Hydroculture is a way of growing many different types of plants without using any sort of soil at all. Hydroculture is a form of hydroponics, and the two main styles are sometimes referred to as passive hydroponics or active hydroponics. Hydroculture has a number of benefits over traditional soil-based agriculture, especially for growing house plants, and many people are turning to hydroculture to help them keep better care of the plants in their home.
Most hydroculture is done using some sort of aggregate, which is highly absorbent, and nutrients which are added to the aggregate. The most common form of aggregate are expanded clay pebbles, which has been fired to have a porous and open inner structure, and a hard outer shell. These pebbles absorb a great deal of water, and are fairly light and easily transported.
Just like soil, these clay pebbles can absorb both water and nutrients that you add to them, and the plants in turn can gather the water and nutrients from the pebbles. The same capillary action that takes place with soil takes place with this aggregate, but it has a few advantages over traditional soil. For one thing, since there is much more space between the "soil," and since hydroculture is often done in transparent reservoirs, one can easily see at a glance whether there is sufficient water in the aggregate to nourish the plant, while soil’s opacity can make this difficult to determine. For another, the extra space between the pebbles means that the roots of the plants are able to breathe much more easily than with traditional soil, which can help prevent all sorts of rot and other problems that plague plants.
Since the aggregates used in hydroculture do not naturally have many minerals and nutrients in them, the way natural soil does, and since adding things like fertilizer to aggregate would not be feasible, there are special nutrient solutions used in hydroculture. These solutions can be purchased at any hydroponic specialty store, and usually come either as a powder, a liquid, a tablet, or a resin. The powders and the liquids are simply added to water and put into solution, and then the water is added to the aggregate reservoir. The resins and the tablets tend to take much longer to release, and so require much less upkeep, with some resins requiring interaction only every few months.
Moving a plant into a hydroculture set up is relatively easy, although it does take some preparation. While it is possible to move a plant from soil to hydroculture, it is less likely the plant will take hold than if you water root the plant to begin with. To do this, one suspends a cutting of a soft-stemmed plant into a bit of water, usually by putting it through a hole in a plank of wood or a cardboard. The water needs to be changed regularly, but over time the plant will develop a root system. Once a little bit of a root system has been established the plant can be moved to a hydroculture arrangement, where it can be propagated on just water for a time in a high-humidity environment, and eventually nutrient solution can be added and the plant can be grown entirely by hydroculture.