Making concrete pots

[Jaboticaba45]

So I had to fix the driveway and there's a few bags left over of concrete. I was thinking of making a large 50+ gallon pot. Problem is the PH is super high...I've read you can soak them to leach the ph out, but it still looks like no matter how much time the ph will still be too high. Any pointers and advice. And has anyone done this before?

[Okvid]

Maybe you can cure the concrete in water and let it sit there for a few months. You should look to the fish and aquarium hobbyists as some people use concrete.

[Oolie]

You could use vapor barrier or similar sealant to create a non permeable barrier between the soil and the pot. Clay might be the best choice.

The cement will always dissolve as long as the soil is in contact with the surface and is wet.

[Ognin525]

Hey ryan we use this plastic to waterproof basements it keeps an air gap between soil and concrete so your walls never have hydro pressure on cracks also keeps it dry. It would work if you lined the walls and bottom of the pots with it. Basically airpot sheets without the holes drilled.

[Jaboticaba45]

Thanks Bill, Okvid, and Oolie
It does give me an idea. Maybe just make a pot from wood then just line it with another material. Probably lighter and easier to move. Although I was going to keep the pots as a semi permanent structure in my greenhouse. If only I had another 100 or so square feet then I'd invest into a dragon fruit trellis.
But anyways the concrete pots that is a very good idea. Just how to drain the water? If everywhere is lined it'll just become waterlogged? I was thinking holes in the side or bottom. Mind my ignorance...I'm new to this lol.

[Plantinyum]

Thanks Bill, Okvid, and Oolie
It does give me an idea. Maybe just make a pot from wood then just line it with another material. Probably lighter and easier to move. Although I was going to keep the pots as a semi permanent structure in my greenhouse. If only I had another 100 or so square feet then I'd invest into a dragon fruit trellis.
But anyways the concrete pots that is a very good idea. Just how to drain the water? If everywhere is lined it'll just become waterlogged? I was thinking holes in the side or bottom. Mind my ignorance...I'm new to this lol.

You should make holes at the bottom of the cement pots, depending on your mold you can have them as a part of the design and not have to drill them everytime.

Hey ryan we use this plastic to waterproof basements it keeps an air gap between soil and concrete so your walls never have hydro pressure on cracks also keeps it dry. It would work if you lined the walls and bottom of the pots with it. Basically airpot sheets without the holes drilled.

I use the same material to make big and whatever the size pots for some plants. I do them round and fix the 2 ends with zip ties. Works very well, the material is durable and can last at least several years.

[Oolie]

It depends on the shape of the pot, but anywhere low is best, including the bottom of the pot. If the shape of the walls do not narrow towards the bottom, holes around the edges of the bottom will be necessary for even drainage.

[Shovel n Seed]

Yeah you would make the drainage holes as part of your form.  Styrofoam works great bc it's easy to remove. Also I'll see if I can get my friend recipe but he combines 3 ingredients to make light weight concrete pots. Big ones too

[Plantinyum]

Yeah you would make the drainage holes as part of your form.  Styrofoam works great bc it's easy to remove. Also I'll see if I can get my friend recipe but he combines 3 ingredients to make light weight concrete pots. Big ones too

i think ive heard about this, i think they add perlite to the mix

[Ognin525]

Plantinyum i made a few air pots too with it , it works good only problem is finding a bottom. Shovel n seeds got a good idea with styrofoam drains iv done that and pressure washed it out or you can use some 1 1/2 - 2 inch pvc . I didnt even think about light weight concrete now i might be trying this too haha .

[Plantinyum]

Plantinyum i made a few air pots too with it , it works good only problem is finding a bottom. Shovel n seeds got a good idea with styrofoam drains iv done that and pressure washed it out or you can use some 1 1/2 - 2 inch pvc . I didnt even think about light weight concrete now i might be trying this too haha .

yes , for a bottom i usually used a piece of the same material, or a nylon of some sorts, it works if you dont need to move the pots too often or at all. However, i find that when the plant roots itself into this pot you dont really need a bottom to it, at this point i just place them on the concreet without a bottom, they are so rooted that no soil comes out when watering.
I think about also doing a concreet pot with this material on the outside, it will make a nice texture to the pot.

For a bottom one could just do a concreete slab, with asquare ,circular or whatever shape he intends the pot to be, then place the vertical part on top of it. That would work well but will be a little tricky if it needs to be moved ,if its a really big one and filled with soil...

[Shovel n Seed]

One part Portland. One part sphagnum peat moss. One part perlite.

That's his recipe and his pots are amazing. He made crazy shapes too

[happyhana]

The bigger and lighter you make them, by adding more perlite and peat, you should begin to add concrete glue and glass fiber for strength. Searching for hypertufa recipes will give you a good jumping off point.

[wagatanga]

Making a concrete pot is a fun and resourceful project! You're right about the pH issue though - fresh concrete can be alkaline, which isn't great for most plants.
But don't sweat it! Leaching is the way to go. Soak the pot thoroughly, let it dry, and repeat. It's a bit of a process, but it helps. Once pH levels drop to a plant-friendly range, you should be good.
If you still have questions or concerns, why not check out https://www.lafayette-concrete.com/? They've got some top-notch resources on everything concrete-related. In the end, the key is patience. It's like brewing the perfect cup of joe, it takes time, but it's worth it in the end.