A container provides the structure of plants. Although containers are very important, they are relatively simple. Containers should be the same width at the top as the pot is deep. They should also usually have holes for drainage at the bottom. While it's not impossible to grow plants in containers without holes (e.g. terrariums), it makes watering the plant more difficult, becuase of the risk of overwatering. If you don't overwater, terrariums make great containers. With just a little effort, you can get a very low maintenance container for picky plants. Be sure and line the bottom of a terrarium with pea gravel a sprinkling of gardener's charcoal (to keep the water clean) some peat for absorbency potting soil Many of the plants in the terrariums above are ones that are usually difficult to grow because they need a high level of humidity. The terrarium on the right, created from a one-gallon fish tank, holds a button fern. The larger terrarium (10 gallon aquarium) on the left holds several palms (that are getting big for the tank), a button fern, an Australian maidenhair fern, a Christmas cactus, Baby's tears, a spider, and some as-of-yet unidentified plants.