check out the hypertufa forum. Hypertufa is lighter, and less expensive.

I mean, the only thing I can say is that most of the tutorials I've seen for cement planters don't include drainage holes, but I can imagine making a mold with one wouldn't be too difficult

The tutorial I found said to use a dowel for a drainage hole. I don't really know what that is but I will figure it out.

I found this one on Pinterest and I like the size idea of this one.
http://mypatternoflife.com/2012/10/02/concrete-planter-diy/

Then there is a how to from Quickcrete
http://www.quikrete.com/PDFs/Projects/CastConcretePlanters.pdf

Besides - if we can drill a hole in clay pots why not concrete?

What will you grow in them? Would you want to haul them in for winter and back out for summer- even if hypertufa? Or would you keep the plants in seperate pots? Also keep in mind that the pH will be quite high (alkaline) for several weeks until the weather leaches the lye/lime out.

tj

hypertufa.. is just a system of mixing in.. lighter materials...so you dont need a fork lift.. to move your pots around ..

it is usually something like perlite.. which is little Styrofoam pellets ...

you seems to be ignoring this suggestion ... or at least.. not acknowledging it ...

ALL PLANTERS... need a drain hole ... unless you want to grow bog plants in them ... not many other things.. like to grow in standing.. stagnant water ...

see link below ...

ken

Here is a link that might be useful: link

Ken - I know I need a drainage hole. I only grow succulents and herbs.

TJ- I appreciate your comment about the ph. Maybe it would be best for me to make them towards the end of winter and leave them outside for a few weeks before planting anything in them. Do you think that would solve the ph issue?

I am not sure yet about the hypertufa. I live in Iowa and it gets really windy here. Even with clay pots I have to move them to the corner of my balcony when it gets too windy because I fear they will fall over. If hypertufa is something I would mix myself I wouldn't want them to be too light. But I will figure that out. I have an apartment and my plants live on the balcony during the warm months, and come inside when it gets too cold. Although it may be nice if they aren't too heavy, I am not afraid of a little heavy lifting. My other hobby is actually powerlifting so I am fairly strong. But I will look into the hypertufa. If it is cheaper and a bit lighter that would be nice for any larger pots I make.

Thank you all for your input and suggestions.

Also, TJ, I plan to pot most plants separately. Part of my motivation of switching to square/rectangular pots is to fit more of them on my shelf. I keep my hobby limited to one self at this point. I live in an apartment and there is really only one spot for them to get good sun, so my collection is restricted to a specific area.

This photo was from the end of summer. I have added a few more plants since then. A TG cactus, some aloe vera pups, and a topsy turvy (I think that is it!). The photo also shows where they get moved if we are going to get several days of rain. However, I have switched most of my plants to gritty mix, and the remaining ones will be switched in the spring. So, hopefully I won't have to worry about that this summer.

I found this little how to on the lowes website. I think I may try this. But I need to find square molds. I might just have to make the molds somehow... or maybe I can find plastic storage boxes that'll do the trick.

http://www.lowes.com/creative-ideas/woodworking-and-crafts/make-hypertufa-pots/project

Deva-
A dowel is just a piece of wood with a circular cross-section; they come in different diameters. You can get a piece of dowel at any hardware or lumber store. You probably want one with about a 1" diameter...or you could just use a stick that you find on the ground! They are simply suggesting that you put a short piece of dowel in the bottom part of the mold so that when everything dries you can pull out the dowel and have a drainage hole.

Thanks kudzu! I figured it was something like that I just haven't used one before. But it sound like you can drill a hole in the hypertufa. I wonder which way would be easier... probably using a dowel...

Deva-
I understand hypertufa is fairly easy to work or drill. However, if you don't have a fat drill bit to make a large hole, the dowel idea may be easier. I'm not an expert on hypertufa, but I understand it is something that is fairly sturdy. However, it doesn't have near the strength of concrete, and if they are big and you are planning on moving these containers inside and back outside annually you may want to go with concrete even though it is quite a bit heavier. I suspect that if you keep moving larger hypertufa containers around they are more likely to crack apart. Whether you use concrete or hypertufa, some sort of reinforcement is recommended (chicken wire in concrete, fiberglass in hypertufa).

A dowel wood be better. If you're making a pot, not having a hole at all is easier than making one when the pot's material has already set.

Hypertufa slab with a shallow depression - sempervivum. Hypertufa can be very easy to drill, depending on how it's made. It's setting on top of a (future) bonsai collected from the wild and over-wintering in the garage.
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Hypertufa trough with dwarf conifers
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In process of putting together mixed containers - small trough in foreground
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Another shallow trough on right
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Hypertufa is easy to make, can be half the weight of concrete, lasts indefinitely. For really neat texture, add small pasta shapes to the mix. When the pasta breaks down, its shape remains as an impression. For fast weathering (to eliminate high pH issues) don't make a drain hole & fill the trough/pot with vinegar & water - or leave it out over winter like you mentioned. Let it cure slowly by keeping it moist or letting it cure in a sealed garbage bag - much stronger. Hypertufa makes excellent pots because they can be made gas permeable. Papercrete is another good way to make really neat, rustic looking pots.

Al

Don't waste your time with concrete from the hardware store. It is overkill for the scale of container you are talking about and weighs a ton. If you want something easy, use bagged mortar mix and add alkali resistant glass fibers which you can get online. That will make a decent glass fiber reinforced concrete (GFRC). It will be weighty but strong. You could add perlite to that to decreade the weight if you want. That will negatively impact strength but at this scale, that should not be too much of a problem.

The most important thing to remember when working with concrete is that water is both your friend and enemy. You need water to get the reaction going and to cure properly, but too mich water will make the resulting concrete very very weak. Your best bet it to only get the mortar mix about as wet as damp sand and pack it forcefully into the form. If you can pour it, you have added way too much water for this application (or added a high range water reducer but that is a whole other discussion). It will harden up relatively quickly. I usually let it sit overnight and then remove the form, very carefully. The concrete is very fragile at this point. Then I put the pot in a trash bag and store it someplace for a month. It takes about a month in a humid environment for concrete to cure completely. Do not let it dry out at all during this time.

It seems that the addition of sphagnum peat in the hypertufa recipes helps to neutralize the pH. Moss and algae seems to establish more quickly on those than on bagged concrete. That is however conjecture. I haven't had any problems with pH and concrete planters.

If your intention is to make efficient use of the limited space on those shelves, concrete may not be the way to go. What you save by making the containers square, you lose by having to make the walls quite thick to make up for the lack of tensile strength in concrete. Glass fibers will go a long way in ammeliorating that though.

Thanks for your input. Al - you have some really beautiful containers there.

nil13 - I was just wondering if making these would defeat my purpose of saving space. I was looking at those that are already made and it appears that the walls of the hypertufa are a bit thick. Is that just the nature of this media? Do I need the walls to be that thick? If so I may need to rethink this whole thing! ugh! I already started saving containers to use as molds! I really want this to work!

Yes, the walls need to be quite thick. Concrete has very little tensile strength.

The tradeoff is that concrete walls can be thinner if you are careful and use wire reinforcement, but the concrete container may still be heavier overall. I have some commercially purchased containers that are made from concrete or some concrete type material; they measure about 1' X 1' X 2', and the walls are no more than 3/4" thick, but I believe they are reinforced with fiberglass fabric.

Those are most likely GFRC. Also, compared to ceramic or plastic, 3/4" is huge. You also have to understand how those commercial concrete products are made. They aren't even typically poured but instead are dry packed into forms with presses and released. Then they are lightly misted with water and held in a giant climate controlled warehouse at 90% humidity for a month. This limits the amount of water used to maximize strength. The rest are poured like concrete sinks where an expensive high range water reducer is used to allow high flow with low amounts of water. Then if a nice surface is desired that is poured on top of the main GFRC body. As before, the whole thing is left to cure for a month in a high humidity environment.

Just getting some bagged concrete or mortar from the hardware store isn't going to give you anywhere near the same results. This means you have to go even thicker.

De

i live in iowa too, and i make/use hypertufa.

mine stay outside.

you can 'paint' them with yogurt and moss mixture to give them an aged look too.

dave

bragu - I live in an apartment so I don't have a yard to keep them in, just a small balcony.

It sounds like this is not going to be a good idea for me. I wanted to make some square pots because I've been told that it would help me save space! But if the walls need to be that think it would be counter productive to my goal. Guess I will see what I can find to purchase.

Thank you everyone for your input! It is greatly appreciated!

If you are having trouble with wind, I recommend adding a lot of gravel to your container medium to increase the bulk density. Then you can use lightweight containers if you want. We have pretty serious wind here, the highest recorded at the weather station just about a 1/4 mile away is 101 mph. Except for a 7' epiphyte tower, I don't have problems with wind knocking stuff over. The tower did handle 50mph wind before tipping over, so that's not that bad.