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All About Hydroponics


Hydroponic Gardening is Simple and Easy

Hydroponics is basically growing plants without soil. It is a more efcient way to provide food and water to your plants. Plants don't use soil-they use the food and water that are in the soil. Soil's funcfion is to supply nutrients and to anchor the plants' roots.

In a hydroponic garden, you provide your plants with a complete nutrient formula and an inert growing medium to anchor your plants' roots so they have easier access to the food and water.

Because the food is dissolved in water, it goes directly to the roots. Plants grow faster and are ready for harvest sooner. You can grow more plants in the same space as you can with a soil garden, and since there's no soil, there's no worry about soil-borne diseases or pests- and no weeding.


Grow Like the Pros
Hydroponic garden systems give you all the advantages of the high-performance technology and professional grade materials used by commercial growers, all in an easy-to use package. Each system we offer is complete: there's nothing extra to buy or build - all you need are seeds and water.

Affordable, Energy Efficient, Easy to Use
High Intensity Grow Lights are easy for home gardeners to use. They come pre-wired and are rated at 1 20 volts (your normal home current), so they're compatible with any standard home outlet. Just hang them from a simple ceiling hook, plug them in, and start growing.

Grow Prize-Winning Plants Year Round
With sun-like high intensity lighting, you can turn any room of your home into a virtual greenhouse. Grow any plant, anywhere, any time you choose! Imagine harvesting fresh tomatoes, picking peppers or growing a rare orchid in your basement -these lights make it possible.

A single system can easily provide all the light needed to cover anywhere from a 1'x 2' area up to a 12'x12' area, depending on what size wattage system meets your growing needs.

100% CUSTOM You..
Designing Your Perfect System

Full spectrum fluorescents and lighting systems make it easy to grow the garden you want- whether you're starting seedlings for your outdoor spring garden or growing your favorite plants indoors. Use our lower wattage fluorescents for seedlings, cuttings and low light plants like African violets. Higher wattage fluorescent grow lights provide a n excellent starter light for year-round gardening indoors.

Choosing the Right System
Choosing a system is the first step in a successful hydroponic gardening experience. Consider your available space, lighting, budget, and time constraints before purchasing any equipment or settling on a unit to build yourself. Also think about what you want to grow, whether you may want to expand, and recurring costs.

The simplest way to start is with a passive system. These use a wicking material to draw nutrients up to the roots, or the root tips are suspended in a stationary solution with the main portion of the rootball hanging in the air. Passive systems are affordable and easy to build yourself. They are best suited for smaller plants.

Active systems are best for larger plants and gardens. An active system uses a pump and timer to flow nutrients around the plant's roots and to provide aeration. It costs more, but is more efficient and requires less attention, since the pump and timer handle everything automatically.

Once you've looked at passive vs. active systems, you'll need to choose, between media-based and water culture systems.

Media-based systems such as ebb and flow (flood-and-drain), top feed (drip), or bottom-feed systems rely on a growing medium to support the plants and hold nutrient solution around their roots. Most operate o n timers, alternately wetting the medium to wash out salts and replenish nutrients and then draining so the plants can draw in atmospheric oxygen. Setup is more complex, costs are higher, and media needs to be replaced occasionally. These systems need to be protected from power outages, which can leave vulnerable roots high and dry if the pump stops functioning. 0 n the other hand, these systems are super efficient, since nutrients are recycled back into the reservoir, and use of timers means they need less attention from you.

Water culture systems usually operate without media. Plants are anchored in a plank that floats o n the reservoir, suspending the roots in the nutrient solution. This kind of system is simple and inexpensive to setup and is great for water-loving plants, though special care must be taken if you want to use it with large plants. You can use rockwool cubes or small amounts of gravel to anchor plants like tomatoes and cucumbers that get top heavy when they start to bear fruit. You can also use plastic flaps, foam rings, fiber cups, o r plastic collars for plant support, or tie plants to a trellis.

During photosynthesis, plants use carbon dioxide (CO), light, and hydrogen (usually water) to produce carbohydrates, which is a source of food. Oxygen is given off in this process as a by-product. Light is a key variable in photosynthesis.

Electronic devices manufactured to measuring nutrient solution are quite sophisticated and use the latest microprocessor technology. To understand how these devices work, you have to know that pure water doesn't conduct electricity. But as salts are dissolved into the pure water, electricity begins to be conducted. An electrical current will begin to flow when live electrodes are placed into the solution. The more salts dissolved, the a stronger the salt solution and the more electrical current will flow. This current flow is connected to special electronic circuitry that allows you to determine the strength of the nutrient solution.

The scale used to measure nutrient strength is electrical conductivity (EC) or conductivity factor (CF). The CF scale is most commonly used in hydroponics. lt spans from 0 to more than 100 CF units. The part of the scale generally used by home hydroponic gardeners spans 0-100 CF units. The part of the scale generally used by commercial or large-scale hydroponic growers is from 2 to 4 CF (strength for growing watercress and some fancy lettuce) to as high as approximately 35 CF for fruits, berries, and ornamental trees. Higher CF values are used by experienced commercial growers to obtain special plant responses and for many of the modern hybrid crops, such as tomatoes and some peppers. Most other plant types fall between these two figures and the majority is grown at 13-25 CF. 

When a seed first begins to grow, it is germinating. Seeds are germinated in a growing medium. Several factors are involved in this process. First, the seed must be active, alive, and not in dormancy. Most seeds have a specific temperature range that must be achieved. Moisture and oxygen must be present. And some seeds need specified levels of light or darkness. Check the specifications of seeds to see their germination requirements.

The first two leaves that sprout from a seed are called the seed leaves, or cotyledons. These are not the true leaves of a plant. The seed develops these first leaves to serve as a starting food source for the young, developing plant.

Soil is never used in hydroponic growing. Some systems have the ability to support the growing plants, allowing bare roots to have maximum exposure to the nutrient solution. In other systems, the roots are supported by a growing medium. Some types of media also aid in moisture and nutrient retention. Different media are better suited to specific plants and systems. It is best to research all of your options and to get some recommendations for systems and media before making, investing in, or building an operation.

Popular growing media include:
Composted bark
is usually organic and can be used for seed germination or clone propagation.

is a renewable resource made from the pith of a coconut husk. Makes an excellent organic soil amendment and may also be used as a stand-alone hydroponic medium.

Expanded Clay
Pellets are baked in a very hot oven, which causes them to expand, creating a porous end product.

comes in many types, and any type can be used. It can add minerals to nutrient, so always make sure it's clean.

is an artificial, foam-based material commonly known from its use as a n arrangement base in the floral industry. Used for seed germination or clone propagation.

Peat moss
is carbonized and compressed vegetable matter that has been partially decomposed.

Perlite is made by mining volcanic glass from lava flows and heating it in furnaces to a high temperature, causing the small amount of moisture inside to expand. This converts the hard glass into small, sponge-like kernels.

Pumice is a glassy material that is formed by volcanic activity. Pumice is light weight due to its large number of cavities produced by the expulsion of water vapor at a high temperature as lava surfaces.

Rock wool
is created by melting rock at a high temperature and then spinning it into fibers. Sand varies in composition and is usually used in conjunction with another medium.

Vermiculite is similar to perlite,
except that it has a relatively high cation exchange capacity - meaning it can hold nutrients for later use.
There are a number of other materials that can (and are) used as growing media. Hydroponic gardeners tend to be an innovative and experimental group.

The apparatuses used in hydroponic growing are many and varied. There are two basic divisions between systems: media-based and water culture. Also, systems can be either active or passive. Active systems use pumps and usually timers and other electronic gadgets to run and monitor the operation. Passive systems may also incorporate any number of gadgets. However, they do not use pumps and may rely on the use of a wicking agent to draw nutrient to the roots.

As their name implies- use some form of growing medium. Some popular media-based systems include ebb-and-flow (also called flood-and-drain), run-to-waste, drip-feed (or top-feed), and bottom-feed. Water culture systems do not use media. Some popular water culture systems are raft (also called floating and raceway), nutrient film technique (NFT), and aeroponics.

Think of a plant as a well-run factory that takes delivery of raw materials and manufactures the most wondrous products. Just as a factory requires a reliable energy source to turn the wheels of its machinery, plants need energy in order to grow.

Usually, natural sunlight is used for this important job. However, during the shorter and darker days of winter, many growers use artificial lights to increase the intensity of light (for photosynthesis) or to expand the daylight length. While the sun radiates the full spectrum (wavelength or color of light) suitable for plant life, different types of artificial lighting are selected for specific plant varieties and optimum plant growth characteristics. Different groups of plants respond in physically different ways to various wavelengths of radiation. Light plays a n extremely important role in the production of plant material. The lack of light is the main inhibiting factor in plant growth. If you reduce the light by 10 percent, you also reduce crop performance by 10 percent. Light transmission should be your major consideration when purchasing a growing structure for a protected crop. Glass is still the preferred material for covering greenhouses because, unlike plastic films and sheeting, its light transmission ability is indefinitely maintained. N o gardener can achieve good results without adequate light. If you intend to grow indoors, avail yourself of some of the reading material that has been published on this subject. lf you are having trouble growing good plants, then light is the first factor to question. -

A large part of the success in growing hydroponically is planning where to place the plants. Grow plants that have similar growing requirements in the same system. Placing your system 1-2 feet away from a sunny window will give the best results for most herbs and vegetables. Even your regular house lights help the plants to grow. Make sure that all of the lights are out in your growing area during the night. Plants need to rest a minimum of 4 hours every night. lf your plants start to get leggy (too tall and not very full), move the system to a spot that has more sun. 0nce you find a good growing area, stick to it. Plants get used to their home location. It may take some time to get used to a new place.

Plants need around 16 mineral nutrients for optimal growth. However, not all these nutrients are equally important for the plant. Three major rninerals - nitrogen (N), phosphorus (P), and potassium (K)-are used by plants in large amounts. These three minerals are usually displayed as hyphenated numbers, like "15-30-15," on commercial fertilizers. These numbers correspond to the relative percentage by weight of each of the major nutrients-known as macron nutrients - N, P, and K. Macronutrients are present in large concentrations in plants. All nutrients combine in numerous ways to help produce healthy plants. Usually, sulfur (S), calcium (Ca), and magnesium (Mg) are also considered macronutrients. These nutrients play many different roles in plants. Here are some of their dominant functions;

Nitrogen (N)-promotes development of new leaves

Phosphorus (P)-aids in root growth and blooming

Potassium (K)-important for disease resistance and aids growth in extreme temperatures

Sulfur (S)-contributes to healthy, dark green color in leaves

Calcium (Ca)-promotes new root and shoot growth

Magnesium (Mg)-chlorophyll, the pigment that gives plants their green color and absorbs sunlight to make food, contains a Mg ion.


Boron (B), copper( Cu), cobalt (Co), iron (Fe), manganese (M n), molybdenum (Mo), and zinc (Zn) are only present in minute quantities in plants and are known as micronutrients. Plants can usually acquire adequate amounts of these elements from the soil, so most commercial fertilizers don't contain all of the micronutrients. Hydroponic growers, however, don't have any soil to provide nutrients for their plants. Therefore, nutrient solution marketed for hydroponic gardening contains all the micronutrients.

In hydroponics, nutrient solution -sometimes just referred to as "nutrient" -is used to feed plants instead of plain water. This is due to the fact that the plants aren't grown in soil. Traditionally, plants acquire most of their nutrition from the soil. When growing hydroponically, you need to add all of the nutrients a plant needs to water. Distilled water works best for making nutrient. Hydroponic supply stores have a variety of nutrient mixes for specific crops and growth cycles. Always store solutions out of direct sunlight to prevent any algae growth. See also conductivity, macronutrients, and micronutrients. Nutrient solution is not like regular water, so you must be careful where you dispose of it. Even organic nutrients and fertilizers can cause serious imbalances in aquatic ecosystems. lf you do not live near a stream, river, lake or other water source, it is fine to use old nutrient on outdoor plants and lawn. Another possibility is to use it o n houseplants. However, if you live within 1,500 feet of a viable water source, do not use your spent nutrient in the ground.

The ends of a plant's roots aren't open-ended like a drinking straw and they definitely don't suck up a drink of water or nutrients. Science is still seeking a complete understanding of osmosis, so to attempt a full and satisfactory description of all that's involved would b e impossible. However, we can understand the basic osmotic principle as it relates to plants. First, consider a piece of ordinary blotting paper, such as the commonly used filter for home coffee machines. The paper might appear to be solid. However, if you apply water to one side of it, you'll soon see signs of the water appearing on the opposite side. The walls of a feeding root act in much the same way. lf you pour water onto the top of the filter paper, gravity allows the water to eventually drip through to the bottom side. Add the process of osmosis, and water applied to the bottom side drips through to the top.

With plants, this action allows water and nutrients to pass through the root walls from the top, sides, and bottom. Osmosis is the natural energy force that moves elemental ions through what appears to be solid material. A simplistic explanation for how osmosis works, although not 100 percent accurate, is that the stronger ion attracts the weaker through a semi permeable material. So, the elements within the cells that make u p plant roots attract water and nutrients through the root walls when these compounds are stronger than the water and nutrients applied to the outside of the roots.

It then follows that if you apply a strong nutrient to the plant roots-one that's stronger than the compounds inside of the root-that the reverse action is likely to occur! This process is called reverse osmosis. Many gardeners have at some time committed the sin of killing their plants by applying too strong a fertilizer to their plants, which causes reverse osmosis. Instead of feeding the plant, they have actually been dragging the life force out of it.

Understanding how osmosis works, the successful grower can wisely use this knowledge to promote maximum uptake of nutrients into the plants without causing plant stress-or worse, plant death-from over fertilizing. All plants have a different osmotic requirement or a n optimum nutrient strength. -

As a result of the process of photosynthesis, oxygen( 0) is given off by plants. Than, at night, when light isn't available for photosynthesis, this process is reversed. At night, plants take in oxygen and consume the energy they have stored during the day.

Even though hydroponic gardeners dodge a large number of plant problems by eschewing soil (which is a home to any number of plant enemies), pests and diseases still manage to wreak havoc from time to time. Botrytis, Cladosporium, Fusarium, and Verticillium cover most of the genera of bacteria that can threaten your plants. The insects that can prove annoying include aphids, caterpillars, cutworms, fungus gnats, leaf miners, nematodes, spider mites, thrips, and whiteflies.

Here are a few good ways to prevent infestation and infection:

Always maintain a sanitary growing environment

Grow naturally selected disease- and pest-resistant plant


Keep your growing area properly ventilated and at the

correct temperatures for your plants

Keep a close eye on your plants so if a problem does occur,

you can act quickly

With insects, sometimes you can pick off and crush any large ones. Or yo a can try to wash the infected plants with water or a mild soap solution (such as Safer Soap).

If a problem gets out of control, it may be necessary to apply a biological control in the form of a spray. Research which product will work best in your situation. Always follow the instructions on pesticides very closely.

Alternatively, there are a number of control products o n the market today that feature a botanical compound or an ingredient that has been synthesized from a plant material.

Over the last few years, researchers from all around the world have started to take a much closer look at any compounds present in the plant kingdom that might hold the answer to our pest and disease control problems. Many companies have even switched from producing synthetic pesticides to copying nature by synthesizing naturally occurring compounds in a laboratory setting. Extracts of willow, cinnamon, grapefruit, garlic, bittersweet, lemon grass, derris, eucalyptus, and tomato have been helpful in controlling diseases and pests.

The pH of a nutrient solution is a measurement of its relative concentration of positive hydrogen ions. Negative hydroxyl ions are produced by the way systems filter and mix air into the nutrient solution feeding plants. Plants feed by an exchange of ions. As ions are removed from the nutrient solution, pH rises. Therefore, the more ions that are taken up by the plants, the greater the growth. A solution with a pH value of 7.0 contains relatively equal concentrations of hydrogen ions and hydroxyl ions. When the pH is below 7.0, there are more hydrogen ions than hydroxyl ion. Such a solution "acidic." When the pH is above 7.0, there are fewer hydrogen ions than hydroxyl ions. This means that the solution is "alkaline."

Test the pH level of nutrient with a kit. These kits are available at local chemistry, hydroponic, nursery, garden  supplier, or swimming pool supply stores. Also test the pH level of your water before adding any nutrients. If your solution is too alkaline add soma acid. Although such conditions rarely occur, sometimes you may have to reduce the level of acidity by making the solution more alkaline by adding potassium hydroxide (or potash) to the solution in small amounts until it is balanced once again.

Plants need to absorb many necessary nutrients from the nutrient solution or-in the case of traditional agriculture-the soil. However, plants can create some of their own food. Plants use the process of photosynthesis to create food for energy. Carbohydrates are produced from carbon dioxide (C02) and a source of hydrogen (H)-such as water-in chlorophyll containing plant cells when they are exposed to light. This process results in the production of oxygen (0).

Every now and again, you are sure to run into a problem with your plants. This is just a simple fact of any type of gardening. The key is to act quickly, armed with quality knowledge.

Nitrogen deficiency will cause yellowing of the leaves, especially in the older leaves. The growth of new roots and shoots is stunted. In tomatoes, the stems may take o n a purple hue. A phosphorous deficiency is usually associated with dark green foliage and stunted growth. The stems may appear purple. But since the leaves don't yellow as they do in nitrogen deficiency, the whole, plant can take on a purplish green color. Iron deficiency results in yellowing between the leaf veins. In contrast to nitrogen deficiency, the yellowing first appears in the younger leaves. After a prolonged absence of iron, the leaves can turn completely white.

This condition can be caused by environmental factors or disease (usually caused by Fusarium, alarge genus of filamentous fungi widely distributed in soil and in association with plants). Nutrient and mediatemperature can be adjusted to remedy wilt. However, if Fusarium have taken hold, the chances that your plants will survive are slim. If wilting is duet o environmental causes try to spray the plants and roots with cool, clean water to rejuvenate them. lf this hasn't helped them by the next day, try it again. If the plants respond, top-oft the nutrient solution and check the pH. If plants don't respond to the misting, empty the tank, move it to a shadier spot, and refill with cool, fresh nutrient solution. Don't reuse the old solution - start with fresh water and nutrients.

I have seen tomato plants that have been so dehydrated due to a nutrient supply blockage that they were lying flat and for all the world looked stone-cold dead. When the nutrient flow resumed and the plants were given the less stressful environment of nighttime, they rebounded so well that l wondered if l had dreamed the previous day's "disaster." The moral of this story is to always give plants a chance to revive, even when the situation looks hopeless. 

Plants can be propagated by a number of methods. Growers can let a plant go to seed, collect the seeds, and then start the cycle over again (see germination). Another method is to take stem cuttings, which is also known as cloning (because you are creating an exact copy of the parent plant). Although this process won't work with all plants, it is a highly effective technique. Simply cut off a side shoot or thet op of the main shoot just below a growth node. Make sure that there are at least two growth nodes above the cut. Remove any of the lower leaves near the base of the new plant. This cutting can then be rooted by placing it in water or in a propagation medium ( perlite works well) that is kept moist. The use of some rooting hormone can help your chances of success.

Remove any discolored, insect-eaten, or otherwise sick-looking leaves from plants. Picking off some outer leaves or cutting the top off a plant can help it grow fuller. Use sharp scissors to prune your plants. Sometimes you will want to prune a plant to focus its energy on the remaining shoots. Pruning is an art and should be performed with care. Damaged or dying roots may also need to be pruned from time to time.

Never use soil during any aspect of hydroponics. lf you ever move a plant from a soil-based situation to hydroponics, remove all traces of soil or poking mix from the roots. Soil holds lots of microbes and other organisms and materials that love to grow in and contaminate your hydroponic system. Some of these will actually parasitize your plant and slow its growth. This is another advantage of hydroponic growing: The plant can get on with growing without having to support a myriad of other organisms as happens in conventional soil growing.

Different plants have different germination and growing temperatures. Always make sure that you check each plant's growing requirements-especially minimum and maximum temperature levels. Keep in mind that specific varieties of plants may have different requirements.

Because the water supply is the source of life for your plants, quality is important. All plants rely o n their ability to uptake water freely. Between 80 and 98 percent of this uptake is required for transpiration (loosely compared to perspiration in animals), which allows the plant to produce and somewhat control its immediate microclimate. Plants also need clean, uncontaminated water to produce their own healthy food supply.


AERATION: Supplying soil and roots with air or oxygen. Hydroton is an example of a medium with excellent aeration. In some hydroponic systems, a nutrient solution is aerated by the output of a n air pump.

AEROPONICS: A system in which the roots of a plant are consistently or intermittently misted with fine droplets of nutrient solution.

ACID: Refers to medium or nutrient solution with a low pH; an acidic solution has a pH below 7.

ALKALINE: Refers to medium or nutrient solution with a high pH; any pH over 7 is considered alkaline.

BLOOM BOOSTER, BLOSSOM BOOSTER: Fertilizer high in phosphorus (P) that increases fruit and flower yield.

BORON (B): The function of this micro nutrient is not well understood, but it is suspected that it might aid with synthesis.

BURN: Leaf tips that turn crispy from excess fertilizer and salt burn.

CALCIUM (Ca): Calcium is vital in all parts of plants to promote the translocation of carbohydrates, healthy cell wall structure, strong stems, membrane maintenance and root structure development. Calcium is a macro nutrient.

CARBON DIOXIDE (C02): A colorless, odorless, tasteless gas in the air necessary for plant life. Occurs naturally in the atmosphere at. 03 %.

CHLORINE (CI): This micro nutrient is essential for photosynthesis, where it acts as an enzyme activator during the production of oxygen from water. .

CHLOROSIS: The condition of a sick plant with yellowing leaves due to inadequate formation of chlorophyll Chlorosis is caused by a nutrient deficiency, usually iron o r nitrogen; nutrient deficiencies are themselves often caused by a pH that is out of the acceptable range.

CLONE: A plant produced through asexual reproduction including, but not limited to, cuttings, layering and tissue culture.

CONDITIONING: To soak new Rock wool in an acidic solution to lower the p H from 8.0 to 5.5.

COPPER (Cu): This micro nutrient is an internal catalyst and acts as a n electron carrier; it is also believed to play a role in nitrogen fixation.

DAMPING-OFF FUNGUS: Disease that attacks young seedlings and cuttings, causing stems to rot at the base; over watering is the main cause of damping-off.

DISSOLVED SOLIDS or TOTAL DISSOLVED SOLIDS: The amount of dissolved solids, usually fertilizer salts, that are measured in water in parts per million.

DRIP AERATION: A hydroponic method wherein air pressure from a small air pump is used to percolate nutrient solution out through a ring of feeder tubing which encircles the plant.

DRIP SYSTEM (DRIP EMITTER SYSTEM): A very efficient watering system that employs a main hose with small water emitters. Water is metered out of the emitters, one drop at a time.

EBB-AND-FLOW (or FLOOD and DRAIN): A hydroponic system in which the medium, usually aggregate pebbles, is periodically flooded with nutrient solution and then drained again, feeding and aerating the medium and root system.

FOLIAR FEEDING: Misting plants with fertilizer solution, which is absorbed by pores of a leaf's surface.

FUNGICIDE: A product that destroys or inhibits fungus.

FUNGUS: Any of a major group (Fungi) of saprophytic and parasitic spore-producing organisms usually classified as plants that lack chlorophyll and include molds, rusts, mildews, smuts, mushrooms, and yeasts. Common fungal diseases that attack plants are "damping-off," Botrytis, and powdery mildew.

GERMINATION: The process of causing the initiation and development of a plant from seed.

HARDEN-OFF: To gradually acclimatize a plant to a more harsh environment. A seedling must be hardened-off before planting outdoors.

HORMONE: Chemical substance that controls the growth and development of a plant. Root-inducing hormones help cuttings root.

HYBRID: The offspring from two plants of different breeds, variety or genetic make-up.

HYDRATED LIME: Instantly soluble lime, used to lower the acidity in soils and potting mixes.

HYDROTON: One of several brand names/varieties of clay aggregate medium (also known as LECA for light expanded clay aggregate). It is a lightweight, porous substrate with excellent aeration. Because it does not really wick water effectively, Hydroton and other LECA mediums are favorites in ebb-and-flow and drip hydroponic systems.

HYGROMETER: An instrument for measuring relative humidity in the atmosphere.

IRON (Fe): This micro nutrient acts as a catalyst in the photosynthesis/respiration process, and is essential for the formation of sugars and starches. Iron also activates certain other enzymes.

LEAF CURL: Leaf malformation due to over watering, over fertilization, lack of magnesium, insect or fungus damage or negative tropism.

MACRON NUTRIENTS: The primary nutrients N-P-K or the secondary nutrients magnesium and calcium.

MANGANESE (Mn): This micronutrient activates one or more enzymes in fatty acid synthesis; it also activates the enzymes responsible for DNA and RNA production. Closely associated with copper and zinc, manganese also participates directly in the photosynthetic creation of oxygen from water.

MEDIUM: The substrate or soilless material which supports the plant and absorbs and releases the nutrient solution in hydroponic horticulture.

MICRONUTRIENTS: Also referred to as TRACE ELEMENTS, including S, Fe, M n, B, Mb, An and CU.

MOLYBDENUM (Mo): This micronutrient is essential for nitrogen fixation and nitrate reduction.

NECROSIS: The dying of plant tissue, usually the result of serious nutrient deficiency or pest attack.

NITROGEN (N): Nitrogen is used in various forms to promote rapid vegetative growth, leaf, flower, fruit and seed development, and chlorophyll development; and to increase the protein content in all plants.

NFT (NUTRIENT FILM TECHNIQUE): A hydroponic method in which nutrient is fed into grow tubes or trays in a thin film where the roots draw it up. This "nutrient film" allows the roots to have constant contact with the nutrient and the air layer above at the same time.

NUTRIENT SOLUTION: The mixture of water and water-soluble nutrients which is provided to the plants for nourishment in a hydroponic system.

NUTRIENTS: The elements needed by plants for normal growth and health. The major nutrients (MACRO-NUTRIENTS) are nitrogen (N), phosphorus (P) and potassium (K), but there are numerous MICRONUTRIENTS (also called TRACE ELEMENTS) which also have integral roles in maintaining plant health. A good quality hydroponic nutrient formula will contain all of the major nutrients and micronutrients needed by the vast majority of plants.

NUTRIENTS, SECONDARY: The elements calcium (Ca), magnesium (Mg), and sulphur (S) are usually referred to by this term. They are considered nearly as important as N, P and K micronutrients

PERLITE: 1. Sand or volcanic glass which has been expanded by heat; perlite holds water and nutrients on its many irregular surfaces.
             2. Mineral soil amendment.

pH: A scale from 1 to 14 that measures the acid to alkaline balance of a growing medium (or any other substance). In general, plants grow best in a p H range of 5.5-7.0 is considered ideal. If the p H is not within the acceptable range, -nutrients may not be absorbed to maximum capacity.

PHOSPHORUS (P): Phosphorus promotes and stimulates early growth and blooming and root growth. It hastens maturity and seed growth, and contributes to the general hardiness of plants. Phosphorus is a macronutrient.

PHOTOPERIOD: Day length; the relationship between the length of light and dark in a24-hour period.

PHOTOSYNTHESIS: The process by which plants use light energy to collect carbon dioxide from the atmosphere and convert it to chemical energy in the form of sugar.

POTASSIUM (K): Potassium promotes disease resistance and good development of carbohydrates, starches and sugars, and it increases fruit production. Potassium is a macronutrient.

PROPAGATE: 1. Sexual propagation to produce seed by breeding different male and female flowers. 2. Asexual propagation: to produce plantlets (also known as CLONES) by taking cuttings.

PYRETHRUM: Natural insecticide made from the blossoms of various chrysanthemums.

RESERVOIR: The container in a hydroponic system which holds nutrient solution in reserve for use.

ROCKWOOL: Inert, soilless growing medium consisting of woven, thin strand-like fibers made from molten volcanic rock and limestone, which is heated to over 2900 degrees F, extruded, and formed into slabs, cubes and blocks.

SECONDARY NUTRIENTS: Calcium (Ca) and magnesium (Mg) are considered to be the secondary nutrients.

SYSTEMIC: Used in reference to a disease within the plant tissue, not initiated from the external cells. Also refers to materials and compounds which are taken up or absorbed by the plant and designed to fight disease (e.g. systemic fungicide).


VERMICULITE: Mica which has been processed and expanded by heat. Vermiculite has excellent water-retention qualities and is a good soil amendment and medium for rooting cuttings.

WICK: Part of a passive hydroponic system using a wick suspended in the nutrient solution. The nutrients pass up the wick and are absorbed by the medium and roots.

ZINC (Zn): Like copper and manganese, zinc is linked to chlorophyll synthesis.

Lighting Glossary

AGROSUN: A metal halide bulb manufactured exclusively for Hydrofarm which puts out 38% more light in the red portion of the spectrum than regular metal halide lamps. Sodiums are also available with added blue.

AMPERE (AMP): The unit used to measure the strength of an electric current.

ARC: The luminous discharge of electricity between two electrodes in HID lighting.

ARC DISCHARGE: A transfer of electricity across two electrodes (anode and cathode), characterized by high electrode current densities and a low voltage drop at the electrode.

ARC TUBE: The enclosure which contains the luminous gases and also houses the arc.

BALLAST: An auxiliary piece of equipment designed to start and to properly control the flow of power to gas discharge light sources such as fluorescent and high intensity discharge lamps. In metal halide systems, it is composed of the transformer, capacitor and connecting wiring; sodium systems require an igniter in addition to the transformer and capacitor.

BU: An industry code indicating that the bulb is to be operated only in a base up position.

BULB: The glass outer envelope component of an HID lamp which protects the arc tube.

BULB WALL TEMPERATURE: The temperature at the bulb wall of a lamp, which effects lumen output and input wattage and which is important in lighting calculations.

CANDELA (CD): A unit of luminous intensity in a given direction, equal to one lumen per steradian.

CANDLEPOWER (CP): The luminous intensity of a light source, as expressed in candelas.

CANDLEPOWER DISTRIBUTION CURVE: A curve that represents the varying distribution of luminous intensity of a lamp or luminaire.

CAPACITOR: A n electronic device that can store electrical charge. The capacitor is one of the main components of an HID lighting ballast. Because they can store a very strong electrical charge, capacitors can be very dangerous to someone who is unaware of this fact and opens a ballast in order to examine or repair it. lf one does not know how to safely discharge the stored electricity, one should allow a trained technician to d o any ballast repairs.

COLD START TIME: The length of time required to bring an HID lamp to 90 % light output from a cold condition.

COLOR TEMPERATURE or KELVIN TEMPERATURE: The unit of measurement to express the color (spectrum) of light e miffed by a lamp; the absolute temperature of a blackbody radiator having a chromaticity equal to that of the light source (see correlated color temperature).

CONVERSION BULB: A bulb of a certain spectrum type (e.g. sodium) specially designed to operate while used in the fixture/ ballast of a different type (e.g. metal halide). The most popular conversion bulbs by far are sodium conversion bulbs, which allow one to have the sodium spectrum while still using a metal halide system.

CORRELATED COLOR TEMPERATURE (CCT): A specification of the color appearance of a light source, relating its color to that of a blackbody radiator, as measured in Kelvins (K). CCT is a general measure of a lamp's "coolness" or "warmness."

CANADIAN STANDARDS ASSOCIATION (CSA): Provides certification of consumer product testing, inspection, and advisory services for retailers and manufacturers. Accredited by the Occupational Safety and Health Association (OSHA), CSA can test and certify products to U.S, Canadian, and International standards for safety and/or performance according to UL, ANSI, I EC, etc.

DOME: The portion of an HID outer bulb located opposite base (the neck and threads).

DOME SUPPORT: The spring-like brackets which mount the arc tube within the outer envelope (bulb).

DISCHARGE LAMP: A lamp that produces light by discharging an electric arc through a mixture of gases and gaseous metals.

ELECTRODES: Filaments located at either end of a discharge lamp that maintain a n electrical arc between them. See arc discharge.

FIXTURE: The electrical fitting used to contain the electric components of a lighting system.

FLUORESCENT LAMP: A discharge lamp in which a phosphor coating transforms ultraviolet energy into visible light. Fluorescent lamps are good for starting seedlings and rooting cuttings, but do not have enough intensity to sustain aggressive growth in plants in the later stages of life, and are not efficient enough in their conversion of electrical power to lumens of light output.

FOOTCANDLE: A standard measurement of light intensity, representing the amount of illuminance on a surface one foot square on which there is a uniformly distributed flux of one lumen. More simply, one foot-candle of illuminance equal to the light emitted by one candle at a distance of one foot.

FREQUENCY: The number of waves or cycles of electromagnetic radiation per second, usually measured in Hertz (Hz).

HALOGEN LAMP: A short name for the tungsten- halogen lamp. Halogen lamps are high pressure incandescent lamps containing halogen gases such as iodine or bromine which allow the filaments to be operated at higher temperatures and higher efficiencies. While excellent for home lighting and similar applications, halogen lamps are not effective or efficient as grow lights due to their limited spectrum and high operating temperatures.

HID: The popular acronym for High Intensity Discharge.

HIGH-INTENSITY DISCHARGE (HID) LAMP: A general term for mercury, metal halide and high-pressure sodium lamps. HID lamps contain compact arc tubes which enclose various gases and metal salts operating at relatively high pressures and temperatures.

HIGH-PRESSURE SODIUM LAMP: High-pressure sodium lamps operate by igniting sodium, mercury and xenon gases within a sealed ceramic arc tube. Sodium lamps emit light energy in the yellow/red/orange regions of the spectrum; the red spectrum stimulates flowering and fruit production. Many indoor gardeners switch to sodium lamps when it is time to induce flowering o r fruiting of their plants.

HOOD: The reflective cover used in conjunction with an HID lamp. The more reflectivity a hood can provide, the more effective it is.

HOR: An industry code indicating that the bulb is to be operated in a horizontal position.

HOT SPOT: The area immediately under an HID lamp where the light intensity is strongest. Hot spots cause uneven growth, but can be remedied by using light movers.

HOT START TIME: The length of time required to bring an HID lamp to 90% light output after a short power interruption.

IGNITOR: A component of the ballast necessary for the starting of the bulb in sodium systems.

ILLUMINANCE: The density of incident luminous flux on a surface; illuminance is the standard metric for lighting levels, and is measured in lux (Ix) or foot candles (fc).

ILLUMINATION: The act of illuminating or state of being illuminated. This term is often used incorrectly in place of the term illuminance to denote the density of luminous flux on a surface.

INCANDESCENT LAMP: A lights source which generates light utilizing a filament wire (usually of tungsten) heated to white heat by an electric current passing through it. Incandescent lamps are the most familiar type of light source, with countless application in homes, stores and other commercial settings. Light is produced by passing electric current through a thin wire filament, usually a tungsten. Incandescent lamps are totally ineffective as grow lights; they have very limited spectrum are very inefficient in their conversion of electrical power to lumens of light output (lumen-to-watt ratio). They also put off far too much heat per watt to use in horticulture, even if the abovementioned problems did not exist.

INTENSITY: A term referring to the magnitude of light energy per unit; light intensity diminishes evenly as you get further from the source.

KELVIN TEMPERATURE (K): The unit of measurement to express the color (spectrum) of light emitted by a lamp; the absolute temperature of a blackbody radiator having a chromaticity equal to that of the light source (see correlated color temperature). A standard clear metal halide HID lamp has a n average Kelvin temperature rating of 4,000 K.

KILOWATT (kW): A unit of electric power usage equals 1,000 watts.

KILOWATT HOUR (kWh): A measurement of electric energy usage. A kilowatt hour is equal to 1,000 watts of power used over a period of one hour.

LAMP: A n electrically energized source of light, commonly called a bulb or tube.

LAMP LIFE: A measure of lamp performance, as measured in median hours of burning time under ANSI test conditions.

LAMP LUMEN DEPRECIATION (LLD): The decrease over ti me of lamp lumen output, caused by bulb wall blackening, phosphor exhaustion, filament depreciation, and other factors.

LAMP STARTING: Generic term used to describe a discharge lamp's starting characteristics in terms of time to come to full output, flicker, etc.

LIGHT: Radiant energy which can be sensed or seen by the human eye. The term generally applied to the visible energy from a source. Light is usually measured in lumens or candlepower. When light strikes a surface, it is either absorbed, reflected or transmuted. Visible light is measured in lumens.

LIGHT MOVER (e.g. Hydrofarm's Light Track): A motorized device which moves an HID lamp back and forth across the ceiling of a grow room to provide more even distribution of the light.

LUMEN: A measurement of light output; refers to the amount of light emitted by one candle that falls on one square foot of surface located at a distance of one foot from the candle.

LUMINAIRE: A complete lighting unit, consisting of a lamp or lamps together with the components required to distribute the light, position the lamps, and connect the lamps to a power supply. Often referred to a s a "fixture;"

LUX: A standard unit of illuminance. One lux is equal to one lumen per square meter.

METAL HALIDE LAMP: A high-intensity-discharge lamp in which the light is produced by arcing electricity through a mixture of metal halides. The light produced by metal halide lamps is in the white-blue spectrum, which encourages vegetative growth and "bushiness" while discouraging upward growth. This is the bulb to use in the first, vegetative phase of plant growth.

MERCURY VAPOR LAMPS: The oldest member of the HID family, mercury vapor lamps work by arcing electricity through mercury vapor. While more efficient than incandescent, halogen and fluorescent lamps, mercury vapor lamps have the least efficient lumen-to-watt ratio of the entire HID family. This, combined with an improper color spectrum for horticultural applications, makes mercury vapor lamps a poor choice for a grow light.

NECK: The narrow, tubular end of the HID bulb, attached to the threads.

PARABOLIC REFLECTOR: Alighting distribution control device that is designed to redirect the light from a n HID lamp in a specific direction. In most applications, the parabolic device directs light down and away from the direct glare zone.

PHOTOPERIOD: The relative periods of light and dark periods within a 24-period. Also referred to as day length.

PHOTOSYNTHESIS: The growth process by which plants build chemical compounds (carbohydrates) from light energy, water and C02 (carbon dioxide).

PHOTOTROPISM: The gravitation of a plant part toward a light source.

REFLECTOR: The term sometimes used to refer to the reflective hood of an HID lamp.

REFLECTIVITY: The measure of the reflective quality of a surface; the relative ability of a given surface to reflect light away from it without absorbing, diffusing or otherwise compromising the light's quality, intensity and spectrum.

SOCKET: The threaded, wired receptacle that an HID bulb screws into.

SODIUM LAMP (HIGH-PRESSURE SODIUM LAMP): High pressure sodium lamps operate by igniting sodium, mercury and xenon gases within a sealed ceramic arc tube. Sodium lamps emit light energy in the yellow/red/orange regions of the spectrum; the red spectrum stimulates flowering and fruit production. Many indoor gardeners switch to sodium lamps when it is time to induce flowering or fruiting of their plants.

SON-AGR0: A sodium bulb which, according to the manufacturer, produces 30% more blue light than standard sodium bulbs. The 430-watt SONAGRO also emits 6% more light than the standard 400-watt sodium lamp.

SPECULAR REFLECTION: The redirection of incident light without diffusion at an angle that is equal to and in the same plane as the angle of incidence. The specular inserts included in Hydrofarm's HID lighting systems work on this principle.

STERADIAN: A unit solid angle on the surface of a sphere equal to the square of the sphere's radius.

TRANSFORMER: The component in the ballast that transforms electric current from one voltage to another.

U (for UNIVERSAL): An industry code indicating that the bulb can be operated in any position: horizontal, vertical (base up) or any other.

ULTRAVIOLET (UV) LIGHT: Light with very short wavelengths, out of the visible spectrum.

UNDERWRITERS LABORATORIES (UL): A private organization which tests and lists electrical (and other) equipment for electrical and fire safety according to recognized U L and other standards. A UL listing is not an indication of overall performance.

WATT (W): A unit used to measure electric power. One watt equals one joule/second.