Until about 30 years ago, if you were growing pot, you were growing it in the ground or plastic pots. Plastic pots were the agricultural industry standard for houseplants, small trees, and other flora. But due in part to the needs of cannabis growers, two new types of plant containers were developed. One type are white poly-plastic “grow bags.” The other type are cloth pots.

Plastic grow bags are marketed as being cheaper, more flexible, and they can be made in a white color that reflects sun or artificial light to reduce root zone heating. Plastic grow bags can be surprisingly sturdy. I’ve had some last outdoors in direct sun for a year or two, and indoors for several years.

Cloth pots were marketed as a root-boosting breakthrough because cloth allows intense oxygenation of roots. Roots need oxygen, so porous fabric walls were claimed as a big improvement over plastic pots. Cloth bags also have the advantage of having handles attached (although inferior brands don’t have handles).

And although I’ve never found a high quality pure white cloth pot, I have found them in a light tan color that absorbs far less light heat than black.

Cloth pot marketers claim that root growth, size, growth rate, and health are significantly superior in cloth pots compared to hard plastic or grow bags. But it turns out these claims are not always so true or proven.

Indeed, after years of doing comparisons between cloth pots and plastic pots, my conclusion is that cloth pots offer two provable advantages—they drain better than plastic pots, and they deter root circling and rootbound conditions.

Root circling creates rootbound conditions in plastic pots. Roots grow down and they also grow to the sides. When they hit the sides, they circle along pot boundaries, creating a tight weave of roots that gradually constrict newer roots, block water transfer, drainage, and aeration, and choke the plant from sides and bottom.

Growers who see leaf problems, low water usage, nutrients problems, slow growth and other problems sometimes fail to consider whether the container their plant is in has become too small for a developing root mass. They try a lot of other interventions (such as nutrients dosage or watering changes).

It’s easy to want to neglect the rootbound issue, because if your plants are rootbound, it means you have to transplant them to much larger containers. Worse yet, transplanting during bloom phase stresses plants, sometimes leading to hermaphrodite floral clusters and other stress responses such as slow growth or lack of floral potency.

Why is it that plants in cloth pots almost never get rootbound with circled roots? Because the intense oxygenation at perimeters of cloth pots creates automatic root “air pruning.” When roots reach the internal edges of a cloth pot, the oxygenation kills or redirects their growing tips back into the center of the root mass.

But it turns out this beneficial feature of cloth pots also creates problems. The main problem is the outer layer of root zone media along walls of cloth pots dries out much faster than internal layers, especially if direct light hits pots and/or if the garden’s relative humidity is quite low, or an aeration fan is blowing directly onto the cloth pots.

In my experiments, it looks like 5-15% of total media volume closest to cloth pot edges is much drier than rest of root zone. This reduces total amount of space available for healthy root growth, leading to a smaller root mass, which has negative consequences for your plants.

The drainage superiority of cloth pots can cause minor problems too. I’ve seen nutrients water run out of the sides of the pot first, never reaching the bottom. I’ve seen water drain out too fast, especially using inert media like perlite or peat-based mixes, leading to lack of moisture and nutrients in the root zone.

Both increased drainage and the perimeter drying issue mean you often have to water cloth pots more than you’d have to water the same size plastic pot. More frequent watering often necessitates adjusting nutrients dosage downwards to avoid nutrients burn.

Another problem with cloth pots outdoors is roots can grow through the bottom into the ground, and roots from the ground may grow into the pots. Roots can also become heavily matted and interwoven with fabric at the bottom of pots, impeding drainage and making it harder to remove a plant for transplant (because some of its roots remain embedded in the bottom of the pot).

And while it’s a great idea to reuse cloth pots, sometimes you can’t because it’s impossible to remove enough bottom roots that have grown into the cloth.

One other problem is algae and even mold can grow in the fabric if you’re overwatering, or growing in very high humidity. I wash my cloth pots and dry them thoroughly after every use.

As with most cannabis growing gear, there are a lot of crappy cloth pot brands and only a few good ones. The main problems with inferior brands include handles that fall off, bad stitching, cheap fabric that doesn’t last long enough, toxic fabric, fabric with insufficient porosity, pots are too short, wide, or tall, or don’t hold the media capacity specified. Looking at Amazon reviews for the various cloth pot brands gives you useful insight into brand quality.

I’m going to continue using cloth pots, but started buying larger sizes to make up for the lost root mass space due to edge drying. Given that five black plastic garden pots cost at least 2-3 times as much as reasonable-quality light-colored cloth pots, cloth pots are for me a good deal. Check out the videos embedded in this article too.