Growing African Violets and other houseplants hydroponically Introduction and some history Why Hydroponics? To the uninitiated, hydroponic growing simply means growing plants in water without soil. Unfortunately, however, there are a just a few aquatic plants that can be grown in water alone. Plants grown hydroponically require the same conditions for optimum growth as plants grown by any other methods: water, nutrients and air. Hydroponics, in its simplest form, is growing plants by supplying all the necessary nutrients in the plant’s water supply rather than through the soil. The word derives from the Greek words hydro and ponics, meaning water working. Ancient History The science of growing plants without soil is not a new concept. It is at least as ancient as the pyramids. Many scientists have suggested that the earliest attempt at growing plants hydroponically was made by King Nebuchadnezzar, when he built the famous “Hanging Gardens of Babylon”. They are considered one of the seven wonders of the ancient world. Egyptian hieroglyphic records dating back to several hundred years B.C. describe the growing of plants in water along the Nile without soil. The world’s rice crops have been grown in this way from time immemorial. The “Floating Gardens” of the Chinese, as observed by Marco Polo and described in his famous travel journal, are another example of hydroponic culture. To escape their enemies, the ancient Aztecs, a nomadic tribe, reportedly took to Lake Tenochtitlan, located in the great central valley of what is now Mexico. Denied any arable land, they learned how to build rafts of rushes and reeds, lashing the stalks together with tough roots. On these rafts, called Chinampas, they piled the nutrient rich soil from the shallow bottom of the lake and raised food crops, flowers and trees on the rafts. Some of them even had a hut for a resident gardener. The roots of these plants, pushing down towards a source of water, would grow through the floor of the raft and down into the water. The Chinampas were joined together to form floating islands as much as two hundred feet long. Eventually the Aztecs defeated and conquered the other tribes. Despite the great size their empire finally assumed, they never abandoned the Chinampas on the lake. They continued to be used on the lake well into the nineteenth century. Modern science The earliest recorded scientific approach to discover plant constituents was in 1600 when the Belgian Jan van Helmont showed in his classic experiment that plants obtain substances from water. In 1699, the British scientist John Woodward grew plants in water to which he added varying amounts of soil. He concluded that while there are substances found in soil that promote plant growth, the bulk of the soil is used for support. In 1856 Salm Horsmar developed techniques using sand and other inert media. The next step was to eliminate the medium entirely. In 1860, Professor Julius von Sachs published the first standard formula for a nutrient solution that could be dissolved in water and in which plants could be successfully grown. This marked the end of the long search for the source of the nutrients vital to all plants and this was the origin of Nutriculture. By the late 1800s, horticultural scientists were successfully raising plants in solutions of water and minerals. Interest in practical application of Nutriculture did not develop until about 1925 when the greenhouse industry expressed interest in its use. Greenhouse soils had to be replaced frequently to overcome problems of soil structure, fertility and pests. In the late 1920s and early 1930s, Dr. William F. Gericke of the University of California was experimenting growing plants without soil using nutrients dissolved in water and found the soil is not necessary except to anchor the plant’s roots. He coined the name hydroponics. The popularity of Hydroponics has increased dramatically in a short period of time. It has been adapted to many situations from outdoor farming to greenhouse and now in-home gardening. Even NASA has started to experiment with growing plants in space. Why does hydroponics work so well? When you look at a plant as a living being, the answer is quite simple. If you give your plant exactly what it needs, when it needs it, and in the amount that it needs it in, the plant will be as healthy as is genetically possible. With plants grown in soil it is an almost impossible task, because you don’t know really what the plants are getting. That means growing houseplants like African Violets becomes a big guessing game. How much nutrient does the soil contain? What about the micro-nutrients? Even if you buy all the time the same brand you can’t be sure. Very often the manufacturer makes some changes without notice. If you prepare your own soilless mix, you’ll have the same problem. Unless you’re doing every time a soil analysis, you just don’t know, you have to guess. What about the fertilizer? Should I fertilize and how much do I apply? How much of what I applied the last time was washed away when I watered the plants? With hydroponcis the plants are grown in an inert growing medium, the plants do not get anything from the growing medium. The growing medium for hydroponically grown houseplants like perlite, vermiculite, rockwool, coconut coir, and expanded clay bubbles are sterile. The plants receive only what you give them, nothing more. That means you have complete control over pH, nutrients and the nutrient strength. Thanks to Hannah