Ultimate Guide to Cannabis Pot Size

Does cannabis pot size affect plant growth? You bet it does! Container size makes all the difference for a good weed harvest.

The right size container is the first step toward successful cannabis plant growth that thrive and flourish.

Pot sizes vary greatly and are important to get right.

Whether you are growing one plant at home, or thousands of cannabis plants in a warehouse or outdoors, cannabis pot sizes make a big difference in the outcome of your yield.

But how do you determine the right size pots for marijuana growing? What are the advantages of one pot size over another?

Cannabis Root Needs

First, let’s talk about what a pot is meant to protect—the roots.

During the germination of a marijuana plant, the first thing that emerges from cannabis seeds is the plant’s central tap root. As the cannabis plant grows, roots and tiny hairs branch off of the central root.

A healthy marijuana plant will develop an underground structure that’s similar to the structure of the branches that are above ground.

Although you don’t see your cannabis plant’s roots, they require just as much care and consideration as the leaves and flowers. Cannabis plants breathe and absorb the nutrients they need through healthy root systems. They are fed through the cannabis roots.

So what do cannabis roots need to make plants thrive? Primarily, room for the plants to grow, proper draining, and no competition for nutrients. Growing cannabis can be easy if you make sure to check off all the right boxes, including the size of the pot.

Room To Grow

More than anything else, marijuana plant roots need enough space to grow properly in their environment. This is especially true in the vegetative stage of growth.

Root growth in the vegetative state is directly related to the plant’s ability to manage water and nutrients in the flowering phase.

If the container doesn’t have enough room, the cannabis roots become tangled together. This is known as “root bound” (or sometimes “pot bound”).

In pot bound plants, root development and growth is inhibited. If that happens, your marijuana plants won’t get the nutrients they need.

This can lead to nutrient deficiencies and lower yields. Make sure they have enough room if you want big yields for your cannabis plant and the cannabis roots are happy!

That said, there’s such a thing as too much room. If your marijuana plant is in a larger pot than it needs, your soil will stay wet. If you soak your plant, they are susceptible to root rot.

Good Drainage

To support healthy roots in cannabis plants your soil should stay a little wet. It should never be soaked.

Make sure your soil dries between each watering. It should retain just enough to keep moist and not be completely dry.

No overwatering! Waterlogged soil, excess water, and moisture can eventually cause root disease. Cannabis pots need good draining to keep dry. Get rid of most of the moisture when growing cannabis.

Avoid containers unless they’re designed specifically for growing plants.

A Solo cup might seem like a cheap solution, but when your crop fails and your plants die because of runoff water, you’ll see that isn’t the case!

And although a pottery bowl is pretty, it won’t look so great when it’s holding a dead shrub covered with pests!

Pots designed for growing have drainage holes in the bottom to manage water. Containers that are fabric or plastic that have holes everywhere are even better.

Place large trays or saucers under the pot to collect any excess water that drains out after watering.

If it’s not impossible, install a drainage system so that your plants never sit in stagnant water. If you can’t setup a drain, empty the runoff water from the saucers after each watering.

You don’t want excess moisture in your weed garden from water runoff when growing cannabis.

No Competition

Never put more than one weed plant in the same pot, no matter what size it is. Each cannabis plant should be contained in its own pot. If more plants are in a pot, the cannabis roots compete for the nutrients you pour in the pot. With this method, none of them will reach their full potential.

There’s another good reason to set a limit of one per container. If trouble occurs in one container (for example, build-up of toxic nutrient levels), you’ll only lose one plant. Plant pot in it's own pot!

What Cannabis Pot Size Should I Use?

Now that you understand what cannabis roots need, you can see why pot size is so important! But what pot size is best for growing weed?

Your marijuana plant will live in two or three separate containers during its life.

Seedling Phase

When planting cannabis, it's important to start small and gently nurture your seedlings. These young plants require extra care to get off to a strong start.

Use a seed starter kit specifically designed for baby plants during this delicate early stage.

Most cannabis seed starter kits include a tray with individual cells—place one seed in each cell.

They also come with a humidity dome and an air vent to regulate moisture, along with a bottom tray to catch any excess water.

Choosing the right growing medium from the beginning is key.

To prevent transplant stress, start your seedlings in the same type of medium you'll use throughout the plant’s life cycle.

If you plan to grow in soil, begin with soil. If you're using rockwool, use it from the start. Most starter kits are compatible with a variety of growing media, so choose what works best for your setup.

First Transplant

Seedlings are ready to transplant to a larger container when several white roots come out. If there are only one or two, the seedling needs more root development.

Transplanting success is closely tied with how quickly you deliver them into the containers. Work quickly! A good process is key. The tiny, exposed hairs will desiccate if they are exposed for more than two minutes.

Transfer the young plants to fresh soil in clean containers. Sprinkle some mycorrhizae fungi on the fresh soil before you transplant. The overlooked task of adding microorganisms will really help!

The first time you transplant, move your cannabis plant into a 2 to 5 gallon pot. How do you decide the right pot size? Which pot sizes are correct? Large container or small container? Here are some things to consider:

• Will you grow indoors or outdoors? If you’re growing inside, use a small container. If you’re growing outdoors, the sky (literally) is the limit! You won’t be limited in any way. That means you can use large pots when growing outside.
• If you’re growing marijuana inside, how big is your grow space? A full-grown adult cannabis plant takes around four square feet of space. That’s a lot of space—especially if you’re growing marijuana in a small space like an indoor grow tent. It’s vital to have easy access to your garden. Don’t let large pots get in your way. A grow tent pot size should be around 3 gallons (11 liters). You can reduce the size of your weed by limiting how long you keep it in the vegetative stage of growth. If you want to do that, go with a small pot or small pots. If you have more room, use large pots or a large container.
• What strains will you cultivate? Sativas tend to spread out a lot more than indicas. Since the cannabis plant root structure is similar to its branch structure, a sativa strain needs a bigger pot than an indica plant. Smaller plants need smaller pots. The cannabis roots will spread out. Keep it in mind.
• Do you want to maximize yields? If you want to produce as much weed as possible, you’ll need bigger containers to hold your massive plants!
• How much can you lift? If you’re not strong, use a small container. It needs to be light enough to pick up and move. You can’t do that with a heavy weight.

Can you flower in 1 gallon pots? You can, but it’s not a good idea. The smaller the pot, the faster growth cycle you should have. Note that when flowering in 1 gallon pots, the Screen of Green method is recommended. With big pots, you can veg as slow as you want.

Second Transplant

Outdoor growing gives you the freedom to do what you want. If you’re growing outdoors or in a huge indoor grow space, you aren’t limited at all!

You can let your cannabis plants grow as huge as you want (at least to the extent you can handle).

In this case, you may need to repot your weed more than once.

As a general rule of thumb, pot size should double each time a plant is transplanted for good balance. The bigger the plant, the bigger pot you need.

When you plant pot inside, remember that your ceiling height is important to keep in mind since when you move the plants from vegetative phase into flowering phase, the cannabis plants will double in height.

So what is the best pot size based on the plant size? Growing larger plants requires larger pots. Check out this plant pot sizes chart. It shows plant height to pot size ratio!

Transplanting can be stressful for cannabis plants, so it's often better to place them directly into the final container they'll use through harvest.

Giving your plants ample space from the start helps reduce stress, promotes stronger development, and sets them up for a more successful grow.

Best Grow Pots for Weed Plants

So many different cannabis pots are available for growing weed! The best pot material for growing weed depends on the grow system and soil that you’re using.

That said, don’t opt for materials like metal, clay, or terracotta. You’re better off with fabric pots that have more airflow.

Containers and pots intended for plants are constructed out a variety of materials, including terracotta, coir (coconut husk), plastic, ceramic, metal, wood, concrete, and rubber. The most economical, sturdy, and damage-resistant of these would be rubber or coir.

Rubber and plastic are probably the most widely used in nurseries and plants purchased for re-potting. A rubber plant container of the appropriate size makes a lot for sense for cannabis use. Many containers will shatter or chip with rough handling, but rubber bounces back and keeps performing for multiple grows.

Since nurseries rely on them so often, rubber pots almost always have adequate drainage and are able to retain moisture well.

Many cannabis growers have their personal favorites when it comes to cultivating cannabis, and compelling arguments can be made for each container medium, but there is much to be said for rubber or durable plastic, and these are the materials used most often.

Growing Media for Cannabis

Growing cannabis plants in pots requires a growing media. Straight potting soil is the simplest, most widely available choice. If you have access to compost, this is an excellent way to grow organically by adding it to soil for a nutrient-rich growing medium.

A variety of premixed soils with fertilizers already added are widely available as well. Some of these are organic, while others contain synthetic additives. The vast majority of cannabis growers prefer organic media.

Other materials sometimes added to soil include sand, perlite, and coco fiber. These substances provide a less-dense soil mixture than straight soil.

This type of mixture promotes rapid root development, which is always good for a cannabis plant’s overall health. Avoid soils that contain clay or other dense matter.

They will clog root development and retain too much water, neither of which is good for cannabis. Root growth is majorly important when growing marijuana and the grow media is important to assure proper root growth.

Regardless of which pots you choose for your cannabis cultivation, be sure to follow best practices and monitor your grow carefully. With attentive care, you can produce excellent flower with most pots. Use quality genetics, provide good care, and you will enjoy the rewards of your harvest on a relatively short amount of time!

The Right Weed Plant Pot Size

Strive for balance. While you don’t want to stunt growth with a small pot, an excessively large pot might result in overwatering. Ensure good drainage and consider the grow medium volume when deciding on pot size.

Master Grower Certification Online

Are you ready to get started on a career as a cannabis grower? Cannabis Training University will help you do it without being illegal!

Want to get growing cannabis for a living or just for your own personal home grow? Want to plant pot in a small space in your home and stop paying for it at dispensaries?

One plant or many plants, we teach how to grow pot plants in an easy step-by-step fashion. Learn how at CTU, the internationally accredited cannabis college!

Luis Cordova

Luis Cordova is a distinguished author, and renowned expert in cannabis cultivation, who possesses a Master's degree in Plant Biotechnology and Pharmaceutical Science. As a valued contributor to highly esteemed publications such as Cannabis Training University and Maximum Yield Magazine, Luis has emerged as a trusted source of guidance and knowledge in the cannabis industry. Having written thousands of informative articles, Luis is widely recognized for his comprehensive expertise on cultivating cannabis, both indoors and outdoors.