Hydroponics is a method of growing plants without soil. This soil less gardening actually is more efficient. Hydroponics methods reduce both water and nutrient requirements. It increases the amount of plants that can be grown in a given space.
The Three Things Soil Does
Plants growing naturally have three needs met by soil.
Water - Water is contained in the soil. Plants have developed amazing methods of finding water. Just look at how far tree roots can grow.
Nutrients - Nutrients are dissolved in water. So when plants draw nutrients from the soil they are actually getting it from the water, not from the soil directly.
Support - All kinds of plants, trees, flowers, vegetables use ground as support.
Oxygen - Soil does contain oxygen, which plants require to absorb nutrients.
Logically, following from the above, an indoor hydroponics gardener will have to supply his/her plants with the following:
A source of aerated water.
Nutrients - nutrients are mineral salts easily dissolved in water. So the gardener can just make up a batch of nutrient dissolved in water and add precisely measured amounts to the garden. You don't need special nutrients. You can use the ones found in local hardware stores or garden centers. Because of the efficiency hydroponics affords, you only need to use ¼ of the amount recommended.
Support - Land plants usually require support to grow upright. For support you can use sand, marbles, or clean pottery shards. For hydroponics gardeners, aggregates (such as sand, perlite, vermiculite) also function as support.
As strange as it may seem, soilless gardening really works. An added benefit for your indoor hydroponics efforts, your plants will infrequently fall victim to various germs, parasites and other pests.
Why is Soilless Gardening More Efficient?
Without the necessity to seek out food and water, plants have more energy to grow. Because they do not require extensive root systems, a gardener can grow more plants in a smaller space.
Soilless gardening is one of many methods the indoor gardener can use. Of course plants require more than water, air (oxygen), nutrients, and support. Light, pH (the acidity of the water), and temperature of the environment are important for setting up any garden. For more information on hydroponics, especially for beginners please see http://www.indoorhydroponicsblog.com