To start off the growing process, growers typically plant many seeds in small pots because you won’t know if all of them will sprout (or germinate), and you won’t know if all of them will be female (only females produce buds).
It’s hard to plan out your garden space and plant seeds directly into the ground if some seeds don’t make it; and you don’t want to plant a seed in a giant pot and potentially waste a bunch of soil if it won’t make it either.
So 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.
Check out these additional resources on soil and planting:
- How to choose the right container for your cannabis plant
- What’s the best soil for growing marijuana?
- How to make organic soil for your weed
Why is transplanting important
The main consideration when transplanting a weed plant into a new home is giving its roots enough space to expand. Roots need to expand and develop in order for a plant to grow and flourish. The container will determine the amount of space available for roots to grow.
When planting into the ground, make sure not to crowd your plants so their roots don’t run into each other. When root systems don’t have enough room to expand they become rootbound, and the roots become a big tangled mess, choking the plant.
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 underwatered. If a plant requires watering more than once a day, it may need to get transplanted.
You want a weed plant to be in its final pot with plenty of room for its roots before it enters the flowering stage.
When is the right time to transplant?
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 (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. Any discoloration or darkening may indicate that the plant has become rootbound, and a transplant should take place immediately.
- End of vegetative stage: Many growers opt to transplant to a finishing pot in the final two weeks of vegetative growth before a plant transitions into the flowering phase. At this point, a plant will explode both in size and volume and will require a substantial amount of space for root development.
How much space does cannabis need?
Not only do certain cannabis strains require more space than others, but outdoor growers need to work within their own garden’s parameters. How much room do you have available in your grow space?
When transplanting, give the plant at least double the space of its previous container. This reduces the number of times you must transplant, and minimizes the risk of transplant shock, which may occur when a plant experiences extreme stress from root disturbance.
Medium-sized indoor plants tend to be fine in a 5-gallon container as a finishing pot. For a plant of this size, you can germinate it in a 4-inch or one-gallon pot, and transplant it to a five-gallon pot before flowering.
On the other hand, large outdoor plants may require much bigger containers to reach their behemoth potential, sometimes up to 10-20-gallon pots.
When in doubt, always opt for slightly more space than needed. A plant tends to require 2 gallons of soil for each 6-12 inches of growth it achieves during its vegetative cycle. Knowing the potential height of the strain you’re planning to grow is a helpful consideration.
Check out info on a strain’s typical height on Leafly strain pages, under “Grow Info.”
How to transplant cannabis
The process of transplanting does not come without risk. Transplant shock can be incredibly detrimental to the growth and development of a plant, even deadly in some cases. However, through proper execution, the process of transplanting should benefit the plant, and lead to stronger root development and a healthier flower production.
Young plants should originally be sowed in a 4-inch pot, a Solo cup, or a one-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.
After checking the root development and confirming that the plant is beginning to fill the basin with healthy roots, it’s time to give the plant a new home.
- Wash your hands and/or wear gloves to prevent contamination of the delicate roots. 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 for enough space for the new plant; water in the soil here as well before moving the plant.
- Avoid overpacking the grow medium into a container during and after the transplant. This can compromise drainage and may damage root systems.
- Do not disturb or damage the roots when transplanting; the first transplanting poses the greatest risk for shock, and this occurs as a direct result of root damage and agitation.
- Avoid intense light when transplanting. This will help prevent transplant shock as well.
- Always fully water in the plant once it’s in its new home.
You may need to transplant your weed plant a second time to maximize its growing potential. Always monitor plants for symptoms of distress or overcrowded roots.
The finishing container is the final home for a plant until it’s harvested. This will be the largest container for a plant, and you always want to put it into this pot before the flowering stage. Transplant shock can cripple early flower development of a plant.
- Give the plant at least 1-2 weeks after a transplant before initiating flowering.
- Have plenty of space available in the final container for a plant to fully develop. For indoors, this generally means 3-5 gallons depending on strain selection. For outdoors, generally 5+ gallon containers are recommended (again, depending on the strain).
- Larger plants may require stakes and other supports to avoid structural damage during and after transplants.
This post was originally published on March 15, 2018. It was most recently updated on June 29, 2020.