What is medium diffuse light for plants

The optimal lighting for cannabis plants - instructions

When growing cannabis, lighting is essential. The best possible lighting is natural sunlight. It has the perfect mix of UV rays that plants crave, and the closer you are to the equator, the better those rays get.

Cannabis needs a lot of light to produce high quality plants and flowers. On average, it takes twelve hours of darkness for a cannabis plant to bloom each day. In general, the more light your plants receive, the better and stronger they will grow, resulting in higher yields.

Having enough light isn't the only problem, however. There are four main aspects to consider when creating the optimal environment for your plants. These are:

  • The removal of the lamps
  • The intensity of the light
  • The color spectrum of light
  • Lighting cycles (lamps on - off)

So when you grow outdoors, nature provides what is needed for the plant's photoperiod. The color spectrum is of course regulated by the seasons and the lighting cycle is managed by day and night. Plants growing near the equator have the shortest distance and the highest light intensity.

However, if you grow indoors, you can control the photoperiod so that you can determine when your plants will bloom. Although sunlight costs nothing and provides the perfect light for cannabis plants, some places on earth just don't get enough sun for cannabis plants. If you live in such an area, it is probably best to grow your cannabis plants in a greenhouse with controlled lighting.

The use of grow lights

While growing outdoors has its advantages, some growers prefer grow lights as it allows them to better control their plants and the growing season. Just pointing any lightbulbs at your plants, however, is not enough to make them grow properly.

In order for the lighting to replace the sun, it must be provided with lamps specially made for growing cannabis.

How a cannabis plant grows depends on how the grow lights are used. The best lamp types are metal halide lamps, high pressure sodium lamps and now also special LED grow lamps.

Fluorescent lights are also good because they give off the best blue light for leaf growth. The MH lamps work best during the vegetative phase, while the ND lamps produce the best light during the flowering phase. The advantages of both lamps can best be used together.

Plant stagetimeLight colorLighting timeLamp spacingLight intensity
Seedling / cutting 1-2 weeks blue 24 hours of light Depends on the lamp Depends on the lamp
Vegetative phase 3-5 weeks Blue / orange 18 hours on / 6 hours off Depends on the lamp Depends on the lamp
Flowering phase 7-10 weeks Orange red 12 hours on / 12 hours off Depends on the lamp Depends on the lamp

The distance between the lamps is crucial for the growth of your plants. Too far away and your cannabis won't get the light it needs, but if these are too close you risk burning your precious plants.

During the seedling phase of your plant, it is crucial that you keep your lights at the correct distance. One of the biggest mistakes growers make is keeping the bulbs too far apart. This leads to "long" or stretched plants, with long weak stems (trunk) that cannot bear the weight of the plant and can kink upside down.

These elongated stems appear when the seedlings stretch up to get more light.

The actual optimal distance for your lights will depend on the type of light used and your grow room. Here are some basic guidelines:

Grow lamp power (MHL & NDL)The next one~ sunlightThe farthest away
150 watts 13 cm 18 cm 28 cm
250 watts 15 cm 23 cm 33 cm
400 watts 20 cm 30 cm 48 cm
600 watts 23 cm 41 cm 64 cm
1000 watts 28 cm 53 cm 79 cm

Plants that get more light tend to grow better and produce higher yields - that's a fact. However, it's also easy to oversaturate your plants with light and cause a slight burn. Or set the lamps too weak, so that your plants do not receive enough light and “stretch” or have stunted growth.

The light intensity or brightness can be measured both in lumens (lm) and in lux:

  • Lumens- measures the luminous flux emitted by a source. The higher the lumen, the brighter the light source.
  • lux- measures the intensity of light falling on a surface. Since plants only absorb the light that falls on their surface, light values ​​are usually measured in lux in grow guides.

Similar to removing the lamps, the optimal light intensity also depends on the type of light you plan to use in the grow room. Below are some guidelines to get you started:

Plant stagemaximumOptimalminimum
Vegetative phase ~ 70,000 lux ~ 40,000 lux ~ 15,000 lux
Flowering phase ~ 85,000 lux ~ 60,000 lux ~ 35,000 lux

Many people don't realize that the color of light can affect the growth of your plants. Visible light actually behaves like a wave and shows different properties depending on the length of its waves.

For example, a light with a wavelength of 400 nm is recognized by the human eye as a purple color.
Certain types of grow lights show a specific color of light. For example, MH (metal halide) produces a predominantly blue color light, while LED lamps can isolate and emit a wide variety of colors.

In terms of plant growth, blue light is best used during the seedling and growth stages as it promotes the formation of chlorophyll, a chemical that makes plants grow faster and stronger. MH lamps are often used for this because the blue light is supposed to mimic the summer months when the sun is high in the sky.

Conversely, HPS lamps mimick the end of summer, with the sun's rays traversing more of the Earth's atmosphere and showing a red spectrum that is ideal for cannabis plants to bloom.

The last but important component of proper lighting is the actual time your plants receive light. Just like humans, plants need their sleep and usually cannot be illuminated by light 24 hours a day. Also, lighting cannabis can get expensive when it comes to power consumption. This is another reason why it is a good idea to have a lighting cycle for your grow lights.

You cannot keep cannabis plants under constant lightbecause the plants will not flower without darkness. The only time the plants can be exposed to light for 24 hours is when they are in the seedling phase as they are still babies and need lots of light to grow.

In the dark, plants produce the hormones necessary for flower formation. If the darkness is not disturbed by light, they will continue to bloom and growth will be reduced to a minimum. You need a good combination of both to get a good harvest of marijuana.

For the duration of the vegetative phase, your plants need 18 hours of light and 6 hours of darkness. Once you are ready for your plants to flower, you can trigger their flowering phase by setting the lighting cycle to 12 hours of light and 12 hours of absolute darkness.

Learn more:

Don't waste light

As mentioned earlier, light is essential to growing high quality, high quality cannabis plants. Exposure to light triggers photosynthesis in the plants and if the correct type or amount of light is not used, this leads to the plant's growth stagnation. Unfortunately, many growers miss high yields because their grow setup wastes light.

If quality isn't reason enough to properly control your lighting, at least it could be cost. Cannabis relies on the hours of light it receives in order to grow effectively. But the cost of grow lights, along with the cost of electricity to use them, can get quite expensive. Fortunately, there are a few ways to increase effectiveness and thus reduce costs.

One of the easiest ways to do this is to make simple adjustments to your grow room / grow box. Use reflective materials and keep the cannabis plants as close to the wall as possible. This means that less light is wasted.

By carefully choosing the wall surface, you can increase the amount of light the plants can receive. The reflective materials help to reflect the passing light and direct it to the plants. It can also help illuminate areas that would otherwise be dark and provide light, heat, and energy for the lower parts of the plants.

The material you use on the walls of your grow room / tent can give off a reflective surface for light. Use a light meter to measure how effective a given material is. Measure by placing an opaque plate a few inches from the wall with the meter underneath.

The golden rule is to make sure that both measurements are the same distance from the light. If the light reflects off the different surfaces and is picked up by the meter, it should give different numbers for the two surfaces.

There should be a difference between these numbers - this difference shows how well your wall (or reflective material) reflects light.

It should also be noted that the wavelength of the radiant energy, also known as electromagnetic radiation, is 400 to 700 nm and the EM radiation is correlated with radiant heat energy, which has a wavelength of 800 to 2000 nm.

Create reflective grow rooms

If your current walls are not reflective enough, this is the place to fix! Here is a list of the most commonly used materials for the walls of a cannabis grow room:

This polyester film has a thickness of 1 to 2 mm and a high degree of reflection. There is also a more expensive and resilient version called Foylon that is easy to clean. Mylar is less durable, but it is far more reflective than Foylon. However, since Foylon is easy to clean, it may be a better solution in the long term.

The C3 anti-detection film is another type of mylar with the same qualities as the 2 mm thick. In addition to high reflection, it is also infrared-proof.

If you use one of these materials, good ventilation is required due to the high reflection of radiant heat. Don't create hotspots in the room when applying Mylar, Foylon, or C3 sheeting to the walls. To avoid damage, you can also use Velcro straps when attaching the foils to the walls. Make sure that no air bubbles form between the wall and the film.

Simple white color is also ideal for grow rooms. It's reflective, low-maintenance, and there is no need to worry about hot spots. However, you should add fungicide while painting. The color must be pure and flat.

Glossy colors and eggshell colors don't reflect as well. Also, make sure you don't get the walls dirty as this can reduce reflection. Titanium white is highly reflective but is rarely used due to its high price.

Elastomeric paint is another surface treatment that allows for good reflection. Since this is rubberized, it is quite durable. Reflective roof coating like the one from KoolSeal is a fairly inexpensive variant of this color. It forms an expanding and contracting rubber-like coating that is suitable for almost any surface.

The white or black plastic known as panda plastic or "poly" is an easy-to-clean surface for a temporary space. It doesn't damage walls and helps avoid hotspots, but it can melt if a light source is too close.

There are many options when it comes to the light from your cannabis plants. Everything from the type of lamp you use to the arrangement of the lamps will affect the growth of your cannabis plants. Setting up your lighting system perfectly is essential for a large yield. However, it may take a few tries to get it right.

If you don't want to experiment, you can also use a ready-made grow box. However, this is not absolutely necessary if you want to set up a complete room for your grow. With practice, you can learn how to create the best lighting for cannabis plants.

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