The other important part of owning a plant is caring for it. Water it weekly (duh), but also check it regularly for signs that it needs to be repotted. When a plant grows to several times its size, that means its roots are growing, too. Eventually, the roots will become a tangled mess and won't be able to function as well. Plants also need fresh soil every year or so, in order to restore some fresh nutrients. You may also accomplish this with fertilizing plants 2-3 times yearly. When the tips of plants' leaves become yellowed or brown, start falling off, or the plant stops flowering, you probably need to remember to water it, or repot/feed it.
If you don't have the greenest thumb, pick something that is low maintenance, like succulents or cacti. Bamboo is also easy to grow, it just needs to be kept filled with water. Spider plants are also very easy to care for (and aren't as scary as the name implies).
Word of warning, though. These kinds of creative pots cannot drain water, so you will have to be more diligent about how much you water and how often. Water less, but make sure the soil is still somewhat moist. A larger container with more dirt means more area the water can be absorbed into, so the plant shouldn't drown.
Here is the outcome of my thinking outside the pot, creative technique...
Happy planting! Keep it zen, my Arrow readers.