Grindo: Indoor Quality, Outdoor Quantity, Greenhouse Grown

By Jonathan Valdman
Published: January 30, 2019 | Last updated: May 11, 2021 05:59:25
Key Takeaways

While it is debatable that this is the best approach to cultivating high-quality cannabis plants, Jonathan Valdman argues that grindo (greenhouse/indoor) growing—no matter the system used—offers the best of both indoor and outdoor growing.

For just a moment, forget about the immense amount of electricity that is used to grow cannabis plants strictly under lights. Forget about the fact that no bulb can replicate all the properties of the sun.


Remove the fact that the high cost of building an indoor growroom still leaves you dependent on either your local electric company or a fuel consumptive generator in order to run all the grow lights and fans.

These costs become so high that you might as well consider your local meter reader as a very silent partner that receives 20 to 40% of your harvest.


Toss aside the notion, if you will, that there is not one single agricultural crop cultivated commercially that is grown solely using artificial lighting.

Don’t even consider for the moment the environmental impact from bulbs that are improperly, or even properly, disposed of.

Now that we have stripped away some of the potential downsides to indoor cannabis cultivation, let’s consider some of the benefits.


Cannabis plant in an indoor growroom.Indoor growing allows plants to be grown in any geographic area, regardless of heat, humidity, cold, altitude, and other factors.

Benefits of Indoor Cannabis Cultivation

One benefit is security. Not only is your crop protected from unwanted visitors by a solid wall and a door, but you have complete control over your grow zone in other ways too.


This would include the control of the lighting schedule, which empowers the grower to determine the flowering schedules of their plants.

This allows for optimum efficiency of crop production throughout the year and allows the farmer the ability to bring product to market whenever they choose, often dictated by seasonal demands.

Humidity and wind velocity are also all easily controlled by fans that are monitored by an automated environmental control panel.

Temperature is controlled as well, so the outside climate has little to no effect (in the heat of the summer, the room is often cooled by air conditioning units, and winter-time lows sometimes see the need for heating units to keep the ambient room temperature up).

Though all these benefits do lend a sense of bling to crops grown indoors, it does leave open the conversation of what might be missing in a photosynthesizing plant that is using a bulb and not the sun for its main source of life force. Enter greenhouses.

Cannabis plants inside a greenhouse.Greenhouses can be used efficiently with ease and security by anyone with a green thumb and attention to plants.

Benefits of Greenhouse Cannabis Cultivation

Greenhouses offer up the control that indoor growrooms provide, as well as giving the plants the full spectrum of the sun that will increase the plants’ nutritional aspects and will dramatically increase your yield.

Traditionally used to extend your growing season through the cold of the off-season, greenhouses are now also being utilized with remarkable benefits during the rest of the year.

Indeed, greenhouses can be used efficiently with ease and security by anyone with a green thumb and attention to plants.

Most often when people think of greenhouses, they think of a wooden structure clad with old yellowing plastic or a mega gutter-connected greenhouse that covers acres of farmland with millions of dollars of investment glistening in the summer sun.

Read also: Greenhouse Glazing and its Effect on Photosynthesis

These structures might leave you feeling a little disheartened or with a feeling that a greenhouse for your own yard is out of reach.

However, there are greenhouse companies that specialize in customer service and making sure that you have the right fit for what you are looking for. Specifically, in our scenario, you need a greenhouse company that specializes in light deprivation.

Light deprivation techniques allow you the ability to step into the same game as an indoor grower while receiving all the benefits of greenhouse growing. Light deprivation is the ability to cut out sunlight from your greenhouse when you require extra hours of darkness to flower your plants while the outdoor light cycle is still in a period of vegetative growth.

Whether this is done with an automated light deprivation greenhouse or done manually by pulling tarps of a breathable blackout fabric, the end goal is the same: a consistent amount of required hours of light and of darkness, making your plants think fall and the end of their life cycle is approaching (therefore causing them to flower so as to continue the reign of their species).

A greenhouse company that specializes in light deprivation will have the knowledge of how to work most efficiently and effectively throughout the different seasons within your greenhouse.

Greenhouse with black tarp for light deprivationA simple light deprivation system is created in a greenhouse by covering the exterior of the unit in blackout tarps.

As I mentioned earlier, greenhouses have traditionally been used to extend your growing season early in the spring and late into fall and even potentially through the winter months.

This, however, does not address the harshest climate to deal with a greenhouse. The summer heat can become unbearable in a greenhouse that hasn’t been properly set up.

Read also: How to Cool a Light Deprivation Greenhouse

Solar gain is the term used for the increase of heat in a greenhouse from the inability to properly ventilate the space. A properly ventilated greenhouse will not exceed the temperature outside and will therefore not have much, if any, solar gain.

Proper ventilation can be achieved through exhaust fans or with passive cooling. When using fans, make sure to calculate the cubic foot dimensions of your structure and match it with fans that can exchange that air about every one to three minutes in the hotter parts of the year and two to four minutes for the rest of the year. (Cubic feet per minute [cfm] is the term the fan will use in determining how many cubic feet the fan can exhaust in one minute).

I prefer to use a dual fan/dual intake louver system so that the temperature and humidity can be controlled in stages. Also, take note that exhaust fans only work properly in a sealed environment; so, while leaving a door open or rolling up a sidewall might intuitively sound like a good idea, it isn’t always.

The fan will exhaust air from its closest location, so if there is an opening in the structure close to the fan, the fan will take the air from that point and not pull the air across the whole structure.

A greenhouse grower also has the ability to supplement the desired hours of light and warmth for the plant during the colder, darker months of the year. This can be done at a drastically reduced cost when compared to indoor growing because of their ability to use the sun.

Though the amount natural lighting might not be sufficient, you’ll only need a few hours of supplemental lighting in the beginning or end of the day in order to meet your daily quota of light and darkness.

Lights on inside a greenhouse at night.A greenhouse grower is able to supplement the desired hours of light during the darker months of the year.

On cloudy days, lights can also be used to increase the intensity of the light allowing plants to stay in optimal conditions.

As an added bonus, the winter sunlight also adds heat to your structure, thus reducing the need for a complete heating source. Many people heat their structures with overhead forced heat, although the more efficient and effective heat comes from the bottom up.

By heating the root zone, the most important part of the plant to stay warm, the heat will passively rise up through the canopy and start heating the rest of the empty structure (instead of starting in the empty zone of the structure that has a high level of heat loss).

This methodology can save thousands of dollars in heating costs. This bottom heat is usually done with water-based radiant heat.

Read also: Optimizing Climate in Your Greenhouse

A solar collector, a passive method of heating water from the sun, can be installed in the loop to heat the water before the boiler needs to expend energy heating the water on a cold but sunny day, saving you even more on utility expenses.

When looking at the methods of light deprivation, consider a high-quality polyweave, not film, covering that has the correct amounts of UV stabilization and the ability to diffuse light. These qualities in a fabric do a couple of things, most obviously is in the appearance of your finished product.

These fabrics were designed for the flower industry and the filtration causes plant resins to pop and wind up resembling plants that were grown strictly under lights. Also, the UV stabilization filters out the harmful intense spectrums of the sun that heat up your structure and your plants.

As such, this material lowers the temperature of your soil, causing less need for water and giving more optimal conditions to your soil microbes. It also reduces the temperature of the surface of the leaf, which is one of the biggest benefits.

The advantage to this is on hot summer days when plants outdoors are putting a lot of energy into transpiration, staying cool and survival, while the plants inside your greenhouse are putting their energy into photosynthesis, growth and flourishing.

Another bonus of greenhouse gardening is that you can use any system of growing that you would indoors—hydroponics, in bags, on tables, in beds, on a trellis system or vertical, the greenhouse structure is going to allow you to take what you’ve mastered and step it up to the next level in efficiency and production.

So, in a greenhouse, you can grow your plants like you would indoors... but at a fraction of the cost. Greenhouses excel in efficiency and offer a more complex finished product.

In a greenhouse, you have the ability to cultivate plants efficiently with indoor quality and outdoor quantity while greatly reducing your overhead and environmental impact to do so. So, go green and go outside while still being indoors—go into a greenhouse!

Read next: Indoor vs. Outdoor vs. Greenhouse Cannabis Cultivation


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Written by Jonathan Valdman | Founder

Profile Picture of Jonathan Valdman

Jonathan Valdman is an entrepreneur, consultant, and one of the industry’s most recognizable experts on permaculture, sustainability, and Best Management Practices. He has been farming organically for more than 20 years, and in 2006 founded Forever Flowering Greenhouses®, a commercial-grade greenhouse company that specializes in light deprivation growing techniques.

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