You can of course make these planters from new materials, but you can save quite a bit by repurposing used metal or plastic culverts. Check places like Craigslist for used culvert, and make contact with excavators and your county or state road crews as they sometimes have ends or damaged pieces where portions are still useable. You aren’t as likely to get metal pieces since those can be recycled, but it never hurts to ask.
How to create your planters
Once you have obtained your culvert pipe, you need to decide if you want to stand them upright, or split them in half horizontally and lay them in rockers on the ground.
The black plastic culverts help warm up the soil early and are good for things like melons, eggplant and tomatoes or any other veggie that likes warmth.
Metal planters can have sharp edges, so you need to get some small plastic tubing that you can split and run around the edges to keep injuries at bay. I have also seen people build octagonal wood shapes around the tops which if done well can give them an upscale look.
Vertical planters just need to be cut to the height you wish to have your planters standing. From the same 4ft piece of pipe, you can create one tall planter, or several shorter ones, although I wouldn’t recommend anything shorter than 8 inches. Taller planters are good for people with back issues as they won’t have to stoop to weed. They are also good for root crops.
For taller planters, you can fill half or more of the planter with gravel and the top portion with garden soil. This provides good drainage and saves you a bit on the cost of good soil.
Horizontal planters are a little tougher to cut as they need to be braced the entire length of the pipe while you cut them and they require a cap at each end to contain the soil. And then need to be braced so they don’t tip to one side or the other. They also need to be planted a little differently with shallow-rooted crops at the outer edges and deeper rooted crops in the middle.
Planters like these are especially good for perennial crops that can become invasive such as horseradish, asparagus or rhubarb.
