Can You Use Black Lights to Grow Weed?

Growing cannabis is a fun and great learning experience. When preparing to grow the “green gold” known as marijuana, many supplies are needed to gain a fruitful harvest. If you’re new to the growing game, or just plain curious, you might wonder if you can use those old black lights from Halloween to grow your cannabis instead of spending cash on new LED grow lights.

You can not use black lights to grow weed due to the insufficient wavelengths in the light spectrum emitted by black lights. It’s also unlikely the black light would be intense enough even if it had the correct spectrum makeup.

Luckily, you can read my home page where I’ve listed the best grow lights available to grow weed. There are grow lights listed in every price range.

Important supplies such as pots, soil and lights are essential items when growing weed. Many people believe they can grow cannabis by using a blacklight, however; they’re many reasons about why it isn’t a great choice. Below I have listed 3 of the major reasons about why black lights aren’t a great option for growing marijuana.

Cannabis Plants Need Proper Light Spectrum

can you use black lights to grow weed

One of the main reasons black lights aren’t a great choice for growing weed is because they lack the correct light spectrum needed for growing cannabis. Cannabis plants grow based off two different colors of light, blue and red. During the early phases of a plant’s life, an extended period of blue spectrum light is needed for the plant to grow.

Grow lights attempt to mimic the sun with different colored wavelengths. The blue spectrum enables the plant to grow out and produce lots of leaves, both 3 tips and 5 tips leaves. When cannabis plants transfer into their flowering phase, they need less blue spectrum light and redder spectrum. The red spectrum light promotes tall growth and large buds. While blacklights emit some spectrum of blue and red light, it’s simply not enough to make the plants grow. Cannabis plants respond to brighter lights that have a higher lumen count. Lumens are the amount of visual light a lightbulb releases, blacklights don’t have a high number of lumens. The blue spectrum of a light encourages the plant to go through a procedure known as photosynthesis. Photosynthesis is a process in which plants turn full spectrum LED light (or natural sunlight) into nutrients to grow.

Black Lights Get Hot Fast

Weed plants don’t like climates too hot or cold, they prefer to grow in regulated temperatures. If the temperatures are too hot, the plants will mold, wilt and burn. Interestingly, if the room or selected climate becomes too cold, it will stun the growth of the weed plants and cause their cells to break down. Blacklights tend to bring lots of heat into the growing area, therefore, they make it hard to keep up a proper growing climate. Although blacklights tend to mimic the outside moonlight, the lumens within the bulb still aren’t enough to promote vigorous and healthy growth.

What Type of Lights to Use?

While blacklights aren’t suitable for growing weed, LED grow lights are designed exactly for that purpose. We wrote about the best LED grow lights on our home page. LED, COB LED, and Quantum Board lights work the best when growing weed indoors. Many people still use high pressure sodium or metal halide grow lights, but compared to the various LED models they’re not nearly as efficient.

Black lights produce a high number of lumens which makes them the perfect fit for getting the plant tall and bushy. Combined with one of the above-mentioned lights, a higher range of THC and CBD are present when using blacklights. Blacklights alone can be very harmful to a cannabis plant, however they help to pack on frosty trichomes during the last weeks of flowering when used with other lights.

Source: 420 Magazine

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