THE BASICS OF HYDROPONICS - What Do Your Plants Need?

Hydroponics Gardening part 2 in this series of articles about the basics of Hydroponic Gardening talks about what your plants need.

Hydroponics Gardening - An Introduction To Hydroponics Gardening For Beginners (Part 2) Plant Needs
By John R. Haughton

All plants need the correct conditions in order to grow to their full potential. Plants grown using hydroponics systems are no exception to this basic rule. Like their soil grown cousins they need sufficient light of the correct wavelengths, a suitable temperature, an adequate water supply, enough oxygen, mineral nutrients and support for their structures.

• Sufficient light of the correct wavelengths, used by the plant at the growth stage it has reached, is essential for its survival. Plants use lots of light, at least 8 to 12 hours each day, in order to make carbohydrates from CO2 and water. Chlorophyll, the green colour in plants, absorbs the sunlight and uses its energy to synthesise these carbohydrates. This process is known as photosynthesis and is the basis for sustaining life in all plants. Because animals and humans get their food by eating plants, it can also be said to be the source of our life.

  Artificial lighting is generally a poor substitute for sunshine, because most indoor lights provide insufficient intensity to produce a mature crop. High intensity lamps such as high-pressure sodium lamps can provide more than 1,000 foot-candles of light. The hydroponic gardener can use these lamps very successfully in areas where sunlight is inadequate. The fixtures and lamps, however, are usually too expensive to be viable for a small commercial operation.

  It is important to allow adequate spacing between plants as this will ensure that each plant receives sufficient light in the grow-room. For example, tomato plants, pruned to a single stem, should be planted so as to give 4 square feet per plant, while European seedless cucumbers should be allowed 7 to 9 square feet and seeded cucumbers about 7 square feet. Lettuce plants need to be spaced 7 to 9 inches apart within the row and 9 inches between rows. Most other vegetables and flowers should be grown at the same spacing as recommended for a conventional garden.

• A suitable temperature is required for the plant to grow normally. Temperatures that are too high or too low will give rise to abnormal development and reduced production. Summer vegetables and most flowers grow best between 60° and 80° F, while winter vegetables like spinach and lettuce prefer temperatures of between 50° and 70° F.
• An adequate water supply is not normally a problem when using a hydroponics system, since the basis of hydroponics is the supply of water containing nutrients in solution. Having said this however, there are some systems which can give rise to inadequate watering, with the consequent detrimental results to your plants. Ebb and flow systems which are not checked on a regular enough basis, can run short of nutrient in their supply tanks, as can continuous flow systems. Most, if not all, automated hydroponics systems can have disasters if they are not monitored closely. A blocked or burst pipe, or a pump failing can result in lack of nutrient flow, which, coupled with the intense lighting and the correct ambient temperature in the grow-room, will result in dry roots and severe damage to, or even the death of, your plants.
• Oxygen is a basic requirement of most living things. Plants need oxygen for respiration, so that they can take up water and nutrient. In soil systems enough oxygen is usually available, but plant roots growing in water will quickly use up the supply of dissolved oxygen. This can damage or even kill the plant unless additional air is provided. A common method of aerating the nutrient is to bubble air through the solution. Continuous flow and aeroponic systems do not usually need supplementary oxygen.
• Mineral Nutrients are needed by most green plants. They must absorb certain minerals through their roots in order to survive. In conventional horticulture these minerals are supplied by the soil and by the addition of fertilizers such as manure and compost. Nitrogen, phosphorus, potassium, calcium, magnesium, and sulphur are needed in large quantities, whilst the micro-nutrients, iron, manganese, boron, zinc, copper, molybdenum, and chlorine are also needed, but only in very small amounts.
• Support is normally provided by the soil that surrounds the growing plant. A plant grown using hydroponics however needs to be artificially supported. This is usually done with string or stakes. It is possible to buy inexpensive automatic string reels to support your plants as they grow. This cuts out the tedious task of having to keep re-adjusting the strings on fast growing plants.

Copyright (C) 2004, 2005.
J R Haughton.
--- All Rights Reserved ---

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