An artificial source of light is required when growing indoors and choosing the right lighting system is crucial for ensuring healthy growth and high yields. Plants require a certain colour spectrum of light to promote optimum levels of photosynthesis. A plant in a vegetative state will perform best under a blue spectrum of light, while the same plant in flower will perform best under a red spectrum of light. Light spectrum colours are measured in nanometers. Intensity of light is measured in lumens.
When selecting a grow light, consider the size of your grow space and the number of plants you’ll be growing. Make sure to select a light that provides adequate coverage for your plants, and adjust the height and intensity of the light as needed during different stages of growth.
In addition to the type of grow light, pay attention to the light cycle. Your plants require 12 hours of light and 12 hours of darkness during the flowering stage, and 18 hours of light during the vegetative stage. Use a timer to ensure a consistent light cycle and avoid interrupting the plant’s growth cycle.
Vegetative phase = 18 hrs per day.
Flowering phase = 12 hrs per day.
The distance between light and plant should be approx. 40cm for 400W, 40-60cm for 600W and 60cm for 1000W globes. Placing a fan gently blowing between the plant and globe will reduce the chance of overheating.
Fluorescent lamps are primarily used as a light source for seedlings and cuttings due to their low lumens per watt rating. There are a wide range of fluorescent tubes available, categorized by wattage, length, colour temperature and colour rendering index. The best suited tubes are those with a colour temperature of 5000 or greater, which is perfectly suited for early root and leaf development.
High Intensity Discharge or HID is the term for a gas-discharge light. Among the common types of HID lights are mercury vapor, low and high pressure sodium and metal halide lamps (see below). HID lamps produce light by sending an electrical charge or ‘arc’ between two electrodes and through an ionized gas which is housed inside the bulb.
HID lights require ignition which is usually provided by a voltage pulse or a third electrode inside the bulb. Once lit, the electrical arc begins to evaporate the metal salts inside the bulb, increasing the luminous power of the bulb and improving lighting efficiency. HIDs require a warm-up period because the lighting intensity is dependent on material inside the bulb evaporating into ionized gas.
As a HID light heats up, it requires additional voltage to operate. Voltage requirements in HID bulbs are managed by ballasts. As the HID light ages, more and more voltage is required to produce the same amount of light until eventually the voltage exceeds the fixed resistance provided by the ballast and the light fails. HID lights become less and less efficient over time because they must use more and more voltage to produce the same lumen output as the light degrades.
HID lamps are suitable for both the growth and flowering stages of the growth cycle. HID lamps have a higher lumens per watt rating than fluorescent lamps. HID lamps produce light by passing electricity through vaporized gas under high pressure. They require a precise starting technique provided through power boxes and special fittings and fixtures that house the lamps. Due to their high output, a large amount of heat is produced for every watt, so adequate ventilation is a critical when using HID lamps.
Metal Halide lamps create an abundance of blue light that makes them suitable for vegetative growth. Blue light promotes short internodal spacing and therefore excellent plant structure.
High Pressure Sodium lamps produce more yellow/red light which stimulates hormone production and a higher flower to leaf ratio. Therefore, they are perfectly suited for the flower stage of the growth cycle. HPS lamps have a higher output and last longer than Metal Halide lamps.
In our trials, we have found that HPS (versus MH), when used for an entire crop cycle, measurably out-performed MH. We have also found that HPS gives a marginally better yield when used for the bloom phase. In contrast, the MH performs slightly better during the growth phase. For best results use an MH for growth and an HPS for the flower phase.
LED stands for Light Emitting Diode. A diode is an electrical device or component with two electrodes through which electricity flows. Diodes are generally made from semiconductive materials such as silicon or selenium. When current passes through the semiconductor material the device emits visible light.
We have performed comparison tests using an ARCEYE LED 450w board vs a 600w/400V top of the range digital ballast. The 600w digital ballast produced an average of 0.5 grams per watt vs the ARCEYE 450W which smashed it out of the ballpark at a whopping 1.5 grams per watt! See Switching from HID to LED and LED vs HID to learn more.
LEDs have an extremely long lifespan relative to other lighting technology (including HID). New LEDs can last 100,000 hours or more. The typical lifespan for an HID bulb, by comparison, is 10-25% as long at best (10,000 – 25,000 hours).
LEDs are extremely energy efficient relative to other lighting technology. There are several reasons for this; they waste very little energy in the form of infrared radiation, they emit light directionally and they do not require additional voltage as they age.
LED technology has progressed significantly in the last few years. The new generation of LED panels blow every other lighting system out of the water! LEDs put off less heat, use less power, are smaller and more durable and they last longer than other forms of lighting. LEDs also offer a full spectrum of light, and some models even allow spectrum variability.
We highly recommend LEDs but suggest you exercise caution when purchasing. Avoid any purple coloured lights (Blurple) as they do not perform well at all! When purchasing LEDs we recommend panels with Samsung LM301H (or 301B) chips and a MeanWell Driver.
For best results, change your globes every 3000 hours. We have calculated a 10% loss between 3000-4000 hours and a 25% loss beyond 4000 hours. A light meter is a useful tool for measuring the loss of your globes. We recommend changing globes every second crop.
Reflective materials are not necessary. However, reflective materials on the walls reflect light, increasing growth and yield. Lighting your room will be more efficient with reflective walls. Check out our selection of reflective films.
Light spectrums that encourage terpene production are those that fall within the blue and red ranges of the visible spectrum. Blue light with a wavelength of around 400-500 nm and red light with a wavelength of around 600-700 nm are known to promote terpene production. In addition to the visible spectrum, ultraviolet (UV) light has also been shown to promote terpene production. Different strains may respond differently to light spectrums, so it’s important to experiment with different spectrums to find the one that works best for your specific strain.