All living things need space in which to live, grow and reproduce and plants are no exception to this rule. But unlike other living things that can move from place to place to make the best use of other available essentials like water, air and light, plants have to get these from the limited space in which they grow. Plants are therefore more vulnerable to deprivation of essentials if they are not provided enough living space. Therefore it is important in hydroponics cultivation as in conventional cultivation to carefully assess the space your plants will need and plan ahead keeping in mind their increasing space requirements as they grow.
Spacing of plants is an important aspect that needs to be carefully considered and properly addressed for successful hydroponics cultivation. In the event of plants being grown too close to one another, they will most likely receive less than the required amount of light. Depending on how close they are grown they may even receive less air than they require for normal growth.
Space Requirements
When the plants are just seedlings or cuttings they can be grown in close proximity, but as they grow their space requirements will increase and they will need to be moved or thinned out. In farms and gardens, this is achieved by “culling” the smaller or weaker plants thus making space for the stronger and more aggressive plants to thrive in. With more “living space” now available for the remaining plants, they can more intensively utilize the available area for healthy growth. More area for growth means more air flow to prevent mildew and more light for photosynthesis.
Benefits of Spacing
A number of studies conducted in India on flower yielding plants grown for essential oils such as Rosa Damascena have demonstrably established the growth enhancing benefits of spacing, pruning and growth hormones. The results of these tests conducted in the 1980s have shown that pruning and spacing can substantially boost flower yield; 18% to 37% increase was recorded in the experiments. It was also observed that plants treated with a low dose (50ppm) with some type of hormone solution containing auxins or cytokinins
also responded with higher total yields.
This study has demonstrated that yields can be increased with proper spacing and use of some type of growth promoter. But how much space should be allowed between plants for the best results? The rule of thumb is that for plants less than three feet tall, each plant should be minimum 18 inches apart and a maximum of 30 inches apart. For anything more than this amount of space, the law of diminishing returns sets in.
Tips for Starting out Plants
The following are some tips for preparing and planting your crop:
1. Plant cuttings right away on arrival. Plan ahead; don’t wait for the cuttings to arrive and then prepare for transplanting. You will waste valuable time getting things into place; meanwhile the plants and the cuttings will begin to loose vigor and wilt. Keep your soil, growing media, etc. ready at hand.
2. Smokers would do well to thoroughly wash their hands or use latex gloves.
3. Make sure your plants are adequately spaced. Plants grown too close to one another are weaker and more likely to fall prey to a host of diseases besides being less resistant to pests. Weaker plants are slower to grow and reach maturity; they yield less fruit or flowers.
4. Cuttings should be exposed to weak or diffused light before being introduced to full HID lighting. The lights should also be positioned not less than 3-4 feet above the new plants or seedlings.
5. Begin on a regular feed program at the earliest and keep to the manufacturer’s recommended level for new cuttings. Formulas used should contain the nitrogen (N) as the nitrate form of nitrogen and not urea or ammonia.
6. Night temperatures should ideally be maintained between 68 deg F (20 deg. F) to 80 deg F during the day. Extremes of temperature cause much harm to plants especially at the starting phase.
Wednesday, November 28, 2007
Thursday, November 8, 2007
Water Quality Considerations in Hydroponics
Water quality is an important determinative factor in hydroponics cultivation. Water is the basic ‘carrier’ in hydroponics as it dissolves and transports nutrients for plants. However, water also dissolves a lot of impurities that can be harmful to plants. These impurities cannot be easily detected visually, and it is all too easy to be misled into making wrong assumptions about the purity of water from the clarity of a sample.
Fortunately, solutions to water quality problems, in the majority of cases, are simple and do not involve complicated methods and techniques. Even small growers can use some simple and proven techniques to effectively solve their water quality problems. The types of water quality problems that growers will likely face depends on the water source from which they draw water for their hydroponics garden.
Poor water quality can lead to a number of plant growth problems including stunted growth, mineral toxicity or deficiency symptoms, build up of unwanted elements in plant tissue, bacterial contamination, etc. Though causes of poor water quality are numerous and varied some of the more frequently encountered of these are
1. Chlorination
Chlorination is the most extensively adopted measure to control bacterial contamination of water supplies in cities, towns and other urban centers. In hydroponics cultivation, the use of chlorine by growers to kill pathogens in their water has caused problems in a number of instances. It was found that this happened due high levels of active chlorine in the water used to make nutrient solution. Chlorinated water sources need to be aerated in a ‘holding tank’ for 48-72 hours (depending on the initial concentration), with good ventilation during which time the active chlorine levels fall to below 1ppm, a safe level for the plant’s root systems. Chlorine in nutrient solution water is known to cause damage to several crops especially to sensitive crops such as lettuce, salad greens, strawberries and others.
2. Unwanted minerals
Water being an excellent solvent dissolves a large number of substances including minerals. While some of these are beneficial, others like sodium, for instance, are quite harmful. Plants do not require sodium and sodium chloride if present in water can cause problems even in small quantities. Sodium can be very harmful especially in re-circulating systems. Plants differ widely in their sensitivity to sodium; some plants like tomatoes can tolerate much higher levels of sodium than other plants such as lettuce. Sodium needs to be kept below 80 ppm for healthy growth of most plants, but below 30 ppm for plants such as lettuce.
Magnesium, calcium, potassium, sulfur, nitrates and trace elements such as boron, copper, manganese and zinc may be present in water from various water sources. This can be taken care of in most cases by suitably adjusting the nutrient formulas to factor in the presence of these elements thus preventing accumulation and toxicities in the water supply. The presence of trace elements can be more troublesome and may require demineralization and dilution of the water source with pure water supply when using in nutrient solutions.
3. Microbial or pathogen contamination
Water from sources such as wells, ponds streams etc. often contains organisms that should be removed before the water can be used in nutrient formulations. The most common of these ‘pathogens’ is Pythium, which can attack plants when present in sufficient spore concentration. Growers have successfully used chlorination as a line of defense against these pathogens, but it requires that the chlorinated water be held for a few days to allow to the concentration of chlorine to drop to levels tolerable to plants. Hydrogen Peroxide can also be used to kill pathogens such as Fusarium wilt and Pythium in water and nutrient solutions.
4. Iron and Iron bacteria
Iron in the form of iron hydroxide is usually present in water from ground water sources near areas with deposits of iron sand or iron ores. The iron hydroxide in water, though not directly harmful to plants presents a number of problems due to the blockages it causes in various components of the system. These blockages if not removed, from an ideal medium for growth of iron bacteria, which consume a variety of elements that are provided for plant growth in hydroponics systems. Iron hydroxide removal methods include aeration and settling or flocculation with different agents. Iron bacteria can be removed by sterilization of the water or nutrient solution.
5. Hard water sources
Water is termed ‘hard’ when it contains substantial amounts dissolved calcium bicarbonate and other elements. When in contact with pipes and equipment the calcium bicarbonate changes to insoluble calcium carbonate also known as lime scale. Hard water forms scale in irrigation pipes, heating elements and pumps causing severe blockages. Computerized water conditioner units similar to the ones used in domestic water supplies can be used to eliminate scaling problems in hydroponics systems.
6. Herbicides
Cases of herbicide contamination of ground water sources and even municipal water supplies are not unknown. Herbicide contamination manifests as damage to sensitive crops such as tomatoes. Activated carbon filtration can help reduce damage but care must be taken to replace the carbon often enough to enable it to retain its efficiency.
Summary
Pure, clean water is essential for healthy plant growth and growers can give the best start to their plants by investing some time and effort in ensuring water quality. Water quality problems are often easy to solve provided they are properly identified. The best approach is to be proactive about water quality as assumptions based on water clarity, absence of visible contamination etc. may be quite misleading.
Fortunately, solutions to water quality problems, in the majority of cases, are simple and do not involve complicated methods and techniques. Even small growers can use some simple and proven techniques to effectively solve their water quality problems. The types of water quality problems that growers will likely face depends on the water source from which they draw water for their hydroponics garden.
Poor water quality can lead to a number of plant growth problems including stunted growth, mineral toxicity or deficiency symptoms, build up of unwanted elements in plant tissue, bacterial contamination, etc. Though causes of poor water quality are numerous and varied some of the more frequently encountered of these are
1. Chlorination
Chlorination is the most extensively adopted measure to control bacterial contamination of water supplies in cities, towns and other urban centers. In hydroponics cultivation, the use of chlorine by growers to kill pathogens in their water has caused problems in a number of instances. It was found that this happened due high levels of active chlorine in the water used to make nutrient solution. Chlorinated water sources need to be aerated in a ‘holding tank’ for 48-72 hours (depending on the initial concentration), with good ventilation during which time the active chlorine levels fall to below 1ppm, a safe level for the plant’s root systems. Chlorine in nutrient solution water is known to cause damage to several crops especially to sensitive crops such as lettuce, salad greens, strawberries and others.
2. Unwanted minerals
Water being an excellent solvent dissolves a large number of substances including minerals. While some of these are beneficial, others like sodium, for instance, are quite harmful. Plants do not require sodium and sodium chloride if present in water can cause problems even in small quantities. Sodium can be very harmful especially in re-circulating systems. Plants differ widely in their sensitivity to sodium; some plants like tomatoes can tolerate much higher levels of sodium than other plants such as lettuce. Sodium needs to be kept below 80 ppm for healthy growth of most plants, but below 30 ppm for plants such as lettuce.
Magnesium, calcium, potassium, sulfur, nitrates and trace elements such as boron, copper, manganese and zinc may be present in water from various water sources. This can be taken care of in most cases by suitably adjusting the nutrient formulas to factor in the presence of these elements thus preventing accumulation and toxicities in the water supply. The presence of trace elements can be more troublesome and may require demineralization and dilution of the water source with pure water supply when using in nutrient solutions.
3. Microbial or pathogen contamination
Water from sources such as wells, ponds streams etc. often contains organisms that should be removed before the water can be used in nutrient formulations. The most common of these ‘pathogens’ is Pythium, which can attack plants when present in sufficient spore concentration. Growers have successfully used chlorination as a line of defense against these pathogens, but it requires that the chlorinated water be held for a few days to allow to the concentration of chlorine to drop to levels tolerable to plants. Hydrogen Peroxide can also be used to kill pathogens such as Fusarium wilt and Pythium in water and nutrient solutions.
4. Iron and Iron bacteria
Iron in the form of iron hydroxide is usually present in water from ground water sources near areas with deposits of iron sand or iron ores. The iron hydroxide in water, though not directly harmful to plants presents a number of problems due to the blockages it causes in various components of the system. These blockages if not removed, from an ideal medium for growth of iron bacteria, which consume a variety of elements that are provided for plant growth in hydroponics systems. Iron hydroxide removal methods include aeration and settling or flocculation with different agents. Iron bacteria can be removed by sterilization of the water or nutrient solution.
5. Hard water sources
Water is termed ‘hard’ when it contains substantial amounts dissolved calcium bicarbonate and other elements. When in contact with pipes and equipment the calcium bicarbonate changes to insoluble calcium carbonate also known as lime scale. Hard water forms scale in irrigation pipes, heating elements and pumps causing severe blockages. Computerized water conditioner units similar to the ones used in domestic water supplies can be used to eliminate scaling problems in hydroponics systems.
6. Herbicides
Cases of herbicide contamination of ground water sources and even municipal water supplies are not unknown. Herbicide contamination manifests as damage to sensitive crops such as tomatoes. Activated carbon filtration can help reduce damage but care must be taken to replace the carbon often enough to enable it to retain its efficiency.
Summary
Pure, clean water is essential for healthy plant growth and growers can give the best start to their plants by investing some time and effort in ensuring water quality. Water quality problems are often easy to solve provided they are properly identified. The best approach is to be proactive about water quality as assumptions based on water clarity, absence of visible contamination etc. may be quite misleading.
Tuesday, November 6, 2007
The Role & Measures of Nutrients in Plant Growth
Environment plays a very important role in plant growth upto a point. Once optimal environmental levels have been achieved in the hydroponics grow room, however, it is the quality of nutrition that determines crop quality and output. The following background information will be useful in understanding of the role of nutrients in hydroponics cultivation.
Nitrogen
Plants absorb nitrogen from fertilizers in both Nitrate (NO3) and ammonium (NH4) forms. Both ammonium and nitrate forms are available in the standard fertilizer mix supplied. It should be noted however, that ammonium levels should be significantly lower than nitrate levels with a safe level being 10 to 20 times nitrogen available in the Nitrate form vis-à-vis the Ammonium form.
Ammonium is readily available to plants and can build up to toxic levels in plant tissue if it is not assimilated for growth. Besides, the Nitrogen from Ammonium is difficult to leach away once it is in plant tissue. It is therefore important too ensure that ammonium content in the nutrients is carefully regulated.
Over supply of fertilizers with high levels of Ammonium nitrogen manifests as distorted and dark growth starting at the plant’s growing tip. The imbalance may also lead to symptoms of other nutrient deficiencies despite these nutrients being supplied in the correct amounts. This is because of the nutrient imbalance that is created. Higher nitrogen levels are required during vegetative/green growth phases. After proper rooting of cuttings, nitrogen levels can be increased from ¼ strength to full strength over 10 to 14 days. Over application of nitrogen causes delayed flower and fruit development. Nitrogen levels at the time of rooting of cuttings should be around 100 ppm and may be increased to +250 ppm for aggressive growth under optimal conditions. Light conditions can make a difference to the Nitrogen to Potassium ratio, which can be about 1:1 under higher light conditions, while under low light conditions it may be as high as 1:5.
Phosphorus
Plants require the phosphorus content of the nutrient mix to be high during the flowering/fruiting phase of their life cycle. At other times amounts between 15 to 30 ppm are quite adequate for most crops. Over supply of phosphorus will be harmful during these stages as it will lead to imbalances of iron and calcium and even zinc. Iron and zinc have an association with the greenness of plants, phosphorus levels should therefore be increased only with corresponding increases in levels of calcium, iron and zinc. Calcium levels should be maintained at 1.5:1 ratio with phosphorus. Most commercial calcium nutrient formulations include the right proportions of trace elements to cover flowering/fruiting requirements. Phosphorous levels may be increased to 250 ppm during the peak phase maintaining important ratios such as calcium and micro-nutrients.
Potassium
Potassium is required in root development and also for the ripening process of flowers, fruits, and seeds. Potassium levels can be increased during the flowering/fruiting phase to harvest a heavy, colorful and firm produce. High potassium levels in some crops help increase resistance foliar diseases such as powdery mildew.
Under low lighting growth conditions higher potassium to nitrogen ratios in the range of 3:1 helps healthy vegetative growth. Under brighter the same nutrient proportion may be closer to 1:1 to stimulate vigorous green growth. Most plants do well on potassium levels in the range of 100 to +400 ppm.
Calcium
Calcium is an important component of the cell walls of plants and is also plays an important role in the processes of cell division. It requires to be maintained in a ratio to phosphorus and is best applied in greater amounts 1.5X the level of potassium. The calcium magnesium ratio is also important and should be maintained at 3:1. For instance with 150 ppm calcium levels in a nutrient solution, magnesium levels should be maintained at around 50 ppm.
Magnesium
Magnesium is associated with keeping the plant “green” and is a carrier molecule for certain plant processes. Indoor crops will generally benefit from elevated magnesium levels. Reports on the use of elevated levels of Magnesium have been positive with growers harvesting firmer flowers and fruits. Hydroponics calcium formulations often contain additional amounts of magnesium. It should be noted however, that magnesium levels should be maintained around 1:3 ratio to calcium.
Other Nutrients
In addition to the above nutrients, that constitute the main macro-nutrients that plants need to obtain from the nutrient formulations, there are other macro and micro-nutrients that are vital to various plant processes. While plants use macro-nutrients in large or appreciable quantities, the micro-nutrients are required in trace amounts Plants absorb carbon, hydrogen and oxygen from the air and water. The following table lists various nutrients essential for plant nutrition and the different plant processes they serve.
Macronutrients
Carbon--> Organic compounds formation
Oxygen--> Energy release
Hydrogen--> Water formation
Nitrogen--> Chlorophyll, Proteins formation
Phosphorus--> Photosynthesis
Potassium--> Enzyme activity, starch formation, sugar formation
Calcium--> Cell growth, component of cell wall
Magnesium--> Enzyme activation
Sulfur--> Amino acids and proteins formation
Micronutrients
Boron--> Reproduction
Chlorine--> Root growth
Copper--> Enzyme activation
Iron--> Photosynthesis
Manganese--> Enzyme activation
Sodium--> Water movement
Zinc--> Enzymes and auxins component
Molybdenum--> Nitrogen Fixation
Nickel--> Nitrogen Liberation
Cobalt--> Nitrogen Fixation
Silicon--> Cell wall toughnening
Nitrogen
Plants absorb nitrogen from fertilizers in both Nitrate (NO3) and ammonium (NH4) forms. Both ammonium and nitrate forms are available in the standard fertilizer mix supplied. It should be noted however, that ammonium levels should be significantly lower than nitrate levels with a safe level being 10 to 20 times nitrogen available in the Nitrate form vis-à-vis the Ammonium form.
Ammonium is readily available to plants and can build up to toxic levels in plant tissue if it is not assimilated for growth. Besides, the Nitrogen from Ammonium is difficult to leach away once it is in plant tissue. It is therefore important too ensure that ammonium content in the nutrients is carefully regulated.
Over supply of fertilizers with high levels of Ammonium nitrogen manifests as distorted and dark growth starting at the plant’s growing tip. The imbalance may also lead to symptoms of other nutrient deficiencies despite these nutrients being supplied in the correct amounts. This is because of the nutrient imbalance that is created. Higher nitrogen levels are required during vegetative/green growth phases. After proper rooting of cuttings, nitrogen levels can be increased from ¼ strength to full strength over 10 to 14 days. Over application of nitrogen causes delayed flower and fruit development. Nitrogen levels at the time of rooting of cuttings should be around 100 ppm and may be increased to +250 ppm for aggressive growth under optimal conditions. Light conditions can make a difference to the Nitrogen to Potassium ratio, which can be about 1:1 under higher light conditions, while under low light conditions it may be as high as 1:5.
Phosphorus
Plants require the phosphorus content of the nutrient mix to be high during the flowering/fruiting phase of their life cycle. At other times amounts between 15 to 30 ppm are quite adequate for most crops. Over supply of phosphorus will be harmful during these stages as it will lead to imbalances of iron and calcium and even zinc. Iron and zinc have an association with the greenness of plants, phosphorus levels should therefore be increased only with corresponding increases in levels of calcium, iron and zinc. Calcium levels should be maintained at 1.5:1 ratio with phosphorus. Most commercial calcium nutrient formulations include the right proportions of trace elements to cover flowering/fruiting requirements. Phosphorous levels may be increased to 250 ppm during the peak phase maintaining important ratios such as calcium and micro-nutrients.
Potassium
Potassium is required in root development and also for the ripening process of flowers, fruits, and seeds. Potassium levels can be increased during the flowering/fruiting phase to harvest a heavy, colorful and firm produce. High potassium levels in some crops help increase resistance foliar diseases such as powdery mildew.
Under low lighting growth conditions higher potassium to nitrogen ratios in the range of 3:1 helps healthy vegetative growth. Under brighter the same nutrient proportion may be closer to 1:1 to stimulate vigorous green growth. Most plants do well on potassium levels in the range of 100 to +400 ppm.
Calcium
Calcium is an important component of the cell walls of plants and is also plays an important role in the processes of cell division. It requires to be maintained in a ratio to phosphorus and is best applied in greater amounts 1.5X the level of potassium. The calcium magnesium ratio is also important and should be maintained at 3:1. For instance with 150 ppm calcium levels in a nutrient solution, magnesium levels should be maintained at around 50 ppm.
Magnesium
Magnesium is associated with keeping the plant “green” and is a carrier molecule for certain plant processes. Indoor crops will generally benefit from elevated magnesium levels. Reports on the use of elevated levels of Magnesium have been positive with growers harvesting firmer flowers and fruits. Hydroponics calcium formulations often contain additional amounts of magnesium. It should be noted however, that magnesium levels should be maintained around 1:3 ratio to calcium.
Other Nutrients
In addition to the above nutrients, that constitute the main macro-nutrients that plants need to obtain from the nutrient formulations, there are other macro and micro-nutrients that are vital to various plant processes. While plants use macro-nutrients in large or appreciable quantities, the micro-nutrients are required in trace amounts Plants absorb carbon, hydrogen and oxygen from the air and water. The following table lists various nutrients essential for plant nutrition and the different plant processes they serve.
Macronutrients
Carbon--> Organic compounds formation
Oxygen--> Energy release
Hydrogen--> Water formation
Nitrogen--> Chlorophyll, Proteins formation
Phosphorus--> Photosynthesis
Potassium--> Enzyme activity, starch formation, sugar formation
Calcium--> Cell growth, component of cell wall
Magnesium--> Enzyme activation
Sulfur--> Amino acids and proteins formation
Micronutrients
Boron--> Reproduction
Chlorine--> Root growth
Copper--> Enzyme activation
Iron--> Photosynthesis
Manganese--> Enzyme activation
Sodium--> Water movement
Zinc--> Enzymes and auxins component
Molybdenum--> Nitrogen Fixation
Nickel--> Nitrogen Liberation
Cobalt--> Nitrogen Fixation
Silicon--> Cell wall toughnening
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