June 18, 2024 
Growing cannabis in a greenhouse offers the best of both indoor and outdoor cultivation methods, allowing you to harness natural sunlight while controlling environmental conditions. Greenhouses provide a protected environment that can extend the growing season, improve plant health, and increase yields. This comprehensive guide will take you through every step of growing cannabis in a greenhouse, from choosing the right structure to harvesting and curing your crop.
Before diving into the specifics of greenhouse growing, it’s important to understand the benefits this method offers:
Greenhouses allow you to control temperature, humidity, and other environmental factors more effectively than outdoor growing. This control helps prevent common issues like mold, pests, and extreme weather damage. For example, shade cloths and ventilation systems can prevent heat stress, while heaters can protect plants from unexpected frosts.
Greenhouses can extend the growing season by protecting plants from early frosts and allowing for earlier planting in the spring. This extended season can lead to multiple harvests per year, maximizing your yield. For instance, in regions with harsh winters, greenhouses can enable a spring and a fall harvest, effectively doubling your production capability.
Using natural sunlight reduces the need for artificial lighting, which can be expensive and energy-intensive. Sunlight is also more beneficial for plants as it provides a full spectrum of light that is hard to replicate with artificial light. Additionally, plants grown under natural sunlight often exhibit stronger growth and more robust terpene profiles.
For growers concerned about privacy, greenhouses offer a discreet way to cultivate cannabis. The structure can shield plants from view and help comply with local regulations. This is particularly useful in areas where outdoor growing is restricted or where discretion is necessary to avoid theft or legal issues.
Greenhouses can create an ideal growing environment that reduces stress on plants and promotes healthy, vigorous growth. The controlled conditions can also lead to higher yields and better-quality buds. For example, maintaining consistent humidity levels can prevent mold and mildew, while controlled temperatures can optimize photosynthesis and growth rates.
The first step in growing cannabis in a greenhouse is selecting the right structure. Several types of greenhouses are suitable for cannabis cultivation, each with its advantages and disadvantages.
Cold-frame greenhouses are simple, low-cost structures made from a frame covered with a transparent material like plastic or glass. They rely on sunlight to warm the interior and are best suited for moderate climates. Cold frames are typically used to extend the growing season by protecting plants from early frosts in spring and late frosts in fall.
Hoop houses are semicircular structures made from metal or PVC pipes covered with plastic sheeting. They are more durable than cold frames and can be equipped with ventilation systems to control temperature and humidity. Hoop houses are popular among small-scale growers due to their affordability and ease of construction.
Polycarbonate greenhouses use twin-wall polycarbonate panels to create a more insulated environment. These greenhouses offer better temperature control and are more durable than plastic-covered structures. Polycarbonate panels diffuse light more evenly, reducing the risk of hot spots that can burn plants.
Glass greenhouses are the most durable and provide excellent light transmission. They are more expensive to build and maintain but offer superior environmental control and longevity. Glass greenhouses are ideal for serious growers who plan to cultivate cannabis long-term and require precise environmental control.
Geodesic dome greenhouses are spherical structures that offer excellent light distribution and structural strength. They are more complex to build but can withstand extreme weather conditions. The unique shape of geodesic domes allows for better air circulation and more even heat distribution, making them highly efficient.
Choosing the right location for your greenhouse is a crucial step in ensuring the success of your cannabis cultivation. The location will affect various factors such as light exposure, temperature control, accessibility, and overall plant health. Here are key considerations to help you select the ideal spot for your greenhouse:
Optimal Sunlight: Cannabis plants thrive on ample sunlight, which is essential for photosynthesis and healthy growth. Ideally, your greenhouse should be located in an area that receives full sun for at least six to eight hours a day. Southern exposure is typically best in the Northern Hemisphere, as it maximizes sunlight during the day.
Avoiding Shade: Ensure the greenhouse is not shaded by tall trees, buildings, or other structures, especially during peak sunlight hours. Shaded areas can reduce light intensity and negatively impact plant growth and yield.
Sheltered Spot: While good ventilation is important, excessive wind can damage plants and disrupt temperature and humidity control. Choose a location that offers some natural wind protection, such as behind a hedge, fence, or building.
Windbreaks: If natural wind protection is not available, consider installing windbreaks such as fences or rows of shrubs to shield the greenhouse from strong winds. This will help maintain a stable internal environment and protect your plants.
Ease of Access: Select a location that is easily accessible for daily maintenance, watering, feeding, and harvesting. The convenience of access will save time and effort in managing your cannabis plants.
Proximity to Utilities: Ensure the greenhouse is near essential utilities such as water and electricity sources. This proximity will facilitate the installation of irrigation systems, heaters, fans, and lighting if needed.
Level Ground: Choose a flat, level area to set up your greenhouse. Uneven ground can lead to structural instability and drainage issues. If the ground is not naturally level, consider grading it before construction.
Soil Quality: If you plan to plant directly into the ground within the greenhouse, ensure the soil is of high quality and well-draining. Conduct a soil test to determine its suitability for cannabis cultivation and amend it if necessary.
Good Drainage: Ensure the selected location has good drainage to prevent waterlogging, which can lead to root rot and other issues. Avoid low-lying areas that are prone to flooding.
Rainwater Management: Consider the potential for rainwater runoff from nearby structures. Installing gutters and downspouts on the greenhouse can help manage rainwater effectively and prevent water accumulation around the base.
Privacy: If you are concerned about privacy, choose a discreet location that is not easily visible from neighboring properties or public areas. Privacy can help protect your crop from theft and comply with local regulations regarding cannabis cultivation.
Security Measures: Implement additional security measures such as fencing, locks, and surveillance cameras to safeguard your greenhouse and its contents. A well-secured location will provide peace of mind and protect your investment.
Microclimate: Consider the microclimate of the selected area. Factors such as temperature fluctuations, humidity levels, and frost pockets can vary within a property and affect plant health. Choose a location with a favorable microclimate for cannabis cultivation.
Local Climate: Learn about your region’s broader climate conditions, including seasonal temperature ranges, precipitation patterns, and potential weather extremes. This knowledge will help you prepare and equip your greenhouse accordingly.
Space for Growth: If you plan to expand your cultivation efforts in the future, select a location that allows for the potential enlargement of your greenhouse or the addition of multiple structures. This foresight can save time and resources in the long run.
By carefully considering these factors, you can select the optimal location for your greenhouse, ensuring a successful and productive cannabis cultivation experience. A well-chosen location will provide the necessary environmental conditions for your plants to thrive, leading to healthier growth and higher yields.
Once you have chosen and set up your greenhouse, it’s time to prepare it for cannabis cultivation. This involves creating an optimal environment for your plants to thrive.
While greenhouses rely primarily on natural sunlight, supplemental lighting can be beneficial on cloudy days or to extend the daylight hours in early spring or late fall.
Maintaining a consistent temperature is crucial for healthy cannabis growth. Cannabis thrives in temperatures between 70 and 85 degrees Fahrenheit (21-29°C) during the day and 60 to 70 degrees Fahrenheit (15-21°C) at night.
Cannabis plants prefer a relative humidity (RH) of 40 to 70 percent. High humidity can lead to mold and mildew, while low humidity can stress plants.
Proper ventilation is essential for controlling temperature and humidity and ensuring a fresh supply of CO2 for your plants.
Choosing the right soil and containers is critical for healthy root development and nutrient uptake.
The next step is selecting the right cannabis seeds and germinating them.
Once the seedlings have developed a few sets of leaves, they can be transplanted into larger containers or directly into the greenhouse soil.
During the vegetative stage, cannabis plants focus on growing leaves and stems. This stage lasts anywhere from 3 to 16 weeks, depending on the strain and growing conditions.
Ensure your plants receive at least 18 hours of light per day. If natural light is insufficient, supplement with grow lights. Consistent lighting encourages vigorous vegetative growth and prepares the plants for a successful flowering stage.
Cannabis plants require different nutrients at different stages of growth. During the vegetative stage, focus on providing higher levels of nitrogen, which supports leafy growth.
Keep the soil consistently moist but not waterlogged. Overwatering can lead to root rot while underwatering can stress the plants and stunt their growth. Monitor the moisture levels by checking the soil regularly and adjusting your watering schedule as needed.
Training techniques can help maximize yields and manage plant growth.
Keep an eye out for common pests and diseases. Regularly inspect your plants and take action at the first sign of trouble.
The flowering stage is when cannabis plants produce buds. Depending on the strain, this stage lasts 6 to 12 weeks.
Reduce the light schedule to 12 hours of light and 12 hours of darkness to trigger flowering. Consistent light schedules are crucial for inducing and maintaining the flowering process.
Switch to a bloom-specific nutrient formula with higher levels of phosphorus and potassium to support bud development.
Water needs may increase during the flowering stage. Ensure the soil remains moist but not waterlogged. Proper watering supports the plants’ increased metabolic activity during bud formation.
Reduce humidity to 40 to 50 percent to prevent mold and bud rot. Ensure good air circulation with fans and exhaust systems. Proper humidity control and ventilation are critical for maintaining healthy buds.
As buds grow larger, they may need support to prevent branches from breaking.
Continue monitoring for pests and diseases. Pay special attention to mold and bud rot, which can ruin your harvest. Regularly inspect your plants and take preventative measures to maintain a healthy crop.
Knowing when and how to harvest and cure your cannabis is crucial for maximizing potency, flavor, and overall quality.
Harvest time depends on the strain and growing conditions. Look for the following signs to determine when to harvest:
Drying is essential to remove moisture from the buds and prevent mold.
Curing improves the flavor and potency of your cannabis.
Light deprivation, commonly referred to as “light dep,” is a powerful technique used in greenhouse cannabis cultivation to control the photoperiod of plants. This method involves manipulating the amount of light your plants receive to simulate the natural light cycles of different seasons, thereby inducing flowering at specific times. Light dep techniques can help growers achieve multiple harvests per year, optimize yield quality, and improve overall plant health. Here’s a comprehensive guide on how to implement light dep in your greenhouse.
Light dep involves covering your greenhouse to block out light during part of the day, reducing the hours of light your plants receive. By controlling the light exposure, you can trigger the flowering stage of cannabis plants earlier than they would under natural light conditions. This technique is particularly beneficial for growers who want to produce high-quality buds outside the traditional outdoor growing season.
Multiple Harvests Per Year: By controlling the light cycle, you can force your plants to flower multiple times within a single year, significantly increasing your overall yield.
Enhanced Quality: Light dep allows you to harvest during optimal conditions, avoiding the challenges of late-season pests, mold, and weather issues. This can result in higher quality and more potent buds.
Consistency and Predictability: With light dep, you can schedule your harvests more precisely, ensuring a steady supply of cannabis throughout the year.
Pest and Disease Management: Early flowering and harvests can help avoid peak seasons for pests and diseases, reducing the risk of crop damage.
To effectively use light dep techniques, you need to create a controlled environment that allows you to manipulate the light cycle. Here are the steps to implement light dep in your greenhouse:
Lightproof Coverings: Use blackout tarps or lightproof fabrics specifically designed for light dep. These materials are durable, UV-resistant, and completely block out light when deployed.
Automated Systems: Consider investing in automated light dep systems that use motors and timers to deploy and retract the blackout coverings. Automated systems ensure precise light control and reduce the labor involved in manual covering.
Vegetative Stage: During the vegetative stage, cannabis plants require 18 to 24 hours of light per day. Ensure your greenhouse allows for maximum sunlight exposure during this period. Supplemental lighting may be used to extend daylight hours if needed.
Flowering Stage: To induce flowering, reduce the light exposure to 12 hours of light and 12 hours of darkness each day. Use the blackout coverings to create the necessary dark period. This change in light schedule will trigger the flowering hormones in your cannabis plants.
Consistency: Maintain a consistent light dep schedule to avoid stressing the plants. Inconsistent light cycles can lead to hermaphroditism or reduced yields.
Timing: Ensure the blackout coverings are deployed and retracted at the same times each day. Use timers to automate this process for accuracy and convenience.
Ventilation: Proper ventilation is crucial during the dark period to prevent mold and mildew. Ensure your greenhouse has adequate airflow, even when covered. Use fans and ventilation systems to maintain air circulation and humidity levels.
Environmental Control: Continuously monitor the temperature and humidity inside the greenhouse, especially during the dark period. Sudden changes can stress plants and impact growth.
Plant Health: Regularly inspect your plants for signs of stress or disease. Light dep techniques can increase the risk of mold and mildew if not managed properly.
Adjustments: Be prepared to adjust your light dep schedule based on plant responses and environmental conditions. Flexibility is key to successful light dep implementation.
Staggered Harvests: Plan your light dep schedule to stagger harvests. This approach ensures a continuous supply of fresh cannabis and allows you to manage drying and curing processes more efficiently.
Quality Control: Harvesting under optimal conditions, such as avoiding high humidity and pest-prone periods, can enhance the quality and potency of your cannabis.
Manual Labor: Manually deploying and retracting blackout coverings can be labor-intensive. Solution: Invest in automated light dep systems to reduce labor and ensure consistency.
Ventilation Issues: Inadequate ventilation during the dark period can lead to mold and mildew. Solution: Use fans and ventilation systems to maintain airflow and control humidity levels.
Light Leaks: Even small light leaks can disrupt the flowering cycle. Solution: Regularly inspect your greenhouse for light leaks and repair any gaps or holes in the covering.
Light deprivation techniques offer a powerful tool for greenhouse cannabis growers, enabling them to control the photoperiod and optimize harvest times. By implementing light dep, you can achieve multiple harvests per year, improve the quality of your buds, and manage environmental challenges more effectively. With careful planning and management, light dep can significantly enhance your greenhouse cannabis cultivation experience, leading to healthier plants and higher yields.
Growing cannabis in a greenhouse can present unique challenges. Here are some common issues and how to address them:
Growing cannabis in a greenhouse offers numerous benefits, including controlled environmental conditions, extended growing seasons, and increased privacy. By choosing the right greenhouse, preparing it properly, and following best practices for lighting, temperature, humidity, and nutrient management, you can achieve healthy, high-yielding cannabis plants. Remember to monitor for pests and diseases, use training techniques to maximize yields, and harvest and cure your buds correctly to ensure the highest quality product.
With the right approach and attention to detail, greenhouse cultivation can be a rewarding and productive way to grow cannabis. Happy growing!
Now that you know how to grow cannabis in a greenhouse, get your garden started by shopping the collection of regular, feminized, and autoflower cannabis seeds at Seeds Here Now.
Growing cannabis in a greenhouse offers several advantages, including a controlled environment, extended growing seasons, natural sunlight exposure, increased privacy, and improved plant health. Greenhouses protect plants from extreme weather, pests, and diseases while allowing for the use of natural light, reducing the need for artificial lighting.
When selecting a location for your greenhouse, consider factors such as sunlight exposure, wind protection, accessibility, ground conditions, water drainage, privacy, security, and climate. Ensure the location receives at least 6-8 hours of direct sunlight, is sheltered from strong winds, is easily accessible, and has good drainage. Additionally, choose a discreet spot to protect your crop and comply with local regulations.
Several types of greenhouses are suitable for cannabis cultivation, including cold frame greenhouses, hoop houses, polycarbonate greenhouses, glass greenhouses, and geodesic dome greenhouses. Each type has its advantages and disadvantages. Consider factors such as durability, insulation, light transmission, and cost when choosing the right greenhouse for your needs.
To prepare your greenhouse for cannabis cultivation, ensure proper lighting, temperature control, humidity control, and ventilation. Use high-quality soil or soilless mixes and choose appropriate containers for your plants. Implement a consistent lighting schedule, maintain optimal temperatures, control humidity levels, and ensure adequate air circulation.
Choose strains that are well-suited for greenhouse growing and your climate. Indica strains tend to be shorter and bushier, while sativa strains are taller and require more space. Hybrid strains offer a balance of traits from both indica and sativa. Consider using feminized seeds to ensure all plants are female and autoflowering seeds for a shorter growing cycle.
Light deprivation (light dep) techniques involve manipulating the light cycle by covering the greenhouse to block out light for part of the day. This simulates the natural light cycles of different seasons, inducing flowering at specific times. To effectively implement light dep techniques, use blackout tarps or lightproof fabrics, maintain a consistent light dep schedule, ensure proper ventilation, and monitor environmental conditions.
To manage temperature, use heaters in colder climates and shade cloths, ventilation fans, and evaporative coolers in hot climates. Maintain temperatures between 70-85°F (21-29°C) during the day and 60-70°F (15-21°C) at night. Control humidity by using dehumidifiers, proper ventilation, and adjusting watering schedules. Aim for 60-70% relative humidity during the vegetative stage and 40-50% during the flowering stage.
Common pests include aphids, spider mites, whiteflies, and caterpillars, while common diseases include powdery mildew, bud rot, and root rot. Prevent pests and diseases by maintaining proper humidity levels, ensuring good air circulation, regularly inspecting plants, using organic pest control methods like neem oil or insecticidal soap, and introducing beneficial insects like ladybugs.
Determine harvest time by inspecting trichome color (milky white with some turning amber) and pistil color (turning from white to orange or brown). Use sharp, clean scissors to cut branches or individual buds and trim away large fan leaves and smaller sugar leaves. Dry buds by hanging them upside down in a dark, well-ventilated room for 7-14 days. Cure buds by placing them in airtight glass jars, opening the jars daily to release moisture, and allowing fresh air in for the first 1-2 weeks. Cure for at least 2-4 weeks, though longer curing times can enhance quality.
Address temperature fluctuations by using heaters or cooling systems, manage high humidity with dehumidifiers and ventilation, control pest infestations with organic methods and beneficial insects, correct nutrient deficiencies with balanced feeding schedules and soil pH testing, and improve air circulation with oscillating fans and proper ventilation. Regular monitoring and adjustments are key to maintaining a healthy growing environment.
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