dark" locally - but clay is a regional product for the most part.
12:20 - "Too many holes creating additional labour of putting drainage screens" Why not use 1 large sheet of drainage screen ? Japanese bonsai nurseries use it. Herons bonsai nursery, UK uses it too. Its a problem only if one wants individual screens for each hole. But why do it that way ? What difference does it make to trees whether it is 1 large screen or multiple small screens ?
12:31 - "They are not really creating any benefit for the plant" If this was true, then whats the need for 2 medium sized holes or 1 large hole ? Just 1 medium sized hole should be fine. The obvious benefit of this perforated pot floor is better drainage & aeration. Most bonsai pots lack this & hence, its a common practice to put larger substrate particles at the bottom. Even when the pot is kept tilted, a common practice, its drainage will be far superior to a 1 hole pot, which is guaranteed to accumulate excess water. So i find no merit in your criticism. Your teacher Boon uses pumice as bottom drainage layer (search "deciduous training bonsai boon" on youtube). Regardless, i hope your complaint of having to cover all drainage holes is consistently applied at ALL pots (nursery & bonsai) having more than 1 medium sized hole. Even unused large wire holes count bcos they too need screens. Google "Repotting and Rootpruning Bonsai - Part II bonsai4me" to see a pot with many such holes. I hope you will call this too a bad design for the sake of consistency of your criticism. Many European bonsai potters have eliminated the need for drainage screens completely by having a perforated floor of tiny holes, which i feel is a superior design compared to pots with 1-2 holes. On youtube, search for "martin englert bonsai potter" to see such bonsai pots. He is a German potter. Also, image search "Pötscher Walter bonsaischalen walu" & see pots with drainage slits instead of holes and grooves to guide roots to the holes. From the search result of images, choose the one from Bonsai Schalen. On Bing search engine (not google), do an image search for "drilling extra drainage holes in bonsai pot" to see Michael Hagedorn (blue dress, brown pot) drilling big extra holes. He is doing this bcos he was unhappy with the drainage & aeration from 1 large hole & needed 3 more. Many bonsai artists, including experts, often partly bury the bonsai pot in soil, for roots to escape out and get extra growth. The escaping roots are sacrificial and a perforated floor or pot with multiple drainage holes easily allows that, while pots with 1-2 holes easily lose drainage when multiple roots escape out through 1-2 holes & block it. Google "Incredible 388-Year-Old Bonsai Tree Survived Hiroshima Blast mymodernmet" and see 3rd pic from top - a bonsai pot buried in substrate.
Great video! Very informative, still I have some questions. With what type of clay i should make a bonsai pot? Bonsai pot has to absorb water so has to be made with earthenware clay or should be make with stoneware clay what is high fired clay so it doesn't absorb water?
Hi - most bonsai pots are stoneware, the porosity is not important to the plant. TBH, I'm not sure it's ever been shown that terra cotta has some benefit over plastic. If anyone has actual evidence, LMK. You don't want the pot to absorb water because it can then break in a frost. Generally, the clay body is important for traditional pots, and a dark reddish brown or purple-brown clay is the most prized. I would suggest you study the IG profile for Tiberio Gracco who is an Italian bonsai potter who sources his own clays. (rather than manufactured clays.)
@@BonsaifySome of the most highly regarded early to mid 20th Japanese bonsai potters have used quite a bit of white clay. Heian Tofukuji, Heian Kouzan, and Tsukinowa Yusen are prime examples. I've found that white clays tend to give a visual pop to bright and glossy glazes. For unglazed pots, I still prefer the browns, reds, and purples.
2:14 ok but: Who the hell turns a tree around in a pot like this?? No one!!! So thats why i never fix trainage screens in a pot... Cause no one ever move it anyway
