Indoor Lighting
I can't explain on a webpage what goes into lighting and the indoor environment. In all cases, I suggest you ask a Hydroponic Store for Advice, but I can give you a few guidelines as to what to expect.
Spectrum:
Spectrum is the colours that the plants use. Plants use Oranges to Reds more than any other colour. They give the plant the highest energy levels. But without enough Blues they will become unhealthy and spindly. Blues cause a plant to grow bushy and leafy, but reds encourage the upward growth. Ultra Violet doesn't help much, in fact outdoor growers have seen improvements in plant growth when grown under a sheet of UV protectant glass. Infra Red Light is Heat, and doesn't help unless heat is required.
Light Intensity:
Light Intensity is important as well as colour spectrum. You can't stare at the sun without damaging your eyes, so you can imagine the brightness that plants require to grow to maturity. The more the total leaf area, the greater the light required to keep the plant healthy. Therefore, the low light intensity of fluorescents work best for cuttings, and seedlings, or for supplemental light, where indoor type plants are not getting enough sunlight.
Fluorescent:
Fluorescent tubes have been used for seedlings, tissue culture and cuttings for a great number of years. The most commonly used is GROLUX and Activa 172 tubes, but also Powertwists and other speciality Fluroscents, as well as Cool White tubes (as used in plant terrariums e.g. Phototron). By using Fluorescent tubes, to achieve mature growth, plants must be grown as close to the tube as possible, without touching the tube, as this may cause burning of plant tissues. The closeness of the tubes is required as each tube only outputs the minimum light required for plant growth (about 1000 foot-candles) and if further away from the tube, the output of the light diminishes. Always use a horticultural reflector. Because a fluorescent tube is round, light is travelling in all directions from the tube, and any light travelling upward, or sideways will miss the plants below. Reflectors redirect this light in a favourable manner and generally increase the light to the plants by 50% to 95% with any standard lamp..
The benefits of Fluorescents are smaller internodal lengths, smaller leaves and smaller flowers but more numerous. Plant growth may be slower than expected.
Incandescent:
The filament design of household incandescent lights reduce the average life span of each bulb well below that of Fluorescent. Incandescent output too much of their light in the red band of the spectrum making these unsuitable for plant growth. Colour corrected bulbs are available such as CROMPTON, and these output around 5000 foot-candles, and are suitable for plant growth, however they are more suitable for supplemental lighting, where plants already receive some light from the sun, e.g. most indoor plants, and seeds and cuttings can benefit from the small amount of heat they produce. Incandescents are frequently used to confuse a plant in greenhouses and tunnel-houses by extending the day length. The plants are exposed to a longer day than usual, and when this additional day length is removed, flowering and fruiting plants can be induced to produce their fruit or flowers out of season.
Contact a store or your Department of Agriculture/Primary Industries for more information.
HIGH INTENSITY DISCHARGE LAMPS
Metal Halide:
Metal Halides are available in 400 Watt (60,000 foot-candles) and 1000 Watt (100,000 foot-candles), and sometimes in other sizes. They emit a blue/white light and are used for increasing plant growth rates, controlling the seasons (Photoperiodic control) and for indoor growth, away from pests, disease, wind, rain, heat or cold extremes, as well as the healthy growth characterised by these plants. Hobbyists use these lights for these reasons and for limited growing areas where indoor gardens may be either more viable or decorative. Metal Halides are very suitable for healthy vegetative growth, flower growth and produce excellent large, bushy plants. These lamps require Metal Halide control equipment, which is sort of like a transformer and starter put together.
High Pressure Sodium:
High Pressure Sodium’s are available in 400 Watt and 1000 Watt sizes, as well as other sizes. They emit a spectrum of red/orange/yellow and have been compared to the autumn or harvest sun. There has been in the past, considerable debate over whether Halides or Sodium’s are more suitable for plant growth. The High Pressure Sodium lights are best known for their longer life, higher light output and flowering capabilities, but with less blue light than Halides, some plants may not produce the healthy vegetative growth when used alone. High Pressure Sodium are ideally used in conjunction with Metal Halides to produce a brilliant plant growth environment, and an excellent spectrum full of high energy reds, and blues that keep the plant compact and healthy. Sometimes Halides are used up to the flowering stage and High Pressure Sodium is used from this point for increasing the flower/fruit size and weight. Son T Agro Lamps (see below) are an example of a lamp designed to incorporate these two spectrums. High Pressure Sodium’s require High Pressure Sodium Control Gear.
Because of the requirement for different Halide and high-pressure Sodium control gear (also known as ballast) the retrofit bulb was created.
Retrofit Bulbs:
There are High Pressure Sodium retrofit bulbs available for running in Metal Halide ballasts. They are available in a 350-Watt and 360-Watt lamp sizes for running in 400watt Metal Halide ballast’s. High Pressure Sodium retrofit bulbs do not have the longer life and higher light intensity of Standard High Pressure Sodium’s, but Metal Halide systems are cheaper and run at a slightly lower amperage than High Pressure Sodium ballast’s. Ideally, both a High Pressure Sodium and a Metal Halide should be used throughout the flowering cycle, however, Retrofits provide an economical alternative for the hobbyist when a distinct lighting source is required for flowering as opposed to another light source for flowering.
Son T Agro Bulbs:
Son T Agro Bulbs are a new development from Phillips. They run in 400 Watt High Pressure Sodium Control Gear, and they are basically a modified High Pressure Sodium Lamp with 30% more Blue light in it's spectrum, making it the best lighting system for plant growth, with high energy reds to speed growth, and enough blue light to keep plants compact and healthy. With No Lamp change required when plants begin to flower, Son Agros are now the most popular growing system on the market. Son Agro Lighting sources are only 400 Watt, but are brighter than 400-Watt Metal Halides. PL90E fittings are used in Holland extensively, with Son T Agro Lamps. Holland’s use of Son T Agros represent the largest usage of lighting for commercial purposes in the world. (Consider growing plants in winter there. Sometimes the 4 hours they call daylight is not overcast, but not often. Without lighting, growing vegetables or flowers is quite difficult.)
Used in the European PL 90 E Fixtures the coverage of the light is more than that of a 1000-Watt Metal Halide lamp in a normal Australian fitting. Mathematics tells you that Son T Agros at 400 Watts use only 40% of the power of the 1000-watt!
Planta -T Lamps:
To produce a lamp that matches the plant sensitivity curve, the Son T Agro was not quite high enough in the blue spectrum. This Osram Lamp is designed to match the plants requirements for an ideal light source, without reducing efficiency per watt. They are as bright as Son Agros, and High Pressure Sodium’s, but have more blue. Results under these lamps are excellent leaf production as well as good flower production.
Ensure you have a good High Pressure Sodium Ballast, that is a high performance ballast. (Short or Long Stage Ignitors will not ignite a Planta T.) High Performance ballast’s, incidentally, will ignite lamps that will no longer ignite in normal ballast’s.
Running costs:
The running cost of anything running at 400 Watts is around 4 cents for every hour running (assuming a Kilowatt-hour is 10-11cents). If you examine your fan heater (usually 2400watts), Hairdryer (1200Watts), Air-conditioning (1500Watts), Pool Pumps (up to 1500watts) and other appliance wattages, you may be very surprised! With lighting, if a 12 hour day is used this is roughly three dollars a week. High Intensity discharge lights are therefore regarded to be more efficient (light intensity vs. wattage) than Fluorescent. (Considering Fluorescents are advertised for their energy efficiency) For a 1000-Watt light the costs are around 11 cents per lamp. (Figures based upon 11cents per kilowatt-hour)
Greenhouse / Growroom sizes:
I'd recommend placing lights two to three feet above the plants for optimum growth rates . At this height, a minimum of one 400 Watt per 1.5m x 1.5m or a minimum of one 1000 Watt per 2.5m x 2.5m to maintain the optimum growth rate. If a light is raised the growth rates slows. At four feet above the plants you should maintain a reasonable but slower growth rate, and the useful area should about double. When attempting to stretch the light source, it is difficult to say what the average would be as reflector type and plant types can affect the outcome. Use of a light meter would help your growroom design.
I have used a PL90 E to light areas up to 3 meters by 2 Meters effectively with the running cost of only 400-Watts.
Lighting Accessories:
Light Rails move lights over the plants slowly to improve growth. These cost around the price of a lamp, but are very effective in making plants bushy, without growing straight up toward the light source. Reflective plastic (white and Black) is excellent for doing the same thing. You hang this plastic like a curtain to reflect the light back into the plant growth. NEVER use aluminium foil, or insulation foils, as these are designed to reflect heat, not light. These foils tend to affect the spectrum, and reflect less visible light, and keep your growroom too hot. Some mirror films and Mylar are okay, but only purchase it as is recommended by a Hydroponic Store.
Ventilation:
Ventilation is the key to a good growroom. If you do not have enough fresh air, and a suitable temperature, plants can suffocate. An exhaust fan, especially the steel ball bearing types are quiet and much more efficient than 10 of the budget ceiling fans. Ideally you should have a fan with an air exchange of 10 to 15 times the growroom size per hour. Remember, the more fresh air the better. Carbon Dioxide Enrichment systems are fine when a grower is experienced, but to a beginner they represent more problems than they are worth. Ask a Store for advice.
The results of using lighting in an indoor environment are at least remarkable.
The benefits of controlling a plants environment are numerous, and you should speak to your local Hydroponic Store about the results obtainable.
NOTE FOR THOSE "ACQUIRING" LIGHTS FROM OTHER SOURCES THAN THOSE OF HYDROPONIC STORES..... The above is a GUIDE ONLY! When considering a Lighting System for plant growth it is important to ensure every consideration is taken into account, for example reflectors, burning position of bulbs, ballast’s etc. Many systems designed for lighting large areas have NO PLACE IN HORTICULTURE! They can BURN the leaves, reflectors may destroy the spectrum and cause unhealthy growth. If you come across other systems, describe them to a Hydroponic Store who will tell you if the system is suitable, or can be modified! PLEASE SPEAK TO THE EXPERTS FIRST!
Controlling stages of growth under artificial lighting.
This should only be used as a general guide. Ask your store if they have anything further to add. For the following, I have assumed that no sunlight will be used to supplement growth.
1. Seeds and Seedlings.
All a seed needs to germinate is warmth and moisture. A seed has all the nutrients it needs in the husk of the seed. Generally, the medium used to germinate a seed must be well draining, but remain moist to the touch. Although moisture levels may vary for different varieties, the medium must not be too wet. The media is best described as not dry and never very wet. ( Other descriptions of moisture levels could be described as like a sponge used to wipe a counter. Not so wet as to leave water on the counter, but not so dry that it does not clean.)
Once a seed has sprouted it is a good idea to give it some indirect light in preparation for its first leaves. ( Lighting should be Fluorescent close to the tops of the seedling or a Metal Halide / Son Agro about 1 meter from the seedlings ) The Seedling will sprout with small "false" leaves (cotyledons or seed leaves), but when the first true leaves appear it is a good indication that the seedling now has roots and you should apply nutrient from now on. For the first week, half strength nutrient can be applied. It should be noted that the first two weeks of life are critical. If a plant does not have a good start, then you can say generally that the plant will not grow to be an excellent plant.
2. The Vegetative Cycle.
Once a seedling becomes a young plant, full strength nutrient should be used (On average 2 to 4 sets of true leaves is a young plant). Using a CF meter, adjust your nutrient to the correct strength for your crop. If you do not own a meter yet, mix nutrients according to pack directions. Your store should be able to provide you with specific crop directions. Metal Halide Lighting is the best light source to use at this point. Lamps should be 2 to 3 Feet from the tops of the plants. The Photoperiod or length of artificial daylight is best set at 18 Hours with a normal household timer. Other "day" lengths are discussed below. The rate of growth will gradually become faster; Young plants usually grow slower than they do when they become maturer. A Vegetable or flower that has been grown at 18 hours per day of HID lighting can be induced to flower/fruit as early as five weeks (approx) but better end results occur when the plants are eight weeks old or more before reducing the light hours. The plants are growing at such a rate that they give better results if their metabolic age and chronological ages have a chance to catch up on each other. It is during the vegetative stage that growers should take their cuttings or clones. For more detailed information on cloning, please consult our staff.
3. The Reproductive Cycle.
The Light hours can be reduced to induce Flowering or Fruiting. Once the light hours are reduced to 12 Hours, ensure that the plants receive NO LIGHT at all during their dark 12 Hour "night". Should you open a door to your growroom and allow light from a hallway light to enter the room during their 12 hour sleep, this will stress the plants by "waking" the plants up and putting them back to "sleep". Stress is to be avoided at all stages of growth. This stress will slow the flowering process. Plants require less nitrogen during this cycle, and will consume more Phosphorus. There are two ways to combat this. Either increase the strength of your starter nutrient with a CF meter, or purchase one of the range of Bloom solutions/additives available. No one really understands why the red spectrum of light stimulates and increases the floral hormones of a plant, but the effect of an autumn sun is more in the red band of the light spectrum. What we do know is that during flowering, a High Pressure Sodium Lamp will add to your total flowers/fruit if used with a Metal Halide during this Cycle. Many Growers will run High Pressure Sodium during flowering alone, and this can still increase the crop significantly. It could be noted however; Metal Halides will be enough during the flowering and fruiting stage to produce good results. It is worthwhile to have High Pressure Sodium for the results are usually larger flowers and/or fruit and more numerous flowers/fruit, as well as significantly shorter flowering time. Son Agros are suitable during both growth and flowering stages.
Flowers generally will be visible in one to four weeks. (If not, it is likely that the plants were stressed by poor ventilation, heat, cold, produced from poor cuttings or seedlings, were an offspring of a sickly variety of that plant type or were too young to be "flowered".) From then it is only a matter of time for your plant to produce ripe fruit or fully form their flowers. Plants can be harvested and an 18 Hour Vegetative Cycle begun again. Whether your plant is better off started from seed, cutting, clone or re-cropped at this point cannot be generalised. Ask your store for advice.
Other Options.
A plant requires a minimum of 8 Hours lighting out of every 24 hours. But the light hours must be long enough to enable you to reduce them and create an artificial autumn. If 18 Hours is used, then a reduction to 12 hours will induce flowering and fruiting in most plants. This is done in order to induce flowering and/or fruiting with most plants where required. Obviously, you are not interested in flowering or fruiting Lettuce, because you are more interested in the leaves. With Chrysanthemums, or fruiting crops, you will require a shorter day length to induce the plant into its reproductive cycle. If you use 12 Hours for your initial cycle, then reduction to 8 Hours will result in Flowering. However, that the plants would take longer to grow to a point where flowering could take place, and flowering may take longer to come on. Should you have any problems, please do not hesitate to contact your local Hydroponic Store. It is through talking with them that they can help you get the most out of your garden. Besides, the advice is free.
TIPS.
1. When assembling your light for the first time, screw the bulb in until it is finger tight, and then give it a little more of a twist to ensure a firm contact. After a week to two weeks, the contacts will have worn in, and could need a little more of a turn.
2. Many people use nylon rope to hang their lights. Ensure they do not contact the bulb and melt. I would recommend welded link chain. Unfortunately, these do not go through pulleys very well, but it can be easier to unhook the light and move it up a couple of links at a time.
3. Make sure your plants are well ventilated. A plant is 90% water and carbon. The only way a plant can take in Carbon is through the Carbon Dioxide in the air. If the Carbon Dioxide content in the garden is not replenished, plants will grow more slowly and could develop problems.
4. The optimum temperature of the growroom is between 22 and 25C and the optimum Humidity levels lie between 40% and 60% Relative Humidity. Generally, it may be difficult to obtain this range of temperature and humidity, however as a general rule, try to keep the room as close to the optimums and most plants will adapt themselves to their environment. Try to avoid sudden leaps of humidity or temperature as this may shock your plants. If you maintain the environment within the optimum ranges, you will see a much better growth rate.
5. Remember that Light is one of the most essential ingredients in plant growth. If poor growth occurs in any environment, 90% of problems relate to LIGHT, OXYGEN IN THE ROOT ZONE, pH (Acidity/Alkalinity), NUTRIENT STRENGTH, TEMPERATURE AND VENTILATION. Think about these factors as discussed at the start of this book.
Guidelines for the Media used in Hydroponics.
Media should be disease free.
Media should not have any nutrient quality of its own, or the whole point of a balanced nutrient solution is lost. If the Media adds Calcium for example, how much, and does it change, and is it soluble? It's best if we determine the nutritional balances for the plant not the media.
Media must be pH stable, and reasonably inert.
Media should be high in oxygen.
Media should not have overheating problems, such as gravel does in the Northern Queensland sun.
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