Cultivating really high quality cannabis requires extremely good plant health. Most growers will transplant a seedling or clone at least once, and sometimes more often. Parental stock (plants dedicated as sources for cuttings) can undergo many transplants in its life. If you wait too long, or try it too early, you are almost certain to harm the plant in some way. However, the question remains – how can a grower tell a plant should be moved to a new pot?
First is to avoid transplanting too early. A cannabis plant should have grown enough roots to fully encase the soil. This doesn’t mean the roots need to be dense, they just need to be dense enough to hold the soil together.
Note the roots on this little lady. See how they are spreading out to fully encase the soil? This seedling is ready for transplant. As you can clearly see (pun intended), the use of transparent cups can be very helpful for the new grower. Should you transplant too early, the roots won’t be able to hold the soil together. The soil will fall apart when you attempt the transplant and you will end up with a mess on your hands and the roots of the plant will likely be damaged in the process.
It can be a little more difficult to determine in older plants, but they will tell you when it is needed, none-the-less. When a plant becomes root bound, the roots have taken up all available space within the soil and there is literally no more room left for roots to grow. If your plant is drying very quickly, it may be getting rootbound. If your plant is showing light green at the top, and wrinkly leaves at the bottom, it may be getting rootbound. If the lower leaves are looking blotchy (light and dark colors), it may be getting root bound. Clawing leaves usually accompany these symptoms as they become more and more rootbound.
Sometimes you can conduct the transplant before your medical cannabis shows any of these signs. This is great if you can accomplish it and they’ll experience even less transplant shock as an added bonus. My rule of thumb to accomplish this timing is the transplant when the plant is just a little taller than the pot is deep, and the leaves have extended past the edges of the pot. This is generally perfect timing, particularly in pots less than 3 gallons.
Do keep in mind that if your plant showed any of these negative symptoms prior to transplant, they may also show yellow spots in the week following transplant. These spots will eventually turn brown as well. Don’t worry, these are after effects of their prior condition. As long as the rest of the plant looks healthy, just snip the affected leaves and keep doing your thing.
Finally, I’ll remind the reader that the fewer times a plant is transplanted, the better. If you can plant a see directly in the pot it will finish in, that is ideal and will shave 3-5 days off the time-to-harvest. This isn’t always possible though so timing that transplant becomes important.
Happy Harvests!
— The Lit Farmer —