Hydroponics

hydroponics is a form of soilless culture where plants are grown in nutrient solutions, with or without the use of an artificial medium. Hydroponics is highly productive; it is a method that conserves water and land. It is also safe for the environment. Hydroponics is high tech, but requires only basic agricultural skills to begin with. It is important to regulate air and root temperatures, among other factors like light, water, plant nutrition and extreme climates. For this reason, hydroponics systems must often operate in temperature-controlled environments like greenhouses. It is very important to pay proper attention to the greenhouse conditions else hydroponics will stop being cost-effective for you.

In liquid hydroponics systems, there is no supporting medium for the plant roots. This is also known as solution culture; the three main types of solution culture are solution culture, continuous flow solution culture and aeroponics.

In the former, plants are grown in containers of hydroponic nutrient solution. They are typically home-level applications where hydroponics systems function in glass jars, plastic buckets, tubs and tanks. The solution is sometimes gently aerated but can also be unaerated, in which case the solution level is low enough so that some part of the roots get access to regular oxygen supply. The nutrient solution is changed as per a predetermined schedule, mostly once a week.

The continuous flow solution culture is orchestrated differently, with the hydroponic nutrient solution flowing past the roots. A popular version of this culture is the nutrient film technique; here, a very shallow stream of water containing all the dissolved nutrients needed for plant growth is circulated past the roots of plants. The hydroponic nutrient solution travels in the lower half of the roots, which forms a watertight root mat, while the upper sections of the roots are exposed to air and get a good supply of oxygen.

Aggregate hydroponics systems, however, have a solid natural or artificial medium of support. Hydroponics systems can also be open – where the nutrient solution is delivered to the plant roots and not reused, or closed, where the surplus solution can be recovered, replenished and recycled.

Every crop has very specific requirements and like in another other method of agriculture, hydroponics must pay attention to the unique needs of each crop. Hydroponics systems are rapidly evolving today and yields are increasing manifold, touching heights we had never envisaged. Hydroponics is possible in places where natural agriculture isn’t, including deserts and space stations. People living in densely-populated places can grow their own fresh vegetables in rooftop gardens or windows using hydroponics. Hydroponically grown plants also grow faster and are relatively free of soil-borne diseases.

Hydroponic Media

Often, people assume hydroponics means growing plants in water, but in reality, hydroponics is a term used to refer to plant production without soil, using water and a wide range of organic and inorganic materials. Which medium you use depends on your hydroponics gardening needs. There is no soil in your hydroponics system, but your plants will still require anchoring and there are a wide range of inert materials that can be used to support plant roots. They are called ‘growing media’.

Perlite, rockwool, clay pellets, coir (from the husk of the coconut), vermiculite, sand and gravel are some common growing media. The ideal hydroponic medium provides plants with adequate support, is moisture absorbent and allows good air circulation. It should also preferably be pH neutral.

Perlite is a volcanic rock that is a fusion of granite, obsidian, pumice and basalt, obtained at very high temperatures. The final product formed by heating at high temperatures is lightweight; they are expanded glass pebbles. Perlite can be used to decrease soil density. It holds more air and less water than vermiculite. It can be used loose of in plastic sleeves that have been immersed in water.

Vermiculite is also a superheated medium that has expanded into light pebbles. It holds more water than perlite. The natural wicking properties of vermiculite mean that water and nutrients can be easily drawn from it in a passive hydroponic system. But if its good capacity for water retention hampers air circulation, you can lower vermiculite’s water retention properties by mixing it with another medium.

Rockwool is the commonest medium known to hydroponics. It is cheap, inert and simple to use. It works in both free drainage and re-circulating hydroponics systems. It is made from molten rock that is spun into thin clusters of fibre. Hence it is conducive to capillary movement but not degraded by microbiological activity. It is a high density medium, and that improves the dispersal of nutrients and moisture, suffusing the medium with fast-growing roots to increase nutrient absorption and create the best conditions for plant production. One can sterilize and reuse rockwool, but most growers only use it once.

Other common hydroponic media are coir and gravel. Coir is a completely natural growing medium used in hydroponics. Made from the outer husk of the coconut, it is full of trichoderma bacteria that protect roots and stimulate root growth. It is easy to use because it has a perfect air-to-water ratio that prevents overwatering. It has a high cation exchange rate, so unused minerals are stored by it and released to the plant as needed. Gravel comes in different shapes and sizes, but it is washed before use. Water is circulated using electric pumps through the medium. It is inexpensive and clean to maintain. It doesn’t cause water-logging. But it is heavy and the gravel hydroponics system requires a regular supply of water to prevent plant roots from drying out.