When you want to grow fruit, vegetables or plants indoors, you have several different options. You can use pots and growing trays and move the plants from the indoors out when you want to, or use a designated hydroponic system. A nontraditional method is to use an old terrarium, or fish tank, as your growing base. Tanks provide a good view of the plants and can also provide a sustainable, contained growing situation with good humidity and protection for the plants.
Start with a 20- to 30-gallon fish tank, so that you have room to grow several different plants, and make sure your tank has a glass lid. Because you're going to be growing in a restricted area, choose plants that do well in enclosed, hydroponic situations. Vegetables such as bush beans, peppers and tomatoes grow well in controlled environments.
Fill your tank with a 1-inch layer of large rocks or gravel to ensure good drainage. Put a 4- to 5-inch layer of compost and quick-draining soil on top of the base. This layer must be deep enough for the roots of your plants, so when in doubt, choose a deeper layer rather than a shallow one. Plant your seedlings at their preferred planting depths and spacing. Don't crowd the plants, and put plants that will need support, such as tomatoes, near the walls.
Water your seedlings with 2 inches of water and put the lid on the fish tank. For tank growing, keep the lid on during the day to conserve moisture and slide it off at night to give the plants air circulation. In the restricted area of the tank, where there's no drainage, water will condense and run down the sides of the tank to maintain the moisture in the growing environment for weeks at a time. Check the soil of the tank periodically; if the top 2 inches of soil are dry, give plants another 2 inches of water.
Put the tank in a place where it receives four to six hours of natural or artificial light every day. If you live in a warm area, put the fish tank outdoors during the day, but bring it inside at night or if temperatures drop below 60 degrees Fahrenheit.
Feed plants once a month with a small application of phosphorous-heavy fertilizer, which will encourage blooming and fruiting. Follow manufacturer directions when using fertilizer.