You asked about my construction vs that method. Look at all those holes. Look at the cutting required to fit the pot. PITA.
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Here's what I did:
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Corrugated drain pipe with drainage slots. The stuff is so easy to work with, you can actually cut it with scissors. You can even buy the end caps to make it less work. (as I've done here) Do this X3 per container, and drill a hole in cap per container.
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Then, you only have one more hole to drill:
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I don't know about you, but I don't particularly like cutting and drilling in thin plastic. So from a construction standpoint, this is so much more easy and practical. Plus, there's the capacity and lower center of gravity (these containers literally cannot tip over).
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I had this fella in one for almost 4 seasons, before I lost it to a hurricane (this was taken just after the storm that claimed it):
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