Grow Bags vs Plastic Pots: Which is Best for Cannabis?

The choice between plastic pots or fabric grow bags for cannabis might not seem super important. After all, weed can be grown in just about any container with enough care. But just because something is ”good enough” doesn’t mean it’s ideal. Let’s break down a few of the main features of each to get to the bottom of things.

One of the first choices you’ll need to make during any grow is the type and size of pot you’ll be using for your weed plants. No, I’m not talking about that kind of pot. Well, I am, but what I’m really referring to is the pot in which you’ll grow your pot. When it comes to pot pots, there are two main kinds; plastic and fabric. Both work, but which is right for you might vary.

Plastic pots: The long-time favourite

When you picture a flower pot, you’re probably thinking of the standard brown clay pots that make up the bulk of so many garden supply stores. While these are both functional and stylish, they are a poor choice for growing weed. On the whole, these pots are incredibly heavy and have rather poor drainage.

To that end, most cannabis growers made the switch to plastic pots. These are lightweight, durable, cheap, and can easily have extra drainage added if needed. Plastic pots offer a stable and rigid base to hold your growing medium and provide a durable barrier to keep unwanted contaminants away from your soil. Further, they come in several shapes and sizes and can easily be fit into any space.

However, plastic pots also have several important drawbacks that make them less than ideal for many growers:

Plastic is fairly brittle and can easily crack or break if mishandled. Even robust plastics are prone to cracking when filled with several kilograms of soil and being carried around.
The “durable barrier” I mentioned may actually be a bit too good at keeping things out. Plastic doesn’t breathe at all, meaning that your weed plant’s roots are less able to get oxygen. In extreme cases, this can lead to a plant becoming rootbound. This occurs when a cannabis plant’s roots grow too large for the container and is potentially fatal to the plant.
Plastic pots are harder to move around freely. Typically, these pots don’t have any handles and feature only a small lip at the top of the pot. If you’ve only got 1 or 2 plants, this isn’t a huge issue, but if you’re growing 30 weed plants in 20-litre buckets, the extra work adds up very quickly.

Grow bags: The new standard

While there’s nothing wrong per se with using plastic pots, most growers have found that fabric pots (also known as ‘grow bags’) offer just as many benefits without many of the drawbacks.

What are grow bags?

As the name might imply, grow bags are little more than fabric bags that you can grow in. Typically, these are made out of synthetic fabrics such as polyester or polypropylene and come in sizes from 4 to over 150 litres. While wrapping a bunch of dirt in a piece of cloth and throwing in some seeds and water might not sound like the best idea, there are several very good reasons for considering fabric pots that I’ll get into down below.

How long do grow bags last?

There’s no denying it: grow bags do not last as long as plastic pots; after all, plastic is notoriously hard to totally get rid of. If properly taken care of, a plastic pot can be washed and reused indefinitely making them a desirable option for those who hate waste.

Grow bags, on the other hand, are largely designed to be single-use. While it is completely possible to wash out a fabric bag and reuse it, the fabric will start to break down over time. With that said, you can easily get several uses without much trouble and some growers use the same fabric bags for years.

While polyester is still plastic, it can be recycled back into yarn, so these don’t need to be simply thrown away. However, not every location may be set up to handle polyester recycling. Check with your local recycling centres to see if they accept these bags.

Do grow bags need drainage holes?

Nope, not even a single one. Since they’re made of fabric, they are inherently porous, allowing for unmatched drainage compared to plastic pots. In fact, putting holes in your fabric grow pots is kind of a big no-no as it can allow foreign materials into the soil or enable the roots to grow out of the bag.

What do you put underneath grow bags?

Like any flowerpot, you’ll need to put something underneath your grow bags to collect runoff water. Any plastic tray will do and there’s no reason that you can’t use the same trays that you’ve been using under any plastic pots you may have.

Which is better: Plastic or fabric?

While what’s “best” will vary from person to person and grow to grow, there are a few things to consider including root development, aeration, drainage, and ease of use.

1. Root development

This might be the single biggest advantage of fabric grow bags. Cannabis plants’ roots will keep growing until they run out of space. If there’s no room left to grow, the plant will become rootbound, meaning there is no room left for the plant to grow. As the roots take over, the soil will be less able to hold water and the weed plant will slowly die if left untreated. In plastic pots, the roots will continue to grow until either A) the plant reaches its maximum size or B) it becomes rootbound.

Fabric pots, on the other hand, do not cause root binding thanks to something known as “air pruning”. When a cannabis plant’s roots are exposed to oxygen-rich, low-humidity air, they essentially get “burned” off. While burning your roots may not sound ideal, this is a natural process and encourages the roots to continuously grow new, healthy tips and prevent the plant from becoming rootbound.

2. Aeration

We all know that a cannabis plant’s roots need water, but they also need plenty of oxygen. Aeration is vital for the healthy development of a root system as it ensures the roots have access to oxygen. Just like their above-ground counterparts, roots require oxygen for cellular respiration, to convert sugars into energy.

In soil, oxygen is mostly found in the air pockets between particles. So, when soil becomes compacted, these air pockets are reduced and the oxygen available to the roots is greatly reduced. This can lead to root suffocation, reduced nutrient uptake, and overall poor plant health.

The breathability of fabric grow bags allows for unparalleled aeration to maintain a healthy balance of oxygen in the soil by promoting the exchange of gases between the soil and the surrounding atmosphere. This is especially important when growing indoors as soil can become compacted more easily when it’s in a single container. Grow bags, with their porous fabric material, promote natural aeration of the root zone, ensuring that cannabis plants have access to the oxygen they need.

3. Drainage

Plastic pots only have drainage holes at the bottom. While that’s certainly enough (for the most part) it’s not quite ideal. With only a single point of drainage, excess water is slow to leave and the soil can easily become waterlogged if not monitored closely. Overwatering is just as dangerous (if not more so) as underwatering and can be harder to fix, so preventing it is important.

Since fabric pots are porous all over, any excess water can drain from the most convenient place. Additionally, the increased aeration can help excess moisture evaporate from the sides of the pot. This, however, can mean that weed plants in fabric grow bags need slightly more frequent watering than those grown in plastic.

4. Temperature regulation

Fabric pots are ideal for temperature regulation, providing cooler roots in hot weather by allowing excess heat to escape through their breathable fabric. This prevents soil overheating, protecting the roots from stress and promoting healthy growth.

On the other hand, plastic pots tend to retain more heat which can lead to increased soil temperatures in hot weather, causing undue stress on the roots. While they do provide some insulation, plastic pots aren’t as effective as fabric, resulting in cooler soil temperatures in colder weather, which can inhibit root growth.

5. Ease of use

For starters, grow bags are incredibly lightweight. Not that plastic pots are heavy, but grow bags are certainly lighter. While this isn’t a huge deal, it’s worth considering if you’re going to be moving your plants often. Additionally, as I mentioned above, plastic pots don’t typically have handles which makes moving them in large numbers incredibly burdensome.

Further, since fabric pots offer better aeration and drainage, watering doesn’t need to be as precise. The odds of soil in a fabric pot becoming waterlogged are far lower (though the odds are never zero).

6. Root and soil stability

Going back to root development, plastic pots have one potentially hazardous flaw; the drainage holes. While these holes are absolutely necessary, they can cause certain issues. If a weed plant is getting a bit too large for its pot, the roots may begin growing out of the bottom of the pot through these holes.

If a plant’s roots begin growing out of the drainage holes, this can be a sign of imminent root-binding and the plant may need to be transplanted to a larger pot. If the roots are left to continue growing in this way, your weed plant is likely to experience serious moisture loss which can cause severe stress to a root system.

Lastly, open drainage holes can, in extreme cases, lead to soil erosion. This can in turn lead to nutrient deficiencies or cause the plant to become unstable in the soil.

7. Durability

While not as durable as plastic, fabric grow bags can survive multiple growing seasons with proper care. Their lightweight, flexible design won’t crack or break, making them safer to handle. Regular cleaning and inspection are key for maintaining their usability over time.

Plastic pots, on the other hand, are known for their durability and longevity. Plastic is generally better at withstanding environmental conditions, offering reliable support to cannabis plants. Plastic’s ease of cleaning and sanitisation allows for an even greater lifespan.

How to clean a fabric grow bag

Cleaning a fabric grow bag is very simple. After all, you’ve probably got a machine (or at least access to one) specifically designed for washing fabric. These bags are machine-washable as long you follow a few easy steps.

1. Preparation

Before washing, empty the grow bag of soil and any plant debris by simply shaking it out.

2. Machine settings

Put your fabric grow bags in the washing machine, preferably by themselves or with similar items like garden gloves or aprons. Use a gentle cycle with cold or lukewarm water to avoid damaging the fabric.

3. Mild detergent

Add a small amount of mild detergent to the washing machine. Avoid using bleach or harsh chemicals, as they can damage the fabric.

4. Washing

Start the machine and run it to completion. Once finished, remove the fabric grow bags from the machine.

5. Drying

Hang your bags to air dry. Avoid using a dryer, as high heat can damage the fabric. Ensure the grow bag is completely dry before storing or reusing it.

Bagging it up

Plastic pots have their place and if they’re what you have access to (or just what you have a strong preference for) then there’s no reason you can’t use them. However, fabric pots are overall a better choice as they offer improved aeration, durability, drainage, and root health. If you’re in the market for new pots, go for fabric.

Grow Bags vs Plastic Pots: Which is Best for Weed?

Plastic pots: The long-time favourite