How and when to transplant cannabis plants

What is transplanting cannabis?

Transplanting is the process of “re-homing” a cannabis plant, or moving a plant into a bigger pot with more soil as it grows bigger.

Growers typically start off the cannabis growing process by planting many seeds in small pots because they don’t know if all of them will sprout—or germinate—and they don’t know if all of them will be female.

Only female cannabis plants produce buds, so if you start growing from regular seeds, you will have to sex them out and discard the males.

Why is transplanting marijuana plants important?

Transplanting gives a marijuana plant’s root system more space to spread out, allowing the plant to grow healthy and strong and to flourish.

When roots become cramped and can’t spread out they can get tangled and become “rootbound”—this will effective choke the plant, leading to a stunted, sickly plant, and can even kill it. A healthy root system will lead to a healthy weed plant.  

A plant’s container will determine how much the roots can stretch out, and therefore how big your plant will get. A container that’s too small will stunt it.  

You don’t want to plant a seed in a giant pot because you could potentially waste soil if the seed doesn’t make it. Also, if growing weed outdoors, it’s hard to plan out a garden and where to put your seeds in the ground if some seeds don’t make it.

Most weed growers start seeds in small 4-inch or 1-gallon pots when germinating.

For the seeds that do make it, they will need bigger homes after several weeks of growing and will need to be transplanted either into a bigger pot or directly into the ground.

When planting into the ground, make sure not to crowd your plants so their roots don’t run into each other.

The symptoms of a rootbound plant include:

• Flimsy new growth
• Stunted flower production
• Stem discoloration (reddening)
• Nutrient sensitivity
• Nutrient deficiency

A rootbound plant may also appear under-watered. If a plant requires watering more than once a day, it may need to get transplanted.

When to transplant marijuana 

Check out Johanna’s full video series on how to grow weed on Leafly’s YouTube.

Most marijuana plants go through 1-2 transplants during their life but could have more. As an example, transplanting can happen from: 

• First container (1-gallon) to second container (2-gallon): 4-8 weeks after seed germination
• Second container (2-gallon) to third container (5-gallon): transplant 8-12 weeks later, or 2 weeks before flowering

Some growers may only transplant once: using the example above, from a 1-gallon to a 5-gallon container, skipping the 2-gallon. And depending on how big you want your weed plants to get, you may transplant into bigger pots than what’s listed above.

The same goes for transplanting outside, in the ground—you can go straight from the first pot into the ground, but it depends on when you transplant and your local climate and weather.

Here are some indicators that your cannabis is ready for a new container.

Number of leaves

Young plants sowed in small containers are usually ready to be transplanted after they’ve sprouted 4-5 sets of leaves, but keep in mind this may vary from strain to strain.

Root development

Check the drainage holes at the bottom of the container—a plant should have a healthy and visibly white root system. If roots are growing out of the holes, it’s time to transplant.

Any discoloration or darkening may indicate the plant has become rootbound and a transplant should take place immediately.

End of vegetative stage

A weed plant should be in its final pot or in the ground with plenty of room for its roots before it enters the flowering stage. During flowering, a plant will increase in both size and volume, as the plant itself continues to grow and as buds develop. It will require a substantial amount of space for root development.

How much space does a marijuana plant need?

When transplanting cannabis, give the plant at least double the space of its previous container. This reduces the number of times you need to transplant and minimizes the risk of transplant shock, which may occur when a plant experiences extreme stress from root disturbance.

For example, you could go from a 1-gallon to a 2-gallon to a 5-gallon, or from a 2-gallon to a 5-gallon to a 10-gallon.

Medium-sized indoor cannabis plants tend to be fine in 5-gallon containers as a finishing pot. Large outdoor plants may require much bigger containers to reach their behemoth potential, sometimes up to 10- or 20-gallon pots.

When in doubt, always opt for slightly more space than needed. A plant tends to require 2 gallons of soil for every 12 inches of growth it achieves during the vegetative stage. Knowing the potential height of the strain you’re growing is helpful.

Why not start in the largest pot for your marijuana plant?

Growers typically transplant weed plants 1-3 times, moving plants to bigger pots gradually as they get bigger.

If a plant is put in too big of a pot, the roots won’t stretch out that much and won’t soak up as much water. This can cause water to sit in the pot for a long time, waterlogging the plant and leading to root rot.

You can transplant into the largest pot for your weed plant to avoid multiple transplants, but be careful not to water all of the soil—only water around the stalk of the plant where the young roots are.

How to transplant marijuana

Check out Johanna’s full video series on how to grow weed on Leafly’s YouTube.

The process of transplanting weed does not come without risk. Transplant shock can be incredibly detrimental to the growth and development of a cannabis plant, and can even kill it. However, through proper execution, the process of transplanting will benefit the plant and lead to stronger root development and healthier flower production.

First transplant of a cannabis plant

Young cannabis plants should start in a 4-inch or 1-gallon pot. This starting pot should be adequate for a few weeks before transplanting is needed.

Again, the first transplanting should occur after the seedling has sprouted its 4th or 5th set of leaves. To transplant:

• Wash your hands and/or wear gloves to prevent contamination of the delicate roots, and keep the surroundings as sanitary as possible.
• Give the plant a light sprinkling of water to help minimize shock; don’t drench it, as the soil will be difficult to work with.
• Fill the receiving pot with soil, allowing enough space for the new plant.
• Avoid overpacking the soil during and after transplanting—this can compromise drainage and damage the root system.
• Do not disturb or damage the roots when transplanting; the first transplanting poses the greatest risk for shock, which can occur from root damage and agitation.
• Avoid intense light when transplanting; this will help prevent transplant shock as well.
• Fully water in the plant once it’s in its new home.

Additional transplanting of cannabis plants

You may need to transplant your weed plant a second or third time to maximize its growing potential. Always monitor plants for symptoms of distress or overcrowded roots.

To do so, follow the steps above, and make sure the new container is at least twice as big as the old one, if not bigger. 

The finishing container is the final home of a plant until it’s harvested. This will be the largest container for a plant, and you always want to transplant into this pot 1-2 weeks before the flowering stage—you don’t want to disturb a plant while it’s flowering.

Keep in mind that large plants may require stakes or other support to avoid structural damage after transplanting.

Patrick Bennett contributed to this article.