Concrete Rocks!

First off, I have to say that this was written a couple years ago, and I am just now publishing it. I’m going to try to start posting some current projects, but we’ll see how that goes with my currently workload.

Anyways, I had been doing some gardening and planting around the house. I would consider my success low to moderate. After several months, my list of garden related projects has grown more than anything in my garden.

One of these projects started with trip to Home Depot with my wife and the purchase of a lemon tree. It is a very cute little lemon tree, and we decided that it would be best planted in a planter… a large planter. The requirements handed down were:

  • About 50 gallons
  • Not plastic
  • Not square

I looked around online, and didn’t find anything that directly met these requirements. Most of the large planters were squarish, too small, or plastic.

There is facility near our house that manufactures concrete sculptures, fountains, bird baths, and anything else they dream up. A quick trip there revealed a couple of things: concrete pots are expensive, concrete pots are heavy, and they aren’t typically near 50 gallons.

What is the logical conclusion? Make one.

After some research, I decided to have a go at it. There are quite a few online resources describing different ways to go about making a large planter, some of them kind of agree with each other, but none were exactly what I wanted.

I did have a large plastic planter, and I decided to use that as a starting point. It became the mold, and I essentially stucco’d the inside of it. For the sake of anyone else that wants to follow this pursuit, I am going to include some of the basic steps.

Find something to use as a form. As I mentioned, I had a large plastic planter that probably came with a tree at some point in the past. It obviously didn’t meet the no plastic requirement, but it worked well as a starting point.

Make sure that the the form will hold the concrete. My form had holes, but some duct tape remedied that.

How to remove the planter once the concrete sets? After looking at much conflicting information online, I went with a thin layer of motor oil as a release agent.

Is reinforcement required? I don’t know, but placed chicken wire in the mold. I do not know if it is serving any structural purpose, but it definitely acted as a lath to hold the concrete before it set.

What type of concrete to use? I spent quite a bit of time researching it. Online sources didn’t seem to be in agreement, so I finally just went to a masonry supply store, gave them my credit card, and bought what they told me. It is some type of mortar used for stucco that has fiber reinforcement. I hate to say it, but I’d suggest just going to the store and consulting a professional.

How best to remove it from the mold? This was my favorite part. Notice the piece of 3/4″ PVC protruding from the base of the planter. Not shown is an open flange to mechanically hold it in place that also serves as a hydraulic conduit to the microannulus between the plastic mold and the concrete planter. I pumped water down the PVC which then filled the microannulus in an attempt to “float” the concrete planter out of the form.

Was floating the concrete out successful? Kind of.

It did actually float. However, that didn’t help me to get it out. I ended up tipping everything over and dragging the planter out by its PVC. I made two more, and on those I did not even try to float the concrete planter. Instead I just tipped the assembly over, rolled it around to separate the concrete from the form, and drug it out with the piece of PVC.

It has been a couple years since I created these and they have served me well… two contain olive trees and one a lemon tree. I plan to post the final product in the near future.

IN CONCLUSION:

  • Will I make another? Hopefully not.
  • Is it neat that they were home made? I guess if you’re naive enough like that kind of stuff.
  • Are they heavy? Absolutely… it takes a forklift to move them around.
  • Would I prefer a plastic planter? Absolutely.

While the heft of my home made planters might act as a theft deterrent, I’d argue that thieves could find something more valuable to steal than my olive and lemon trees. Unfortunately, most would argue otherwise.

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