Marijuana cuttings will naturally root rather quickly if they are kept in perfect conditions and are prepared correctly. They don't have any roots, so their ability to get and maintain water is limited. In order to avoid a water shortage (a cause of wilting and, ultimately, death), you need to trim your plants well. The cuttings need to be 3 to 5 inches tall, and you should remove all leaves except for those in the crown. Those leaves should be trimmed to 1 or 1.5 inches in diameter.
Keeping both the roots and tops at a temperature of 72 to 74*F is ideal. That along with high humidity, moist rooting medium, and moderate light intensity that's high in the blue spectrum will encourage faster root growth. To begin, trim the cuttings. You may have heard that you can't cut them with scissors or that they must be cut underwater, but that's not true; you can use scissors.
Then, line up according to their crowns in groups of 10, and then cut the ends of the stems so that everything is equal in height. Dip them in a rooting solution or gel and then quickly place them in a sterile planting medium in 1.5- to 2-inch square pots or 1.5-inch square Oasis or rockwool cubes.
Keep the marijuana cuttings in a tray and ensure moisture with a clear plastic top. If the surface of the shelf is cold, you can insulate the tray with a Styrofoam sheet so that the temperature of the medium remains consistent with the surrounding air. If the temperature of the air itself is low, you may need to use a horticultural heating mat. When three days have passed, remove the top and irrigate the plants with a watering can.
Add hydrogen peroxide at a strength of 0.5%. The first watering should be unfertilized, but the second and third waterings need to have a flowering formula like 15-30-15 or 5-8-3 or something else that has a high phosphorous concentration (the middle number indicates the percentage of phosphorous) at 0.25-strength or a concentration of 400 parts per million (ppm). After that, start using a vegetative formula like 18-18-21 or 16-16-16 at normal strength.
Keep the garden lit up with 5,000 Kelvin fluorescent tubes like the GE Chroma or something similar. Keep about one tube per foot of width (e.g. a cloning space sized at 1' x 4' would be illuminated by a single 4-foot tube). If you're using compact fluorescents, use only one 13-watt lamp per square foot.
After about 7 to 10 days, the roots should start showing. At that point, you should increase the concentration of the vegetative formula to 800 ppm. If you want to wait to plant the marijuana clones, keep the lights at 10 watts per square foot. Usually, the plants will grow slowly, but, to increase their rate of growth, you should add more lighting tubes (around two tubes per foot of width). After doing this for week, you should have plants with vigorous new vegetative growth.