Ventilation/Light for Growing Cannabis in Greenhouses
Some glass greenhouses are sold with a manual ridge vent, even when a mechanical system is specified, the manual system can be a backup system, but it does not take the place of a motorized louver.
Do not take shortcuts in developing an automatic control system. Evaporation cooling helps to eliminate excess heat in the greenhouse and adds humidity, reducing your plants’ water needs.
Misting and water are very important components of greenhouse gardening and extended periods of growing under high temperatures make water essential for your plants. Many companies offer water and misting systems that you can purchase for your greenhouse.
Installation of misting systems are rather simple, you can follow the directions on the system your purchase. If you are building a misting system of your own, you can use flexible plastic tubing, spray emitters, water pump, reservoir, and a timer to create your own.
Another lower-tech method of mist and watering control consists of a series of screens that tilt downward with the weight of the water shutting off the flow then rising to restart the cycle as the screens dry. Heating and water devices can be purchased and installed in your greenhouse to help reduce your daily work and focus more on your plants.
Though if it is going to be too expensive, you can always water and mist by hand, and control the heating of your greenhouse. In addition to shelter, heat, water, and ventilation, plants need sunlight.
You will want to make sure you purchase quality plastic or glass for your greenhouse as to keep the light quality high. Old color-changed plastics prevent a lot of beneficial light from getting to your plants.
You may also want to use supplemental lighting to increase your plants’ yield, many growers add fluorescent or HID lights. Another beneficial element to promote plant growth is the adding carbon dioxide to the greenhouse.
Enclosed greenhouses often lack in carbon dioxide, due to so many plants taking it up. Adding a CO2 burner, emitter, or even a wood burning stove will help increase the CO2 levels and therefore the growth as well as production of your plants.
Security is always a common concern when growing marijuana in a greenhouse so there are several ways that you will be able to camouflage your greenhouse. One simple way to camouflage your plants from viewing in the sky is to plant a variety of different plants (not cannabis) along with your marijuana plants.
You can paint the walls of your greenhouse with a paint that will allow light to come in, but a person will not be able to see through. Since you are growing in a greenhouse, you have a variety of ways that you can plant your cannabis plants.
To keep your plants organic, you can use raised garden beds, planting containers and even plant into the ground. Light deprivation is a method of growing where you darken the greenhouse during mid-summer to flower your plants.
Doing this method of greenhouse growing, you can harvest up to three (3) crops a year and with smaller greenhouses, you can manually cover and uncover the ‘blackout’ cloth over the greenhouse. With larger greenhouses, you can purchase or build systems that are set on a timer that will cover and uncover your greenhouse for you.
You can combine natural sunlight with artificial light to keep your plants in a vegetative state even though they should be blooming. Growers do this by turning on HID lights about 30-minutes before sunset, and for about 30-minutes after the sunrise.
This keeps the lighting cycle of the plants in the vegetative stage, keeping them from flowering so by doing this, growers can keep the vegetative photo-period of 16 – 24 hours of light a day going. With this method, you will be able to “veg” your plants through the beginning winter months and bloom them later.
Keeping the lights on in the middle of the day is not recommended, as it can cause additional heat stress on the plants and supplemental lighting has the greatest effect on younger plants and is more cost-effective when they are smaller.
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