Did you know...?
The term "succulent" refers to a large group of plants that have evolved to survive in Arid climates with minimal water. Most succulents store water in their thick, fleshy stems and leaves, which is how they got their name (from the Latin sucus meaning juice or sap). They are prized for their distinct colors, shapes and unique growth habits. Most Cacti are considered succulents as well, and can be cared for in the same manner.
Succulents make excellent terrarium plants, provided they are given enough light. Because their root systems are generally small and shallow, many varieties of succulents can be clustered together without impeding the growth of their neighboring plants.
Caring for your succulents...
Succulents require bright light, but minimal care otherwise. They are very hardy, and can live off of the water they store in their leaves for quite a while. To keep your cactus or succulent happy, place it in a location where it will receive 7-10 hours of bright sunlight per day. In or near a bright window is ideal. If you don't have a bright enough location, providing supplemental light with a fluorescent or compact fluorescent light (cfl bulb) will often do the trick.
Succulents and cacti should be watered sparingly approximately once every 10-14 days. In a terrarium, where there is rarely drainage holes for excess water to run through, water just enough to saturate the soil around your plants roots, without adding too much excess moisture to your terrarium. A rule of thumb is approximately 1/4 cup of water for a 2" plant. Be sure to target the water right at the base of you plant. A turkey baster or similar works very well for this. If your plant is not in a terrarium, and is kept in a container with drainage holes you can simply water until the excess begins to drain out of the bottom, then place your plant somewhere that the excess can continue to drain.
Fertilizing needs will vary based on succulent variety. A quick internet search will provide information for your specific plant type.