How, why, and when should you transplant marijuana plants?
If you’re growing marijuana in containers using soil, soilless mix, coco coir or similar materials (as compared to growing in deep water culture, aeroponics, rockwool slabs), transplanting marijuana is an essential skill.
Most marijuana growers put their seedlings or clones in small cups or pots to start with.
Obviously the plants can’t stay in those small containers all the way to harvest.
Why is it so important for you to transplant marijuana plants correctly and in a timely manner?
First of all, your marijuana roots by necessity want to get bigger and bigger so your aboveground plants can get bigger and bigger.
If your cannabis roots are trapped in a container that’s too small, your plants eventually slow or totally stop growing aboveground.
Even if you’re adding fertilizer, if your marijuana plants are growing in small containers, their roots will become rootbound so they don’t get enough nutrients, oxygen, or moisture.
Pretty soon, the cannabis roots become tangled around themselves and the plant aboveground suffers tremendously.
You transplant marijuana plants so below-ground root infrastructure can physically support aboveground infrastructure.
Your marijuana plants tend to overbuild aboveground structure relative to root structure.
I’ve seen marijuana plants in 2-3 gallon pots with 3-4 foot aboveground growth.
When those plants get into bloom phase, they fall over and/or their branches break because the pots and root systems aren’t big enough to counterbalance and support aboveground growth.
After years of experimenting with potting and transplanting marijuana plants, I’ve found a program that works well, and some general rules that apply in all container marijuana gardens.
First off, I start marijuana seeds or cuttings in root shooters, jiffy pots, or rockwool cubes.
Some marijuana growers start their plants in Solo cups filled with soil, soiless mix, coco, or rockwool.
As soon as my marijuana seedlings and cuttings have several healthy root strands of more than a half inch protruding from the cubes, I transplant into 1-3 gallon pots.
I used to transplant marijuana seedlings or clones directly into large pots (such as 5-10 gallon pots), assuming I’d save time on transplanting.
What I discovered is these large pots tend to get waterlogged when you use them for plants that are just staring out, with most of the moisture going into the bottom.
Marijuana root development in those situations wasn’t as dense as root development when I start with smaller pots and gradually transplant up.
If you really want to use transplanting as part of a professional marijuana plants management program, you transplant at least three times: once when your plants have developed enough roots to take them from where they sprouted or were cuttings.
Second, you’ll transplant them after they’ve been in grow phase for 3-5 weeks.
Third, you’ll transplant marijuana plants into a finishing container just before you put them into bloom phase.
The main thing is to pay attention to your marijuana roots to they guide you as to when to transplant.
Monitor container drain holes to see when healthy white roots are protruding from the bottom of the pot.
When you see a bunch of healthy white roots trying to escape from the bottom of your pots, you know it’s time to transplant.
Another “rule” is illustrated by this example: if my pots are 9 inches tall and I have 12 or more inches of healthy aboveground growth, this is when I need to do transplanting.
The generic version of this rule is you need one gallon of pot size for every foot of aboveground growth.
This rule also coincides with a calendar timing marijuana transplanting rule.
In most cases, I upgrade my cannabis plants from one-gallon pots to larger pots approximately 3-6 weeks after I transfer the seedlings or clones into the one gallon pots.
Another generic transplanting rule is you need at least one gallon of pot size for every month of plant growth through harvest.
Translated into an example: if you anticipate your marijuana plants will grow for 4-5 months before you harvest them, you need at least a 5-gallon pot as the final pot size your plants will finish in.
Remember if you’re growing in aeroponics, deep water culture, or nutrients film technique, transplanting your marijuana plants isn’t as necessary, and might not be necessary at all.
Now look at our next article in our series on transplanting marijuana successfully.