Lighting

There are a lot of considerations that go into a first room. Everyone wants to grow thousands of pounds of the lushest tomatoes ever, with basil as tall as your shoulder, but this is massively unrealistic. Four plants that bear fruit are a great start. Each setup can be halved or doubled as needed.

The main portion of the light used by plants is referred to as the PAR zone: Photosynthetically Active Radiation. The higher the PAR, the more usable light is available to your plants. Unfortunately, not all bulb makers designate a PAR rating.

Another, often more available, rating is the foot candles or lumens. Both of these terms are used interchangeably for the grower. Lux is a designation that is approximately 11 times foot candle. (11 lux = 1 foot candle or lumen)

K or Kelvin degree is a measurement of the color of the light, not the temperature. 5550K and above is a blue-white light color, similar to the clear blue days of spring and early summer.. This is your veg light or metal Halide. 2200 to around 3500K is your bloom lights – reddish, warm, and midsummer to fall-like.

There are a few questions you need to consider:

1. Seeds or clones?
2. Do I want to eventually raise a donor or mother plant to ensure I have crop after crop of identical plants?
3. Do I want to use the grow room for just one cycle (veg through bloom), or do I want to divide it so I have a vegetative room and a bloom room?
4. Dedication rises, and the cost rises. Do you have time and money for both?
5. Is there a way to vent heat?

Basically, lighting comes in two ranges, the vegetative and the bloom. The spectrum and time the light is on the trigger the plants to grow a certain way. With a very blue spectrum imitating spring, with long 18 hour days with 6 hour nights, the plants grow quickly, developing roots, stems, and leaves. When the plant is moved under a very red spectrum, delivered at 12 hours on and 12 off, these mimics fall, when an annual plant (that’s one that finishes its entire life in one season) must set seed to reproduce. Flowers are produced, which are the seed-making machines of the plant.

Metal Halide (MH) and T5 fluorescent bulbs produce the blue spectrum needed for vegetative growth. A start-to-finish should use an MH bulb with switchable ballast for ease of use and less disturbance for this phase of your plants.

A fluorescent setup with grow bulbs is good when there is a side-by-side (veg and bloom areas). T5s are the best to use – they can be placed very close to the canopy of the plants without burning them, and these bulbs deliver the light, both in wattage and lumens! They also give off little heat, use very little power, and are reasonably priced. Bloom bulbs in a red spectrum are available. They will provide some light for your plants, but your plants will not produce as you want. HPS will give you an A, while fluorescents are a C at best.

An HPS, or High-Pressure Sodium, a bulb is used for blooming, giving off a good strong red spectrum. Bulbs such as MH and HPS both require a ballast to operate. Simply put, the ballast converts the power coming from your wall to enough power to fire the bulb. A ballast must match the bulb in wattage, such as a 600watt lamp must use a 600watt ballast. 

Electronic ballasts vs. magnetic ballasts – which one for you? Both do the job, but otherwise have little in common.

Magnetic ballasts are driven by as plate wound with a metal wire. This metal wire used to be made of copper, an excellent conductor. Unfortunately, copper is too expensive, and most magnetic ballasts are now wound with aluminum, a good conductor with a lower melting point. An igniter, a capacitor, and a cooling fan make up the rest of it. Magnetic ballasts are heavy, hot, make some noise and are not as efficient as the electronic ones, but they are less costly and can be repaired for years.

Electronic ballasts work off circuit boards, and are encased in oil for cooling. They are quiet, lightweight, and efficient. Many are dimmable, or will run multiple wattages. You do not need to manually switch from MH to HPS. They cannot be repaired, but many have good warranties that the manufacturer honors.

Buy the best bulbs you can afford. Home Depot does sell HPS bulbs – for lighting warehouses or parking lots, not your grow room. Wrong color, wrong bulb, huge heat – and cheap. But WRONG. Light spectrum is fascinating, but complicated. Lots of info is available if you want to know the mechanics.

A MH bulb should last about 18 months, and a HPS about a year. Keep track of the age of your bulbs. They will still ignite, but the gases contained in the bulb will have deteriorated. Replace them. Never buy bulbs online. Used bulbs look the same as new.

HPS and Metal Halide lamps must be in a reflector. This usually comes with a built-in cordset, which plugs into your ballast. The lamp screws into the mogul base. 

Reflectors can be air-cooled, which means they are sealed, with openings in both ends to let air driven by a fan blow through the reflector and move the air out of the grow room using ducting. Air-cooled reflectors should be used at the higher wattages, or when a room is not normally very cool. Dust the lens frequently, as dust and debris will reduce your light. These are usually heavy, and do require good support. Rope Ratchet Light Hangers are safe, strong, and will allow you to raise and lower your reflector easily.

Open reflectors are available, but the heat cannot escape the grow room. Small wattage lights can use them, but air-cooled is the way to go. Open reflectors, such as wings, are inexpensive and effective, and very lightweight, but do have drawbacks. Exposed lamps are HOT and could burn your plants or you. The lamp needs to be dusted frequently, which means timing it just as the lamp goes on. And the heat stays.

There is still a lot of chatter about LEDs. True, the lights themselves are cool, but the ballast they screw into is cooking. The newest developments in LEDs have addressed the heat and color issues, and have raised the intensity due to larger bulbs. LEDs can solve a number of problems in an overheated grow room, but at a huge expense. Initially the effective LED systems start at $1400 and go up. The advantages are low heat and long life; the drawback is the astronomical expense.

Bad ideas for lighting:

1. Black lights

2. Compact fluorescent bulbs like you would use in a fixture at home

3. Incandescent bulbs of ANY kind

Lamp intensity doubles for every 6” closer an HID is to the canopy. Cooler running bulbs, even if of a lower wattage, that can be placed significantly closer to the canopy, might be beneficial.

Lights too close will cause leaf-rolling and stop growth. Eventually burn and desiccation will occur. The stress will finally kill it. Lights too far away cause stretching between nodes, which makes the plant too tall and sparse, resulting in a lot of work for little return.

Plants into deep flower will start dropping leaves, and put all their energy into production. This is when a dimmable ballast comes into play. The higher wattage and more lumens push the plants into overdrive.

LIGHT MOVERS

This track on the ceiling slowly moves a reflector along a straight path or around in a circle. You can place the light lower (check the lumen chart) and cover more plants. They are also ideal for a long narrow space. Since the lamp is moving, the plants receive light from different angles, reaching deeper. A 6’ long track can change a 1000w light’s optimum coverage of light from 36 to 72 square feet. 

ELECTRICITY AND SAFETY

Work backward when installing components or wiring something. Start at the bulb, go to the reflector and plug it into the ballast. Plug the ballast into the wall. The last thing you touch would be the plug into the wall. You’ll blow a bulb or fry a ballast otherwise. Never adjust a dimmable ballast when it is plugged in!!! 

YIELD

This is all about light absorption and availability. If pruned inadequately leaves will shade too many of the fruiting sites, resulting in tiny fruit, whereas with less “business” yet fewer fruiting sites, what you get are big, juicy tomatoes instead of small, tasteless ones. The crops might weigh the same, but the quality of the big ones, and ease of harvest, makes the choice a no-brainer.

PHOTOPERIOD

Vegging requires 18 hours of light, 6 of darkness. Some folk swear by the 24 hours of light during veg, but the plant needs the dark to stop the business of photosynthesis and get on with transpiration and the coversion of the gathered energy into fuel, otherwise known as sugars.

Blooming cycle goes to 12 hours of light, 12 of darkness.

The new strains of dayneutral fruits and veggies are often called “autoflowering” because of equatorial genetics. They have a built-in timer because the day and night length are the same, and the light color is constant. You have no control over the cycle; the plant will bloom no matter what you do Dayneutral strawberries have been around for a while. This dayneutrality is very effective for outdoor growers with short natural growing cycles, such as those areas in the far north.

Interruption of these photoperiods is tolerated in the veg cycle, but in the bloom cycle it is critical. Even tiny, constant light, such as coming in under a door, will cause the plants to revert to the veg state in 3 to 5 days. These plants will have to remain in the bloom room for 4 to 6 additional weeks before harvest. Be diligent.

You can work after your lights are out with the use of a green LED headlamp. Plants do not “see” green. Don’t do this on a regular basis: emergency only.