This planter also has a vertical feature. I did not just want to leave that end covered up, so I fashioned a way to plant some sedums on the vertical face of the planter.
If you don't know folks who work in a science lab at a university, you might not come across suitable pieces. If you live near a university, however, you can always swing by the garbage outside of physics, chemistry, or engineering labs once in a while; often you can find some quality junk waiting to be thrown out.
Step 1: Find Some Junk
My junk was formerly part of a plasma generating ring, seen here. This is a nice shape because you could place it in a number of ways: as seen in the picture, or on its rounded side, in which case you'd leave the rectangular plate on top and have plants growing out of the two circular ends.
What else you'll need:
Enough rocks - the amount of rocks needed depends on your planter size
Enough dirt - the amount and type of dirt depends on both your planter size and your plants' preferences
Some plants - enough to fill the space
Wire mesh - some fine mesh (window-screen mesh) and wider, stiffer mesh
If you have a vertical hole, you will need some kind of clamps or glue
Step 2: Add the Rocks
1. Most importantly, the addition of rocks at the bottom will help with drainage. If there was dirt all the way down, it would easier for the soil to become waterlogged, especially since there are not holes at the bottom of this vessel to allow excess water to escape.
2. The plasma planter is slightly unstable standing on its end, especially once we install the plants and dirt, so having heavy rocks at the bottom are a good way to weigh down that end.
3. Rocks are usually cheaper than dirt, so the more rocks you use, the less soil you have to use.
I filled the vessel most of the way up to the top of the bottom curve with rocks. This was one bag of rocks from my local garden store, but you could probably just find some rocks or boulders around in nature. Unfortunately, nature does exist in Los Angeles, just garden stores.
Before adding the rocks, you want to place the planter on a base and seal it with caulk. This may not be crucial in all projects, but is especially important if your planter is unstable and may need some help staying in place.
Step 3: Add the Soil and the Plants to the Top
Next, you can add the plants at the top. I put in a mesh wall inside the tube to help separate the tube into two spaces. This both helps stabilize the dirt and allows for me to be able to remove the vertical feature if it dies (which is more likely, since it's slightly more difficult to water).
Step 4: Add the Vertical Feature
You should have, at this point, cut a rectangular hole into the mesh pieces that will be the portal for the plants of the vertical feature to come through. The final step is to put the plants into the tube before you put the mesh in place, and then thread the leaves/body of the plants through the hole so that the roots are held in by the mesh, but the plant bodies are growing out. I chose sedums because they should cascade down as they grow, but in retrospect, parrots beaks would be an even better and more beautiful choice.
Place your planter someplace sunny, and enjoy!