Hydroponic Lighting RequirementHydroponic Lighting GuideHydroponic Lighting ScheduleHydroponic Lighting Timers Hydroponic Lighting requirement:Hydroponics is the method by which plants are grown without soil, using mineral nutrients dissolved in a water solvent. We all studied in our science books that plants need sunlight as a catalyst for photosynthesis, the process through which plants make their food or grow. Same is the case with the hydroponically grown plants. During photosynthesis, plants trap light energy with their leaves and use this energy to change water and carbon dioxide into oxygen.and a sugar called glucose There are three dimensions of light that are important for optimal plant growth.These are Lighting spectrum, Light intensity and Light duration. Each of them has an impact on plant growth. Plants may need different color spectrum based on their type and growth stages. Some may need higher intensity and some may need lower intensity light. Some may need light for longer duration and some for shorter durations. Following is a brief overview of all the three dimensions of light that plants might need.As for spectrum dimension, we know that white light from the sun consists of 7 different colors which are called spectrum of the white light. The intensity of these colors depends upon the wavelength of light as we know Red colour has the longest wavelength and Violet has the smallest. Now, some of those colors can be beneficial for a certain kind of plants and some other colors can be beneficial to another kind of plants. Some colors can be beneficial to a certain plant at a certain life stage and some other colors at a different life stage. If the plant is in growth stage, it will be needing Blue side of the spectrum while if it is in the fruiting or flowering phase, Red end of the spectrum will be beneficial for it.To understand light duration, we know that in addition to photosynthesis in the day, plants respire (Use oxygen to metabolise glucose and give Carbon dioxide as a waste product) in the night. So darkness is also an important part of plant’s life cycle. This darkness period may vary from plant to plant. Based on the light requirement,plants can be divided into Long day,short day and day neutral plants. Also, same plants may need different light durations based on their growth stages.Light intensity refers to the strength of the light. Intensity is also an important factor in plant growth. If the plant consists of flower and fruit e.g  Vegetables ,it will be needing intense light. If the plant consists of foliage like leafy green, salad or seedling, it will be needing less intense light.Like all other plants, sunlight is the best source of light for plants for hydroponically grown plants. It is natural light which best meets the plant requirements of intensity, spectrum and duration. What if sunlight is not available? Thanks to technology, there are alternatives available to sunlight. These alternatives include a range of different types of man made lights known as grow lights or plant lights. Their spectrum may resemble spectrum of sunlight or a part of spectrum of sunlight. With the help of these lights or with a combination of these lights, you can grow plants indoors where light is not available, in the winters when sufficient light is not available in day hours and according to custom needs of your plant. Hydroponic Lighting Guide:Factors to consider while choosing a Grow LightIt can be a difficult task for a beginner to choose the best lights for their hydroponic system but the following hydroponic lighting guide will make it easy for you.There are different types of grow lights available in the market. Each has its strong and weak points. So the choice rests with the user depending on the following two factors:  1).The needs of the plants they grow. To understand when a certain type of grow light is to be chosen based on the Intensity and dominant part of the spectrum it produces, you will need to consider the type of the plant and the growth stage of the plant you are growing. If the plant consists of flower and fruit,it will be needing intense light. If the plant is leafy green,salad or seedling, it will be needing less intense light. If the plant is in growth stage, it will be needing Blue side of the spectrum while if it is in the fruiting or flowering phase, Red end of the spectrum will be beneficial for it.2). Priorities of the user (economy, efficiency etc) like in terms of power consumed(wattage) vis a vis intensity of light produced and in terms of cost benefit analysis, meaning how much cost the user can bear based on the cost of the plants he produces.Following is a brief overview of popular grow lights with their strong and weak points based upon the above factors to help the user choose the best type of light suited for the plants they are growing. HID LightsHID(High Intensity Discharge) lights are the most popular grow lights for now, mostly used by professionals. They are highly intense and provide a very high quantity of visible light per watt of electricity consumed meaning they are highly efficient. They are classified into different types based on the material used to make them and the type of light they produce. Their types include Metal halide(MH), High pressure sodium(HPS), Conversion bulbs and Mercury vapor, of which, High pressure sodium(HPS) and Metal halide(MH) are most commonly used as they produce a color spectrum that is similar to that of the sun. Excessive heat production is a drawback of these lights. They are screwed into a hood looking fixture so that they can reflect light onto the plant. HID lights require a ballast to operate. Each ballast has a particular wattage. Popular ballasts are of 150W, 250W, 400W, 600W and 1000W with 600W being most electrically efficient. HPS LightsHigh-pressure sodium bulbs deliver more energy in the Yellow/Red part of the light spectrum which is why they help promote blooming and fruiting(at later stages of plant life). They can be used as a standalone source of light indoors or in supplement to natural daylight in greenhouse lighting and to full-spectrum lighting(metal halide). If used alone, some drawbacks may include elongation of plants due to lack of blue/ultraviolet radiation, and difficulty in monitoring of plants due to yellow light. These problems can however be resolved by supplementing them with source of blue light like Metal Halide(MH) or by better adjusted spectrum of HPS light and by use of supplementary lights to offset the yellow light respectively. High-pressure sodium lights are a more efficient type of HID lighting than metal halides. They also last twice as long as Metal halide bulbs which need to be replaced about once a year. HPS lights are the industry standard for most indoor growers. Metal Halide lightsMetal halide bulbs are a type of HID light that emit light which is similar to the light that is available outdoors during spring because they focus on the blue and violet parts of the light spectrum. They are well-suited to supporting plants in earlier developmental stages by promoting stronger roots, better resistance against disease and more compact growth. The blue spectrum of light encourages compact, leafy growth and is better suited to growing vegetative plants with lots of foliage. They are commonly used when the plants are on display in the home (for example with ornamental plants) and natural color is preferred because plants look more pleasing under a metal halide than other types of HID lights such as the High-pressure sodium bulbs which distort the color of plants. There are color corrected MH bulbs available which give off more red/orange light than regular metal halides. This helps boost flowering in addition to supporting compact foliar growth.Their life span is around one year.LED Grow LightsLED(Light Emitting Diodes) grow lights are often used for supplemental lighting in home and office spaces but can also be used alone. They provide plants a balanced spectrum of red, blue and green. Green, Red, far-Red and Blue light spectra have an effect on root formation, plant growth, and flowering. Output waveband of single color LEDs is much narrower than that of traditional sources of lighting used for plant growth. LED grow lights are available in different colors depending on the intended use but there are not enough scientific studies or field-tested trials using LED grow lights to recommended specific color ratios for optimal plant growth under colored LED grow lights. They produce less heat than many alternative lighting systems and have a built in cooling system. They have a long lifespan extending up to 5 years. They are popular especially with hobbyist growers that are looking to minimize their long term costs without sacrificing a lot of value. In the past, they were expensive and users were disappointed with their performance but with improving technology, cost reduction, better adjusted spectrum and option to select specific wavelengths for a targeted plant response, they are becoming a more viable option for the growers. LEDs do not require a ballast to operate. They may cost more at the time of buying but they prove cost efficient in the long run.Fluorescent Grow Lights Fluorescents are also widely used as grow lights.They are not as intense as HID lights and are usually used for growing vegetables,herbs,vegetative-only plants like microgreens or salad greens or for starting seedlings to get a jump start on spring plantings. Fluorescent lights come in many form factors, including long, thin bulbs as well as smaller spiral shaped bulbs (compact fluorescent lights). The two main types of fluorescent lights used for growing plants are the tube-style lights and compact fluorescent lights.Tube Style Fluorescent Lights Tube style fluorescent lightings are low intensity lights. Due to their less intense light, they are not very well suited for flowering and fruiting stages of plants. They are good for leafy greens, seedlings and cloning as they do not have to go through flowering stage and need less intense light. They are available in many types including the T5, T8 and T12. T5 is the brightest and most popular version among them. The T8 and T12 are less intense and are used with plants with lower light needs. T5 is available in different sizes. High-output fluorescent lights produce twice as much light as standard fluorescent lights. They provide high intensity light and are an improvement in the fluorescent light. A high-output fluorescent fixture is thin and occupies less space, making it useful in areas where space is vertically limited. T5 high output fluorescents can produce light up to 5000 lumens per tube. They produce very little heat which is why they can be placed close to the plant. Fluorescents have an average usable life span of up to 2 years. A ballast is needed to run these types of fluorescent lights.CFL Grow Lights Compact Fluorescent lights (CFLs) are smaller versions of fluorescent lights.They are useful for propagation and situations where relatively low light levels are needed although their light intensity is greater than tube type fluorescent lights. While standard CFLs in small sizes can be used to grow plants, there are also now CFL lamps made specifically for growing plants. Often these larger compact fluorescent bulbs are sold with specially designed reflectors that direct light to plants, much like HID lights. Compact fluorescent bulbs are available in warm/red , full spectrum or daylight and cool/blue versions. Warm red spectrum is recommended for flowering, and cool blue spectrum is recommended for vegetative growth. They’re cheap, easy to use, can cover a lot of space and are used by hobbyist growers and people who want to save on money. CFLs do not need a separate ballast to run which further reduces their cost. Usable life span for compact fluorescent grow lights is about about a year.Plasma Grow Lights Plasma grow lights generate light by exciting sulfur plasma with microwave radiation. They provide complete spectrum of light that is good for vegetative growth.The color produced by these lights looks beautiful, almost like sunlight. Light emitted by them penetrates further than most  LEDs, and CFL lights but less than HID lights. Intensity of the light emitted by sulfur plasma lights last much longer than metal halide or high pressure sodium lights. As they lack electrodes, they have a longer lifespan reaching upto 4 years. They use 50% as much energy as HID lamps.On the downside, they are much more expensive than most other types of lighting, even higher-end LEDs. The bulb emits a lot of heat and will require a fan for cooling. This technology is new and relatively untested by third parties and we have to rely on most information by the manufacturer.  Wattage :20 to 40 watts are needed per square feet depending on the plant requirement and the source of light being used. For high-light plants like tomatoes you will want to achieve around 40 watts per square foot for optimal growth and fruit production. For low light plants, and small leafy plants like herbs and lettuce, you will only need to achieve about 25 to 30 watts per square foot. Then, according to the light source, LEDs need almost 30 watts to cover a square foot,HIDs need almost 40 watt to cover a square foot while fluorescent lights might need 50 watt per square foot.To determine the wattage, first step is to find out the square footage of the area you are trying to light.Then multiply the square footage to the wattage need of your light used i.e 30 for LED,40 for HID,50 for CFL and you will have your desired total wattage you need.   Energy consumption: An LED grow light bulb produces 100 or above lumens/watt, an HPS bulb 60-140 lumens/watt, a metal halide bulb 60-125 lumens/watt, a fluorescent tube grow light 33-100 lumens/watt, a CFL 44-80 lumens/watt, depending on the wattage of the bulb. In order of energy consumption from low to high, Sulfur Plasma lights come first, then the LED lights, then HIDs and then the CFLs. LEDs are efficient than HIDs and the need less or no ventilation and air conditioning depending on the size of the setup and ambient temperatures. Sulfur Plasma lights use 50% as much energy as HID lamps.The energy saving that growers can expect from using LED grow lights instead of HID is around 35%. Similarly, HID lights are twice as efficient as fluorescent lamps; one 400-watt HID lamp emits as much light as 800 watts of fluorescent tubing.     Best grow lights for some common plants in hydroponic system:As we have discussed before, there is no hard and fast rule about selection of light to grow plants in hydroponic system. Many types of lights can perform the desired function but their performance may vary. Various factors come into play while choosing the best light for the plants grown by a user including economy, efficiency, cost benefit analysis of the user and most importantly, the requirement of the plants.On the basis of requirement of the plants, following types of lights are good for common hydroponically grown plants.Plants like tomatoes,cucumbers, Peppers,cabbage need to undergo flowering and fruiting stages. You can use fluorescent lights for their seedling stage as they do not need high intensity light at this stage. Then, you can use metal Halide for growth of the plant and use High Pressure Sodium for the development of fruits. Spinach, Basil, Coriander, watercress and Lettuce are leafy green plants. They do not need much heat and need less intensity of light to grow. Fluorescent lights are a good option for growing these plants indoors.For strawberries, Blueberries and cannabis, LED grow lights are a good choice.      Hydroponic lighting schedule:There are three reasons to set up a lighting schedule for your hydroponic plants. First is less electricity costs due to efficient usage of light. We know that High Intensity Discharge lamps, including metal halide or high pressure sodium that are the best to be used for hydroponic systems, use too much electricity. So,by setting up a schedule for optimizing hydroponic lighting,electricity cost can be reduced.Secondly, revisiting our science book, we know that plants respire (Use oxygen to metabolise glucose and give Carbon dioxide as a waste product) in the night. So darkness is also an important part of plant’s life cycle. Just as plants grown outside have a period of darkness in the night, plants grown inside a room or greenhouse need periods of darkness to grow smoothly. This darkness period may vary from plant to plant. To provide this darkness period which is a necessary requirement to the plants,you need to develop a lighting schedule. Based on plant requirement of period of light, we can divide plants in three types of plant categories namely long day plants, day neutral plants and short day plants. Long Day Plants: They require long periods of sunlight, upto 16-18 hours per day. They include wheat, lettuce, potatoes, spinach, wheat, turnips and bromeliads. The long-day cycle is similar to the natural environment of summer-flowering plants and also includes the plants which grow in this period. Day Neutral Plants: They are the most flexible in terms of light and darkness timing. They tend to bear fruit no matter how much light they are exposed to. The optimal light and dark timing for this kind of plants is 14-18 hours of light and then switching your system off for up to 6-10 hours. They include rice, eggplant, roses, corn, zinnias, tomatoes and strawberries, as well as many other similar fruits and vegetables.Short day plants: They require a long period of darkness and short period of light to photosynthesize and produce flowers. If they are exposed to over 12 hours of light per day they will not flower. Optimal hydroponic light timing schedule for this type of plants is 12 hours and off for the other 12. They include Poinsettias, strawberries, cauliflower and chrysanthemums. The short-day cycle is similar to the environment for plants that flower in the spring. Problem arises when you have to grow long day plants together. The best solution is to isolate them in your greenhouse.But if that is not possible,you will have to adjust your lighting schedule to a compromise between the two as it would not be possible to offer both of them the perfect conditions. You need 16-18 hours of light for long day plants like lettuce and 12 hours for short day plants like strawberries. You can reach a compromise for your hydroponics system at around 14 hours so that the difference is offset and both types of plants can get best composition of light possible. Thirdly, same plants may need different light durations based on their growth stages. Generally speaking, during the seedling/clone phase, plants should receive 16 hours of light and 8 hours of darkness. The vegetative phase typically requires 18 hours of light and 6 hours of darkness. During the final, flower stage of growth, plants may need 12 hours of light and 12 hours of darkness. Hydroponic light timers By far you know that plants need both light and dark periods and have different lighting needs. So,You need to set a schedule for them to receive light according to their needs. You can do it either manually or automatically. Doing so manually will take a lot of time and effort and may not be physically possible. So it is better to do it automatically. Using a timer,you will be able to give your plants specific light/dark cycles to help them to thrive.Timers are easy tools which help you to set periods of light and dark and turn the lights off and on automatically. These are typically low-cost and simple electronic appliances that you hook into a socket and put the plug for the hydroponic lights into the front of the unit.Following  are a few steps for you to effectively use the hydroponic timer.First, you have to set a plan of light cycles according to requirement of your plant. You may want to have cycle of 12 hours light and 12 hours dark or you may want to have 18 hours of light with six hours of darkness. Answering these questions will help you choose the range of timer you need to use.Secondly, buy a timer according to your light cycle need.Then you need to plug your timer into the socket and plug the grow light plug into the timer. Set the timer according to the light cycles you have determined for your plants according to their requirements. It is better to choose a timer that is grounded(3 prong plug). Grounding helps to prevent certain types of electrical shocks. Timer readouts may be analog or digital. It is upto you to choose if you need an analog or a digital readout for a hydroponic timer. Timers can be either manual or electric. Manual timers use pins and have two plugs on either side so that you can attach it to two lamps at once. Manual timers are less likely to break than electric.