Grow Box & Nebari Board - Sealants to Avoid?

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Are there any wood sealants to avoid when treating wood containers that will be in contact with roots? Have you used anything that has caused an adverse reaction in the plant? Or is there a known ‘go-to’ product?

I’ve got some paste wax and varieties of polyurethane in the garage. My inclination is to use the paste wax.

Obviously the intent is to waterproof the wood container for longevity and to avoid rotting.
 
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Just use cedar. I build my grow boxes from cedar picket fence boards, they are like $2 each and last for years
I’d rather just treat the wood than hope that it doesn’t invite disease, warp, etc.

Also, in the future I’d like to try building some higher quality boxes/pots that are more visually appealing using better wood. Those will need to be sealed. Woodworking is my other hobby, but I’ve never played with bonsai projects.

Looking for sealant experience with root exposure.
 

PABonsai

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I used this, though I haven't used the boxes yet. I figure if you use it on your deck your flower beds beside it won't suddenly die. plus due to the rocks we call soil it won't really last inside the box long term anyway. I used this on cedar. Once cured I wouldn't really worry about any product being toxic. Once cured paints and stains are largely inert.
 

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Omono
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I thought everyone just used cedar boards to avoid all of the chemicals. I'd be interested to hear what can be used though, I only build mine from rot and warp resistant wood at the moment but if there's something cheap I can seal with maybe I'll start collecting any old scrap wood
 

Eckhoffw

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Like canoe guy mentioned, I would use oils.
Any oil suitable for butcher block should be a safe bet and add some protection. Still probably not as good as cedar or an exotic wood like ipe - as I believe u generally need to reapply oils.
I just use any old wood, mill it up, make a box and burn it when it rots! 🔥 burn!burn!burn!
 

PABonsai

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I wouldn't use oils mainly because you would have to recoat every few months with the extensive watering we do. Good luck recoating the wettest part (the inside) with a tree in it. Something like butcher block oil would need refreshed several times a month. Honestly I wouldn't worry about it one way or the other. Unless you plan on eating the tree it wouldn't really matter.
 

Tieball

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Pressure treated decking has worked fine for me over the years.
I also use pressure treated wood from the Home Depot. I have for at least 15 years now. I like the Home Depot Cedar Toned wood. Some say it’s not good for roots...they read that on the internet somewhere....but have not actually used it to see results. Internet created fear. I use it...and I have never had a problem throughout the years....and the boxes last a long time. Outdoors all year. No sealer required or desired. The boxes do not attract insects. I use 1x6 and 1x4 Treated. Trees are all healthy. Very healthy. The Treated has lasted much longer than Cedar Wood of the same dimension...much longer. I’ve used Cedar several years ago....and switched to Treated. The Pressure Treated is also very stable and does not warp. I use stainless steel screws.
 

MrWunderful

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Cedar. Or plastic cutting boards. I wouldnt want any sealant or stuff leaching into roots.
 

n8y

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It sounds like you're interested in making fancier grow boxes than I typically do, but I use whatever I can find at the Habitat for Humanity reStore, pallets or construction debris. I'm typically just looking for something that will hold together for a few years.
 

Mellow Mullet

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I have used the "plastic" decking boards and they work out fine and last, seemingly, forever. I also use treated wood, it lasts a long time too. The trouble that I see with sealing the wood is that eventually a crack in the sealer will appear and will allow water to absorb into the wood. Since the rest is sealed, it never dries out and it actually will rot faster that if it was not sealed at all.
 
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Thanks for all the feedback. These ideas echo the brainstorm I had with myself before posting the question. I agree that oils will likely leach, I won’t use oils.

Despite all of the ideas, no one has mentioned personal experience with applying sealants. Chime in if you have.

It seems I may need to try some different things and share them here. My hypothesis is: anything that cures ‘solid’ should work. I’ll likely start with polyurethane.

Are show-quality wooden bonsai pots a thing? I’m yet to see anything more fancy than a grow box.
 

AJL

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How long do you intend keeping your trees in a grow box?- theyre usually only intended as a temporary measure for growing on trees during development and not intended to be used for exhibiting trees!
 
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How long do you intend keeping your trees in a grow box?- theyre usually only intended as a temporary measure for growing on trees during development and not intended to be used for exhibiting trees!
1. I use training pots, but am well aware of the purpose of a grow box vs a bonsai pot. Clearly, I would not be exhibiting a grow box.

2. My original post was more geared towards Nebari boards (clearly for training, not exhibition), which will always be wet and in contact with the roots. I’d rather the wood not be saturated in water touching the roots.
(2a. I have wood laying around and don’t want to buy a plastic cutting board.)

3. I like working with wood, so the next progression in my curiosity is: although it’s not traditional, I wonder if anyone has built nice wood bonsai pots. Not grow boxes, but actual pots. I think a walnut pot with compound cut corners, feet, a beveled or trimmed top edge, with some nice finishing touches would look sharp; stained and polyurethaned. It would obviously be unique. I’d guess a lot of people wouldn’t like it, but it seems interesting and worth some creative exploration.

4. I’m not trying to solve a problem or learn about the uses of grow boxes. I’m just taking a poll for the sake of feeding my artistic day dreams... Thus, who has used sealers on their wood grow boxes/Nebari boards and what are your results? And, has anyone seen an actual wood bonsai pot (that’s not a grow box)?
 
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I found an example of what I was thinking. It’s definitely unique. Kinda neat though. I think I’ll eventually try something similar... cuz why not, the winter is boring.
62240BB3-5976-454F-BA81-E78579E64D02.jpeg
 

Tieball

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3. I like working with wood, so the next progression in my curiosity is: although it’s not traditional, I wonder if anyone has built nice wood bonsai pots. Not grow boxes, but actual pots. I think a walnut pot with compound cut corners, feet, a beveled or trimmed top edge, with some nice finishing touches would look sharp; stained and polyurethaned. It would obviously be unique. I’d guess a lot of people wouldn’t like it, but it seems interesting and worth some creative exploration.
I have thought about doing this too. I just haven’t gotten to far. I have some beautiful Hickory wood I bought for this purpose. It has a very quiet marbled appearance. I also have some imported African woods just for this use. While it’s not traditional...I don’t really care....it’s still my design choice. It is something I will work on. When I’m done....you’ll have to look close that it’s not pottery.
 

Woocash

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3. I like working with wood, so the next progression in my curiosity is: although it’s not traditional, I wonder if anyone has built nice wood bonsai pots. Not grow boxes, but actual pots. I think a walnut pot with compound cut corners, feet, a beveled or trimmed top edge, with some nice finishing touches would look sharp; stained and polyurethaned. It would obviously be unique. I’d guess a lot of people wouldn’t like it, but it seems interesting and worth some creative exploration.
I hadn’t even thought about it but that’s a great idea. I’ve even got some old scraps of teak lying around...hmmm.
 

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