Creating an herb garden out of a discarded aquarium is a simple process. When you have completed the project, you'll have an attractive, useful indoor garden. One of the most important components for success is access to full sun. Herbs thrive in this environment and must have plenty of bright light to reach their full growth. Otherwise, you will end up with thin, spindly plants that lack flavor. Before attempting to build an herb garden indoors, make certain you have an appropriate spot to place your aquarium for your plants' optimum health.
Fill the aquarium with water and add some dish soap. Using a soft cloth, clean the aquarium thoroughly. Discard the soapy water and rinse well, and make certain to remove all trace of soap. Dry and polish with a soft cloth, or discarded dishtowels.
Place a 1-inch layer of gravel inside of the aquarium, covering the bottom entirely. Add an even layer of activated charcoal on top of the gravel, bringing it up to about one inch.
Fill the aquarium with high quality potting soil until it reaches within 5 to 6 inches from the top.
Plant either seeds or seedlings in the soil. You can purchase miniature tools for container gardening, or use an old spoon or fork. Water sparingly, taking care never to over water. When in doubt, remember it is better to use too little rather than too much water.
Move your aquarium into the sunny spot you have chosen. Your mini garden should start to flourish within a week.