Blue light – Grow lights with a higher ratio of blue light are often used in the vegetative stage as they tend to make cannabis plants grow short and squat, with big healthy leaves.
Yellow/Red light – Grow lights with higher amounts of red are often using in the flowering stage to encourage plants to grow tall (stretch) and to help promote budding. Plants may switch to the flowering stage faster under red light than under blue.
PAR vs Lumens: Which is Best to Measure Grow Light Intensity?
The light spectrum is a factor that cannot be ignored while you create an ideal environment for marijuana cultivation. Most growers have multiple goals like achieving high yields from their plants and increasing the THC levels. Improving and maintaining the overall health of their plants for indoor growing is crucial. Good growers need to involve in planning and coming up with technical solutions to achieve their goals. They should understand that adequate light is the one of important factors while growing marijuana plants. Colors of grow light are your secret weapon to produce more marijuana buds.
98% of the UV light that is reaching Earth contains UVA, which makes it an important part of the natural environment. If you are growing marijuana outdoors, you do have to worry about boosting UVA levels as your plants naturally receive plenty. UVA may help boost the THC level for indoor growth when you increase the exposure during the flowering period. However, for humans being exposed to UVA for long intervals can increase the risk of skin cancer. Therefore, you should make sure to protect yourself with sunscreen.
Red Light for growing cannabis
The energy emitted from the sun is in the form of radiation. The ozone layer filters this radiation and allows only wavelengths from 300-1100 nm to reach plants. This light is referred to as light spectrum, visible spectrum, or color spectrum. Its range is in between 380-750 nm approximately. A spectrum is a band of numerous colors namely red, orange, yellow, green, blue, indigo and violet.
The blue light spectrum is very important for marijuana plant growth. It is mainly responsible for increasing plant quality. During the vegetative stage of growing marijuana, you should aim for growing leaves as many as possible. The blue grow lights colors wavelength is from 450 to 490 nm. Indoor growers use T5 or T8 lighting fixtures, CFLs (compact fluorescent lamps), or metal halide bulbs that have a blue band of light. They use these for the first few weeks to achieve desired goals. When marijuana plants grow outdoors the angle of the sun during spring allows blue light energy which is abundant in this season to penetrate the leaves. Therefore, this blue light signals the plants to grow healthy and large leaves and to become strong. The plants that are deficient in blue light generally turn out yellow or pale and are weak and flopping. Blue light is essential for young plants and seedlings in vegetative stages to properly grow roots and stems.
UVA (315-400 nm)
Recent NASA findings suggest that green LED grow lights colors that are not majorly associated with photosynthesis but still have certain impact on the growth of plants. Green wavelengths have been considered less important when compared to chlorophyll absorption of blue or red-light spectrums. However, the green light can still play a role in the growth of cannabis plants at different stages. The wavelength ranges between 495 to 570 nm. Marijuana plants can absorb very little green light energy. However, reports say that a small amount of green light can affect growth. Many growers may think that the green light is unnecessary for successful growth. However, if you think of growing marijuana with lights having complete spectrums of colors then little green light energy is great for you.
What makes greenhouse growing a little more complicated, however, is that you have to do some calculations to figure out the balance between how much of what kind of light your plants are getting from the sun and how much artificial light you need to add in.
If you’re starting from seeds, you want to give your seedlings 24-hour light, but at low intensity. Stick to about 15% red and 30% blue and white. When your seedlings get their first set of true leaves, you can double the intensity until they have more than two sets, at which point they’ve graduated to the vegetative stage.
When we talk about the light spectrum, we’re speaking specifically about the distribution of red, blue, and UVB light. So the first thing to understand is how each color influences your plants. In the most basic terms:
The benefits of working with variable spectrum LED lights are huge. You can boost yields, create an even higher quality product, and drive profits through the roof.
If you grow in a greenhouse, you don’t need to bathe your plants in full spectrum light quite so often. The sun does a lot of the heavy lifting, so you only have to provide supplemental light. The benefit of greenhouse growing is that you spend less money powering your lights since they don’t have to be on at full intensity nearly as often as they would indoors.
Here’s what a typical growth cycle should look like:
Blue light is your secret weapon for amping up the concentration of oils and resin.
It’s impossible to provide any hard and fast rules for you in a single article because your needs depend on many variable factors. Where is your greenhouse located? What season is it? How long are the days in your region?
Of course, this is all strictly indoor lighting. If you’re growing in a greenhouse, the considerations are a little different.