Step One: Choose a mother plant that is at least two months old and 24 inches tall. Some varieties give great clones even when pumped up with hydroponics and fertilizer to grow fast. If a variety is difficult to clone, leach the soil daily with two gallons of water for each gallon of soil every morning for a week before taking clones. Drainage must be good. Or mist leaves heavily with plain water every morning. Both practices help wash out nitrogen. Do not add fertilizer.
Step Two: Older branch tips root easiest. With a sharp blade, make a 45-degree cut across firm, healthy 1/8 – 1-inch-wide branches, 2 – 4 inches long. Take care not to smash the end of the stem when making the cut. Trim off two or three sets of leaves and growth nodes so the stem can fit in the soil. There should be at least two sets of leaves above the soil line and one or two sets of trimmed nodes below ground. When cutting, make the slice halfway between the sets of nodes. Immediately place the cut end in fresh, tepid water to keep an air bubble from lodging in the hole in the center of the stem. Store cuttings in water while making more cuttings.
Step Three: Rockwool or Oasis™ root cubes cost a little more than soilless mixes, but are very convenient and easy to maintain and transplant. Fill small containers or nursery flats with coarse, washed sand, fine vermiculite, soilless mix or if nothing else is available, fine potting soil. Saturate the substrate with tepid water. Use an unsharpened pencil or chop stick to make a hole in the rooting medium a little larger than the stem. The hole should bottom out about one half inch from the bottom of the container to allow for root growth.
Step Four : Use a rooting hormone and mix (if necessary) just before using. For liquids, use the dilution ratio for softwood cuttings. Swirl each cutting in the hormone solution for 5 – 10 seconds. Place the cuttings in the hole in the rooting medium. Pack rooting medium gently around the stem. Gel and powder root hormones require no mixing. Dip stems in gels as per instructions or roll the stem in the powder. When planting, take special care to keep a solid layer of hormone gel or powder around the stem when gently packing soil into place.
Step Five: Lightly water with a mild transplanting solution containing vitamin B1 until the surface is evenly moist. Water as needed.
Step Six: Clones root fastest with 18 – 24 hours of fluorescent light. If clones must be placed under a HID, set them on the perimeter of the garden so they receive less intense light, or shade them with a cloth or screen.
Step Seven: Clones root fastest when humidity levels are 95 – 100 percent the first two days and gradually reduced to 85 percent over the next week. A humidity tent will keep humidity above 90 percent. Construct the tent out of plastic bags, plastic film or glass. Remember to leave a breezeway so little clones can breathe. If practical, mist clones several times a day as an alternative to the humidity tent. Remove any rotting foliage.
Step Eight: Air temperature should stay about 5 degrees cooler than the 75 – 80-degree rooting medium. Put clones in a warm place to increase air temperature and use a heat pad, heating cables or an incandescent light bulb below rooting cuttings. See drawing.
Step Nine: Some cuttings may wilt but regain rigidity in a few days. Clones should look close to normal by the end of the week. Cuttings still wilted after 7 days, may root so slowly that they never catch up with others. Consider culling out cuttings that root slowly.
Step Ten : In one to three weeks, cuttings should be rooted. Signals they have rooted include yellow leaf tips and roots growing out drain holes and clones will start vertical growth. To check for root growth in flats or pots, carefully remove the root ball and clone to see if it has good root development. For best results, do not transplant clones until a dense root system is growing out the sides and bottom of rooting cubes.
From: Cloning Step-by-Step, Excerpted from Chapter Nine, Indoor Marijuana Horticulture, The Indoor Bible
