How to clone a marijuana plant
- Pick your mother.
Choose a strong and healthy mother plant that is at least two months old and is in the vegetative stage. Use about 10% less nitrogen on this plant in the weeks before cloning, or wash out excess nitrogen by misting the plant heavily with water for a week. Don’t add any fertilizer.
- Clean everything and get it ready to clone.
All your tools should be thoroughly cleaned and the cutting tools should be sterilized with a dilute solution of alcohol. Use gloves to handle the plants. Use a clean sterilized surface for trimming the cuttings.
- Cut the branch from the main stem.
Using a razor blade or a scalpel, make a clean cut at a 45 degree angle across the stem. Choose a stem from the lower part of the mother plant, because that is where rooting hormones are concentrated. The stem should be about 1/4 inch wide and firm with healthy leaves. Take care not to crush or pinch the cut end. Place the cutting in water immediately if you are making more cuttings.
- Trim and split the cutting.
Trim off the lower one or two sets of leaves so there is room to stick the cutting into the growing medium. Split the stem with your sharp blade for about 1/4 inch length, to expose the inner stem (cambium) which is where roots originate. There should be two sets of leaves remaining above ground, and two growth nodes (leaf stubs) below ground. Cut off about half the end of the above-ground leaves–you want big roots to grow, not big leaves.
- Use rooting gel sparingly
Use a liquid rooting gel and dip each cutting in the rooting liquid for 15 seconds. If you use power or solid rooting gel, make sure some sticks to the stem when you put it in the soil.
- Stick into your planting medium.
Rockwool or other root cubes are the perfect size for your cuttings. Make a hole with a pencil that is 1/2 inch shorter than the depth of the root cube. That allows roots space to grow. Make sure the planting medium is well saturated with water.
- Keep the cuttings moist.
Until there is a strong root system (day 7-14) you need to water the cuttings to maintain even moisture in the soil. Moist but not soggy. Too much water drowns the growing roots. Do NOT fertilize.
- Control light, temperature and humidity.
18-24 hours of light daily is best especially for the first week. An LED Grow Light with sufficient coverage for the square footage (footprint) of your tray of cloning cubes should give about 35-50 watts per clone. The light should be 16 -24 inches above the clones. Air temperature of 65 to 75 degrees F and humidity of 90-95% is best for the first week, until roots are visible.
- Transplant when rooted.
When the roots start to form a tangle on the outside of the rooting cube, it is time to transplant. Depending on the variety of the mother plant and the age of the clone cutting (top=old, bottom=young), the root tangle will be sufficient for transplanting around 2-4 weeks after cloning.
- OR–Get an all-in-one cloning kit.
MaryJane Farmer wrote a whole article with more details on cloning. The article includes information on rooting gels, cloning kits and the various paraphernalia you will need to clone your best buds.