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How to Make the Best Cannabis Growing Environment

Optimized Cannabis Growing Environment

A crop is more susceptible to pests, illnesses, and low yields the longer it is grown outside of its ideal environmental growth conditions. Growers of cannabis should carefully monitor the production environment to maximize plant health because the sorts of pesticides they can use are restricted.

Cannabis is a flourishing warm-weather crop, so prolonged exposure to cold, humidity, extreme heat, or dryness can throw the plant’s health out of balance. Thankfully, farmers of cannabis in controlled environments have access to a wide range of instruments and methods that may assist them in maintaining the ideal growth conditions for a robust harvest.

Do you have effective environmental controls? If not, utilize these target ranges to determine the ideal location for productive cannabis cultivation.


Bright light is ideal for growing cannabis, but not too bright, or you risk causing light stress. When growing indoors, cannabis plants need light; thus, the light they receive influences their harvests. Yields from small grow lights are often lower than those from larger ones when all else is equal. You need a large grow light to obtain exceptionally large yields of huge, fat buds. For instance, a grow light of at least 300W or greater is usually required to harvest one pound of cannabis, while a grow light of 600W is considered the minimum required to produce one pound of buds each harvest reliably.

Light influences how your weed plant grows. For instance, during the vegetative stage, plants grown in a light spectrum with a lot of red will become tall and lean, but plants grown in a spectrum with a lot of blue will become bushy and squat. Increased UV light is linked to stronger terpene synthesis during the flowering stage, whereas more red is linked to larger buds and increased potency in the buds. To ensure that your plants always develop to their full potential, several contemporary LED lights for cannabis use a unique color spectrum.

Light Intensity

During the vegetative stage, strive for an average light intensity of 300–700 micromoles, and during flowering, target a daily light integral (DLI) of at least 30. Higher light levels are beneficial to certain types while being harmful to others. To successfully develop a crop under high light, plants must first acclimate gradually and be exposed to more light over seven to ten days.

Here are some types of grow lights to use when growing cannabis:


Because of their excellent output, cost-effectiveness, and efficiency, HID (high-intensity discharge) lights remain the industry benchmark. Although slightly more expensive than fluorescent or incandescent light fixtures, they provide much more light for each watt of power utilized. In contrast, they are far less expensive than LED lights, although they are not as effective.

The two primary kinds of HID lights used in cultivation are:

  • Metal halide (MH) provides bluish-white light and is commonly employed during vegetative development.
  • High-pressure sodium (HPS) is employed throughout the blooming stage and creates light that tends to be on the red-orange section of the spectrum.

In addition to bulbs, HID lighting systems need ballast and a hood/reflector for every light. While many more recent models can operate both MH and HPS lamps, some ballast is made specifically for use with one or the other. Start with HPS bulbs if you can’t afford MH ones because they provide more light per watt. Although magnetic ballasts are less expensive than digital ballasts, they are less efficient, run hotter, and are harsher on your bulbs. Digital ballasts are typically a superior choice but can be a bit costly. Ensure you avoid cheap digital ballasts, which are sometimes poorly insulated and can cause electromagnetic interference that interferes with WiFi and radio transmissions.

Since HID bulbs emit a lot of heat, you’ll need to put your lamps in air-cooled reflector covers unless you’re growing in a wide, open environment with lots of airflow. It necessitates investing in exhaust fans and ducting, raising your initial costs but greatly simplifying temperature management in your grow area.

Fluorescent grow lights

Small-scale cannabis farmers are big fans of fluorescent light fixtures, especially ones that employ high-output T5 bulbs because:

  • They are typically less expensive to put up because the bulbs, ballast, and reflector are all packaged in one kit.
  • Since their heat generation is far less than that of HID installations, they do not need a cooling system.

The primary disadvantage is that fluorescent lights consume 20–30% less energy per watt of light produced; space is also an issue because 19 four-foot-long T5 bulbs would be needed to provide the same amount of light as one 600-watt HPS lamp.

LED grow lights

LED technology has been available for a long time and continues to improve efficiency. The primary disadvantage of LED grow lights is their expense: well-made fixtures can double or triple the cost of an equivalent HID system.

However, there are several advantages: LEDs have a far longer lifespan, consume significantly less power, produce less heat, and the finest designs provide a wider spectrum of light that can result in higher quality and larger yields.

Air circulation and exhaust

Cannabis plants develop more quickly if constant wind and fresh air are available. In addition, white powdery mildew, bud rot, and typical cannabis pests, including fungus gnats and spider mites, may all be avoided with good air circulation.

If feasible, you want the wind blowing over, through, and beneath your plants. It’s ideal if there is a gentle rustling of leaves. Not only should you avoid directing a fan directly at your plants to prevent windburn, but you should also avoid leaving any leaves in hot or stagnant air. One or two little oscillating fans may do wonders in the growing area.

When growing under lights, it’s crucial to release heat from them and ensure that the growing area is well-ventilated, particularly if the temperature becomes excessively hot. While many cannabis producers are aware that ventilation is necessary when using strong HPS lights, it’s also essential to remember that ventilation may be just as critical when using LEDs, LECs, or even fluorescent lights, such as T5s, if the overall wattage reaches a certain level. The greater the wattage, the more heat is created for each form of light.

light for growing cannabis

Remember, fans can circulate air but not reduce the room’s temperature. Ensure you consider venting heat out of the grow room to keep the temperature in check if it often rises beyond 85°F (30°C) despite fans. If the grow room’s general temperature continues to be too high, you might need to implement more serious measures, like purchasing an air conditioner.

Installing fans

Clip-on fans can be mounted to walls, corners, or support frames to provide ventilation in tight areas or tents. Use large floor versions or medium-sized oscillating fans for bigger grow rooms. It is important to arrange fans so that there is consistent, direct airflow across the garden. Usually, this calls for using many cooperating fans or fans with oscillation capabilities. Fans should not blast air directly into plants since this can create windburn, which causes leaves to retract into a claw-like distortion. Instead, there should be a pleasant airflow from above to below the canopy.


Your plants are most likely comfortable at a temperature that seems pleasant to you as well. Cannabis plants prefer temperatures between 65 and 85°F (19 and 30°C) and might get stressed when those temperatures are exceeded.

Aim for a maximum daytime temperature of 85°F and maintain overnight temps of 68 to 70°F. Cooler temperatures stimulate root infections, whereas, over 90°F, the plant enters survival mode. Steer clear of severe temperature swings, which might exacerbate crop issues like powdery mildew. Aim for the coldest and warmest times of the day to differ by no more than 10 degrees.

Controlling the temperature

You may regulate the following variables to get the ideal temperature for your indoor cannabis garden or grow room:

  • Lighting

Various grow lights will emit distinct heat signatures. Hot lights like MH, HPS, and fluorescents generate much more heat than LEDs. Additionally, lighting may be adjusted to boost or lessen the canopy’s temperature.

  • Air movement

Using fans and ductwork, you may drive heated air from the garden (down low) and replace it with cold air from above. Additionally, fans can aid air circulation within your canopy, which can chill the leaves.

  • ACs

If your grow area is too hot and the fans aren’t producing enough cold air, you might need to invest in an air conditioner to lower the temperature throughout quickly.

  • Heaters

Certain gardens need warm air, particularly at night when the lights are out and not producing heat.


Humidity often won’t have a significant impact on your cannabis growth unless it’s high or low. However, you can do quite a few things with humidity if you want your buds to develop quicker and produce more resin. Relative humidity ranges that container plants prefer to grow in are usually between 40% and 70%. An excessive amount of humidity can promote fungus, mold, and sickness. Dry weather might impede the growth of your houseplants.

Use a hygrometer to find out the humidity level in your growing environment. You can use watering systems, dehumidifiers, and humidifiers to get the ideal humidity level. Depending on the outside circumstances, you may achieve the ideal humidity balance in the growing room by opening or closing the entryway.

Thermometer and hygrometer for measuring temperature and humidity of cannabis
Thermometer and hygrometer in hand shows the temperature and humidity next to the cannabis or hemp plant. The humidity indicator is indicated on the hygrometer of the device

Monitor your cannabis plants for optimal humidity in every growth stage. During the vegetative stage, aim for 40-60%, flowering 40-50%, and the final weeks of flowering maintain 40-45% humidity. Remember, if the humidity is too high, your plants can exhibit slow growth and develop mold and bud rot.

Controlling humidity

Humidity is the amount of water vapor in the atmosphere. You cannot underestimate the importance of humidity when growing cannabis plants. Here are a few strategies to keep it under control in your grow room:

  • Dehumidifiers

Dehumidifiers raise the temperature while removing moisture from the air.

  • Air movement

Like managing temperature, you can also control humidity in your growing environment by controlling airflow. You can lower humidity by opening a place, such as your grow space or tent door.

  • Humidifiers

A humidifier can raise the moisture content by adding water vapor if a growing area is very dry.

  • Water

If you don’t have a humidifier, you may provide more moisture to plants by misting them with a spray bottle.

Maintain good CO2 levels

Elevating carbon dioxide proportionate to light intensity is a sensible guideline for reaching ideal amounts of this gas. Add as much as 700 ppm of CO2 to the air during vegetative development and 1,200 ppm during the flowering stage. Above that, greater temperatures would be required to guarantee the effective use of CO2 at elevated concentrations.

Reflection (which gives plants more light)

By directing all of the light at your cannabis plants, you can maximize the benefits of your grow lights. Use a reflecting substance to aim excess light from your grow light straight at your garden rather than allowing the walls of the grow chamber to absorb it. It lets you maximize yields from the same grow light without requiring you to make any further environmental adjustments.

Growing weed crops in a grow tent is the simplest method to obtain extremely reflective walls. Grow tent walls often have a reflectance of 95% or more. Still, you have a ton of fantastic alternatives if you’re developing in a do-it-yourself area. For instance, 85–95% light reflectivity flat white latex coating is a very affordable and simple wall material. Yes, it’s true—just painting your walls will double your cannabis production! Several different materials have excellent reflectivity; in fact, some professional alternatives perform much better than paint.

Creating the ideal growing environment

Understanding that there isn’t a single “perfect” growth environment is crucial. Like humans, every plant varies somewhat and could react more favorably in certain settings than others. Certain cannabis strains, for instance, are tolerant of extreme temperatures, and other plants don’t care as much about adequate airflow. However, regardless of the strain, you can guarantee that your cannabis crops will be comfortable by attending to the essential elements of a successful cannabis-growing environment. Of course, identify your sick cannabis plant as soon as possible if you have any issues!

Picture of Ed Rushford

Ed Rushford

Ed Rushford’s impact on cannabis growing is undeniable. Though he tends to focus primarily on 2 areas, plant training techniques and dealing with disease, pests, and other problems, he has offered many insights into how cannabis plants live and grow. That’s not to say that Ed is unfamiliar with the complete life cycle of cannabis, from seed to harvest, but he uses his widespread knowledge to hone in on the minutia and niche areas of growing cannabis. Ed’s goal is to spread knowledge and allow for everyone to become better growers. About this Author

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