making cement outdoor plant containers

March 23, 2005 1:11 PM

we have a deck on our house where I've planted tomatoes in the past. we wanted to get a custom plant container that is 3 feet high, 6 feet long and 2.5 feet wide custom made for that space. it is prohibitively expensive. i thought I remember reading somewhere about making plant containers using concrete and peat moss or something to make it lighter in weight. i think i read it in martha stewart or something. i can't remember how to do it. it's not a big deck so the dimensions are really limited. any suggestions?
posted by dstrouse91 to Home & Garden (12 answers total)

There was an excellent step-by-step description of how to do what you're talking about with pictures in This Old House, March 2005 issue - there's no article online, but it was this issue. The article in question is: "Rock from an Easy Place: Make a garden trough with all the character (but none of the hassle) of hand-carved stone". You might still be able to pick it up at the newsstand, the new issue is just coming out now.
posted by true at 1:26 PM on March 23, 2005

I'd just build it out of wood. Seriously. If you build it out of a light mix of concrete, you have to build a mold for it first, I would think, which is the same as building it out of wood, but with the added cost of throwing away the mold when you're done.

There are several ways to go with making a wood one. You can go expensive, cheap and cheapest.

Expensive would be to build it out of redwood or cedar decking. You could also use pressure treated decking, and PT wood is supposed to be safe around food/leaching into soil, but still, ugh. So the decking would handle the rot of the wet earth pretty well because of the kind of wood it is.

Cheap would be to build it from plywood. Easy, fast, maybe not as pretty as the decking, but you could always dress it up. It would last a long time, especially if you built it out of marine plywood, but then see issues of pressure treated etc.

Cheapest would be to build it out of scrounged pallet wood. Plentiful and easy to find behind almost any box store. Free. Not pretty at all, but can be dressed up. It would wear out eventually, but then it is free, so that might be alright.

Make sure to include drain holes, and line the inside with lanscaping cloth if there are any big gaps between boards, or with window screen.

(or you could find an old horse trough, which also works well)
posted by OmieWise at 1:30 PM on March 23, 2005

Another option would be to use synthetic decking, at a cost somewhere between cedar and plywood. That's what we used for our raised beds. Won't rot, is food safe, and doesn't split, even when screwing or nailing in end grain. We got ours at Home Depot.
posted by MrMoonPie at 1:34 PM on March 23, 2005

The material your looking to make is called Hypertufa. . Or sometimes Hypertufta. Tufa is a very porous limestone that you can work with nothing much more than sharp stick. Because most of us do not have a tufa quarry nearby a substitute was developed.
posted by Mitheral at 1:46 PM on March 23, 2005

I have seen this method discussed elsewhere (can't find the article I remembered, tho) & it's supposed to work well - might do for you if you can score some old whisky barrel halves...
posted by Pressed Rat at 1:48 PM on March 23, 2005

PS: a metre is pretty tall for a flat sided retaining wall which is basically what you are building. Since tomatoes only need 20-40 cms of space for roots I'd recommend using a false bottom to limit the amount of soil you are holding back. This will also limit the amount of concentrated mass you are putting on your deck.
posted by Mitheral at 1:57 PM on March 23, 2005

Get some heavy-duty casters for the wooden planter, or for a dolly if you go with the hypertufa. (That sounds like one of those made-up marketing-consultant names.) The planter will need to be elevated for drainage anyway, and it's nice to be able to move it around for sun, clean-up, etc.
posted by vetiver at 2:04 PM on March 23, 2005

I've done this. I think it's called just tufa. The biggest problem is, you need a form, something to pour the mixture in. If you build a form, why not use the form? I made one planter from a wooded planter form, the form got wrecked in freeing it from the hardened tufa. Same with a round bowl shaped one. The extra large plastic bowl I bought for the form cracked when trying to remove it. I supposed there are ways around this problem but I was never motivated enough to try again. Still have the planters though. Nice they are too. Why not just use a cheap garbage can, or do one of those upside down 5 gal. can deals and hang them. The tomato plant grows up toward the sun, makes it easier to tend the plant and is weird enough to start conversation. As any gardener knows, half the fun is getting to show off.
posted by NorthCoastCafe at 2:33 PM on March 23, 2005

I made planter boxes a decade ago, using nothing more than ordinary 2x4s and 1/2" plywood. Plastic-lined on the inside, and siding to match the condo's on the outside. They looked as good the day I sold the condo as the day I built them.

A couple tips: have a false bottom, because you really don't need a ton of depth to keep tomatos happy; slope the bottom for drainage; and use 4" wide wheels to spread the weight (weenie little wheels may very well dimple your decking.)

There are plenty of 10 to 20gal planter pots that will do just as well for tomatos. The things are just dead easy to grow.
posted by five fresh fish at 2:39 PM on March 23, 2005

HGTV did a segment on making your own rocks.

This site suggests using a large cardboard box for the mold.
posted by jlkr at 4:56 PM on March 23, 2005

Gardenweb has a whole forum dedicated to Hypertufa, and it's quite active.
posted by kmel at 7:04 PM on March 23, 2005

The key to getting forms off of concrete is some sort of form release agent. If you don't care how it looks, you can use motor oil. Vegetable oil is probably a safe and non-staining alternative. Spray/coat the inside of the form before you pour your concrete and you should be fine.
posted by electroboy at 11:56 AM on March 24, 2005