Light is one of the basic requirements to grow weed and it is important to get this right. Marijuana plants need different parts of the light spectrum to grow, from blue light during their vegetative stage and yellow, amber, red and far red light during the flowering or bud stage, marijuana needs light between 420 and 750 nanometers (nm), note that the well respected McCree scale from Utah Stat University shows the light spectrum for all plants starts at 375 nm, marijuana is closer to 420 nm.
There are many types of grow lights on the market – let’s take a look at the most popular four.
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LED grow lights – Recently, modern technology has finally brought the ideal light to the market. Broad spectrum LED lights really do offer it all to the indoor marijuana grower. LEDs offer power consumption at approximately 15% of a similar HID, long life span of around 50,000 to 60,000 hours, no ballasts, no maintenance costs, no excess heat produced and effectiveness in all stages of the plants life. Broad spectrum LEDs are our pick for indoor growers who want a simple straight forward setup whilst maximizing space requirements and minimizing heat and electricity costs. Read more about LED grow lights.
HID grow lights – High intensity discharge grow lights (HID grow lights) are the industry standard used by every generation right up to now. It is a fight between HID and LED these days and the LEDs are winning the race in recent years only. HID used to be the most efficient way of transferring electricity into light; you might have seen them in use at stadiums and tennis courts. However LEDs are more efficient at turning electricity into light these days and that is why you are seeing LEDs make their way into car headlamps, yachts, street and stadium lighting.
There are two main types of HID marijuana grow lights; High Pressure Sodium (HPS) grow lights and Metal Halide (MH) grow lights.
Metal Halide (MH) grow lights emit light with a lot of blue in the spectrum. This makes them ideal for vegetative growth however they are not very efficient lights during the flowering stage. Many growers use metal halide lights just for the vegetative grow phase and then switch to high pressure sodium (HPS) grow lights for flowering. Using a mix of both lights throughout the entire grow is one of the optimum ways of providing light for your plants. More detail on MH grow lights.
High Pressure Sodium (HPS) grow lights emit the familiar orange or amber light you might see in street lighting. This light spectrum (yellow, orange, red) is the most effective for the flowering phase of growth. Although HPS grow lights are not the optimum light for vegetative growth they work very well and are the most popular type of grow light for anyone who may be limited by budget to just one lamp. They also run more efficiently than metal halide lamps, emitting more lumens for the same Wattage. If you are only going to use one lamp and have not considered LED grow lights then this is the one for you. More detail on HPS grow lights.
Fluorescent and CFL grow lights are now a little more popular to growers due to their compact size. Bulbs usually either target the blue spectrum used in the vegetative stage or the amber / red for the flowering stage however there are a couple of broad spectrum units available which should be suitable for growing marijuana from seed to flower. Fluorescent bulbs are available in a variety of types, roughly speaking they can be categorized into cool, warm and daylight light spectrum’s The daylight (white light) types work best but a mixture will also suffice. They are relatively cheap to buy and don’t need a ballast while their low heat output means fluorescents can be placed in very close proximity to the growing plants, indeed this is advised as their actual light output (measured in lumens) is quite low. Many growers use fluorescents for seedlings and young plants as their light demands are lower but there are better all round solutions like LEDs. Read about the new CFL compact fluorescent grow lights.
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