The Basics of Rooting Clones
Unlike growing cannabis during its vegetative cycle or its flowering cycle, cannabis that is being newly cloned does not have any huge light requirements. In fact, rooting clones is one of the few times when cool white fluorescents are one of your best options for lighting.
The light schedule for new clones is generally 16/8 or 20/4, though some growers will go 24/0 from clone through to the end of vegetative growth. A lighting cycle of 16/8, however, is quite sufficient for your new clones, especially when they are first rooting. During the first 2 weeks of rooting, you want your new clones to focus all their energy on developing their new roots.
To encourage the initial root growth, and to reduce the stress on your cutting, remove or trim any large fan leaves. Without roots, your cutting can’t support those larger leaves with nutrients anyway, so you’ll encourage and speed up root production by trimming those leaves off or down.
Depending on the medium you choose to root in (rock wool, peat moss, soil, aeroponics, etc.) the ideal pH may vary slightly, but generally you want to maintain a pH somewhere between 6.2 – 6.4. Proper pH is especially important during the rooting of new clones since the roots are literally just developing and are highly sensitive to the pH of their growing environment. When growing in peat moss, remember that peat tends to lower the pH, so your water and nutrient blend can potentially climb as high as 6.5.
Special Care for Rooting Clones
New clones love heat, especially down around the base where they are rooting. If you’re growing in a plug tray, or with rock wool or peat moss in a tray, consider putting a small heating pad under your tray on low heat. With or without the heating pad, be sure to maintain a steady temperature of 75 – 80 degrees Fahrenheit to ensure the best results with your clones. Drastic changes in temperature can stress and even kill your plants.
Alongside heat, new clones also love humidity. To keep your humidity levels up between 80 – 100%, a humidity dome is the perfect alternative to trying to make your whole grow room into a steam room. When you notice the humidity levels under your dome dropping, simply mist with some extra water inside the dome.
Be on the watch for mold when using a humidity dome, though.
Finally, as a general tip, remember to harvest 1 and ½ – 2 times the number of clones you actually need (so if you want 4, harvest 6 – 8 or even 10). This will allow for some natural loss to occur, and if you wind up with too many healthy plants after rooting, you can always give away the extras or donate them to medical patients who need them.