Grow Tent Size for Indoor Growing of Cannabis, Vegetables, and Herbs

Indoor growers, today we’d like to talk about grow tents and grow spaces. If you’re growing indoors or are considering growing indoors, doing so in either a tent or a dedicated grow space is the best way to do it. A grow space can be anything from a closet to an entire garage or basement. Regardless of the area, there are a few things you’ll want to think about giving your plants the best possible chance of thriving.

Prefer to watch instead of reading? Check out our Youtube video.



The most essential function of an enclosed grow area is that the light, or photons, are kept there within. While this is a bit generalized and simplified, a tight grow space with reflective (mylar) walls will reflect light back into the grow space and increase the average PPFD (µmol/m2/s) by 10-20%. In other words, if you’re not using reflective walls, 10-20% of the light your grow lamp produces is wasted. 

Growing “in the open”, without reflective walls, a bunch of photons will find their way out from the area with plants and give little to no value. Keep in mind that photons are emitted by your grow light which uses electricity. Every wasted photon comes at a cost. 

As we want to make our indoor grow space as efficient as possible and maximize the output of our LED grow light, we want the highest number of photons to reach our plants.


Measuring PAR PPFD inside a grow tent


Using reflective walls or a grow tent is the first step. The second step is to make the grow area as tight as possible. Photons will not automatically land on your plants’ leaves just because they are reflected by walls. The photons could very well land on the ground, where they are also wasted. The longer the distance between your plants and the reflective walls, the more photons, or light, ends up away from the plants. 

The point we’re trying to make is that when you’re deciding what tent size to go with, or what grow space you’ll be using, try to estimate how large area your plants will occupy. Some growers let their plants grow au naturel (without bending, training, or trimming) while others, especially experienced growers, they manage their plants by bending, topping, and defoliating them to make them grow into a certain shape or size. Roughly put, a cannabis plant can occupy anywhere from a 1x1 sqft (30x30 cm) area to 3x3 sqft (90x90 cm) depending on how it’s managed, how large its pot is, and what conditions it’s grown with. Estimate how large are your plants will occupy and create your grow space as tightly as possible around this area.


3x3' vs 2x2' grow tent light distribution

PPFD PAR distribution in 3x3 vs 2x2 grow tent

Here's a PPFD/PAR value measurement of a 2x2' (61x61 cm) area. The left light footprint map is a 2x2' measurement within a 3x3' tent (outer 1' has been cut off) whereas the right footprint map is within a 2x2' tent. We see clearly how much higher intensities are reached within the 2x2' area. Point being: if you plants fit inside a 2x2' space but you use a 3x3' tent instead, a significant amount of light is wasted.

Another benefit of using an enclosed space is that light and smell (to some extent) is contained. Also, it’s easier to maintain desired humidity and temperature.

While a grow tent is an easy solution to the problem, purchasing mylar on a roll and dressing the walls of a grow space is also an option. Or, as we did in the video, cut mylar from a roll and fastened it with tape to plastic rods/pipes to create four moveable walls. Simple and cheap DIY solution.

To summarize: use reflective walls, whether it’s a grow tent or mylar strips, to maximize the light output from your grow lamp. Choose a tent or construct the grow space as tight as possible to force as many photons as possible to be reflected onto your plants instead of wasting them. Ideally, the leaves of your plants should nearly be touching the reflective walls.

Leave a comment

Please note, comments must be approved before they are published