BASIC HYDROPONICS

1. LIGHT

Light is the energy that creates life. Plants/Life cannot exist without it, and cannot thrive without enough of it. Plants process up to 5,000 foot-candles of light intensity to get the energy to grow. The sun is around 1,000,000 foot-candles. Shade can be lower than 1,000 foot-candles.

Plants will enjoy much light, but some do not like all the heat put out by sunlight. Shade cloth is ideal for hot conditions, also to keep plants from, insects, wind, rain and other damage, but rarely is the requirement for low light levels.

Sunlight is an ideal source of light for plants. It is bright and contains the Reds and Blues necessary to produce good healthy growth. However it also has infrared, Green and Ultra-Violet light.

The infrared light or heat is absolutely necessary or we would all freeze to death, but it can be too little or too much heat. Too little heat is best combated by using a recirculating hydroponic system. By heating the nutrient in the tank, and pumping the 20 to 25C nutrient around we can keep the plants warm. Excess heat in summer, can be alleviated by cooling the tank, usually by aerating the tank heavily. By using a venturi, a water jet, or having the nutrient rising and falling into the tank like a waterfall will cool the nutrient as it passes through the air.

It is not necessary to worry about green light as it is usually reflected off the leaves, making them look green. There is some evidence that shows that a reduction in Ultra Violet (or UV) light can improve growth. If you are growing under glass or plastic this may interest you.

We generally grow outdoors, so just use common sense. If you’d feel hot or cold in the sunlight, then the plants would feel that too. Plants tend to grow well in the same climate as humans feel comfortable. A great way to grow is under artificial horticultural lights that will allow more control, and less damage from the elements, but that is a decision you can make. What I can tell you is that, a 400-Watt plant light, costs very little to run, but the benefits are, faster growth (from up to 18 hours of light per day), more control of the seasons through day length, less pest problems, no wind, rain and less cold problems. But you may need an exhaust fan to ensure good air circulation and no heat build up in warm climates. (See Appendix on Artificial Light)

RULE: A PLANT GETS ALL ITS ENERGY FROM THE LIGHT IT ABSORBS THROUGH ITS LEAVES. LOWER THE LIGHT LEVELS AND YOU REDUCE THE GROWTH RATE.

2. OXYGEN TO NUTRIENT RATIO

Oxygen keeps a plant’s roots healthy and allows the plant to take up nutrient. Oxygen is the key to growth rate. Without oxygen around the roots, the roots will rot and die. You cannot grow in water, unless you dissolve oxygen in it. The recommendation is that you do not grow in water, just feed enough nutrients to keep the roots moist, with access to oxygen. The 5 systems I have described in this book will have varying degrees of oxygen according to their design. The oxygen level or the oxygen to nutrient ratio is the key to success.

RULE: PLANTS CANNOT TAKE UP THEIR NUTRIENTS UNLESS OXYGEN IS PRESENT. THE MORE OXYGEN, THE FASTER THE UPTAKE OF NUTRIENT.

3. NUTRIENT STRENGTH

Assuming you have a commercial brand of nutrient made by a company such as Accent Hydroponics, Growth Technology or the like, you will get excellent consistency in the nutrient. Always use a 2 part A&B style nutrient where possible. Nutrients must be solely designed for Hydroponics. Soil fertilisers require bacteria to break down more complex elements into useful ones. They are likely to be less soluble, not pH adjusted, and are usually too slow to release the necessary elements to be suitable for Hydroponic systems. Plants may grow for a little while in Hydroponics using soil fertilisers but they generally exhibit minor mineral deficiencies, then develop major deficiencies, until even changing to a Hydroponic nutrient can not correct the disorders. Soil fertilisers normally kill hydroponically grown plants, but not overnight. Certainly they will never produce as nature intended them to if you do not supply the right amount of minerals in a soluble form.

There are a range of companies offering a grow (High Nitrate) nutrient and a bloom (high Potash) nutrient. Neither will MAKE a plant do anything. You can use these formulas to approximate the nutritional requirements of your plants. When growing, a plant generally takes more nitrates, and during flower production and/or fruit production, plants generally increase their potash and phosphate uptake, but lessen their need for nitrates. However, in cloudy, overcast or short days of the year, the plants will take up more potash and phosphorus due to lower light levels, and on sunny, long, cloudless days the plants nitrate uptake is greater. Sounds confusing? It isn’t really. Most manufacturers put an excess of everything into their general-purpose nutrients. But when in doubt, ask a store. Also, when people tell you an imported nutrient is better, don’t believe them, unless they’ve tested a good nutrient with a growth additive like Superthrive, Budwiser or Organic Growth Promotant (OGP). They will find out smartly, that these nutrients only grow a bit better because of the Americans and other countries put small amounts of hormones or vitamins into their nutrients - and imported nutrients cost more! Use nutrients, and to boost growth, add a good plant hormone and Plant Vitamin treatment to the nutrient. You will be amazed!

Once you have a good brand of nutrients, mix exactly to directions. Less is better than too much. Less will make a plant grow faster, but more stretched, and leafy than normal. More will create a compact plant that hardly grows upward but is extremely bushy, woody, but can be a heavy bearing fruiter/flowerer. If nutrient strength is strong or weak to the extreme, this will lead to deficiencies or death. E.g., too strong, and calcium is deficient because the plant is not taking up nutrient fast enough. If the nutrient is too weak, it is the same deficiency, but due to insufficient calcium in the nutrient. Follow directions and ask a store what to do. Nutrient strength can be read and adjusted by electronic conductivity meters. Ask your store what a conductivity meter will cost. (See also Appendix on advanced nutrient control through CF adjustment)

RULE: THE NUTRIENT CONTENT AND STRENGTH GOVERNS HEALTH, HEIGHT, LEAF AND FLOWER PRODUCTION, AND ALL GROWTH ASPECTS.

4. NUTRIENT pH (ACIDITY AND ALKALINITY)

pH is the level of acidity or alkalinity of the nutrient solution. Think of it as sweet and sour. Most nutrients in town water will be within the range of 6 to 6.5 pH. ALL PLANTS GROW IN THIS RANGE IN HYDROPONICS. Anyone who tells you otherwise, is either horticulturally trained in soil only or is reading materials drawn from soil based research and is therefore untrained for plant nutrition in Hydroponics. I extend my apologies to Horticulturists. Some of you do understand the nutritional simplicities of Hydroponics, but 4 years of soil training is hard to overcome, research into Hydroponics is still new, and soil nutrition is not suitable for the simple Hydroponic plant. If recycling nutrient, pH and Nutrient strength can change as certain elements are taken in by the plant. All you have to do is change the nutrient for fresh nutrient as often as possible, or adjust to the correct reading with a set of meters. If the nutrient is too sweet or too sour, the plants will develop deficiencies. I will discuss manual care, electronic adjustment, and computer control later. As discussed in water purity - pH must be checked if you are using rain, dam, bore water or any other source than town supply.

RULE: pH IS THE KEY TO KEEPING PLANTS FEEDING ON THE CORRECT ELEMENTS, AND KEEPS THEM FROM DEFICIENCIES.

5. TEMPERATURE AND FRESH AIR

Optimum temperature depends on the plants. Generally, Phosphorus up-take is severely impeded below 15 degrees Celsius, so that’s our bottom temperature. It is recommended to heat the nutrient if it is below 15 degrees Celsius for more than 4 hours per day. Maximum temperatures are, (as a guide) around 30 degrees Celsius but as long as it is well below the temperature where humans start to sweat the plants should be all right.

Use common sense. If the plants are in 20-25 degree temperatures and 40-60% humidity, then it is likely that you would feel comfortable where the plants are. By coincidence, plants tend to grow best in climates approximate to human comfort. So if you visit your plants and it feels like a blast furnace, or a freezer, it is likely they would benefit from some attention on the matter. Fresh air is absolutely essential in shade-house, tunnel-houses, glasshouses and grow-rooms, as the Carbon Dioxide the plants breathe is essential for every plant process. Poor ventilation will kill plants, as surely as poison. You will notice ventilation problems by the better growth near vents, doors, or fans. If plant growth is more sluggish away from these areas, then you should improve your fresh air, or use Carbon Dioxide enrichment systems to add CO2.

RULE: PLANTS NEED CARBON DIOXIDE IN EVERY PLANT PROCESS. THEY NEED FRESH AIR, NOT TOO MUCH HEAT OR THEY CANNOT PROCESS DUE TO WATER LOSS AND NOT TOO COLD OR THEY CAN’T GET THEIR FOOD.

6. WATER PURITY

Town water is generally suitable for Hydroponics, but if you are using bore water, spring water, dam water or rain water, you may have to check to see if this is suitable.

What problems could occur, is the salt content of the water, may be too high, the zinc content from metal (zincalume) tanks, could make it toxic for plants (even though it may be still safe for us to drink), as well as any number of chemicals, poisons or fertilisers, could be contaminating the water supply. Please speak to a Hydroponic Company about the water supply if you are unsure.

In all the above cases, pH control of nutrients is required.