Cloning is a popular way of asexually reproducing your favorite cannabis plants. Clones are possible because of a particular type of plant cell known as a meristem cell—building-block cells that haven’t decided what they are going to be when they grow up.
There are high concentrations of meristem cells in growth tips, but there are also meristem cells spread along the stalk. Normally, the meristem cells in the growth tips become shoots and foliage, and the ones in roots mature into root cells, and the ones along the stem develop into more trunk, but since all meristem cells start out the same, environmental conditions dictate what sorts of cells they turn into.
Clones are taken while the mother plants are in the vegetative growth stage, as much of the plant’s energy shifts to flower production once flowering starts. One way to think of clones is as parts of the mother plant. With cannabis plants, this comes in handy for gender determination and similar growth requirements.
Gender Determination of Marijuana Plants
Since they share the same DNA, the gender of both the mother plant and the clone is the same. A cutting from a female will be female, and a cutting from a male will be male. This knowledge can be used to sex plants: you can take a cutting and expose it to a flowering light schedule while the parent is left under growth lighting, and whatever gender the cutting displays will be the same as the plant it was cut from.
Since only the female cannabis plants develop buds, males can be eliminated from the growroom. This removes the need to cull males later, as the gender will have already been established. Once identified, superior females can be propagated by the garden-ful, if desired. By keeping at least one of a group of clones under a vegetative growth lighting schedule, more can be produced on demand.
Similar Growth Habits
A garden of clones should all have the same growth requirements as the mother, meaning less work customizing environmental conditions and nutrient schedules for different plant varieties.
When taking cuttings for clones, make sure each cutting includes at least one growth tip and a section of stem. The growth tip is important because the meristem cells there will lay the foundation for the upper portion of the mature plant. The root meristem cells will be missing, since the cutting initially will have no root system. Instead, the meristem cells in the stem are encouraged to develop into root cells as they age.
Each cut should be clean and handled with care, as it is an open wound. Since the cutting will no longer have access to the parent’s root system, if not used immediately, the cut end should be placed in water until planting. Although they may recover from a light wilt, cuttings are susceptible to terminal wilt. Once too many of the internal chains of water are broken, the cutting is no longer viable.
Fortunately, the meristem cells in a cannabis plant’s stems aren’t hard to coax into forming root cells. If the cutting is exposed to conditions that roots like, the meristem cells in the stem make root cells. The ends of the cuttings can be exposed to a plant hormone auxin such as idolebutyric acid (IBA) or naphthaleneacetic acid (NAA) to encourage root development, which is a key ingredient in many rooting powders, gels or liquids.
If the stem end of a cutting is placed in potting soil, a stonewool cube, rooting cube, mist or oxygenated water, put under moderate lighting in a warm environment and kept moist, in about 1-2 weeks, the cutting will form visible roots. The rooting medium should be pre-moistened before adding the cuttings, as if it is too dry, it can draw moisture out and encourage wilting. A large part of the art of cloning is keeping the stem and tip of the cutting alive and healthy long enough for the cutting to develop roots.
While cuttings need to be kept moist, overwatering is a more common problem than allowing them to dry out. Overwatering drowns sensitive cuttings and leads to fungal infections such as damping-off and root rot. Moderation is the key—the growing medium for cuttings should be kept moist, but not soggy.
Making Cannabis Clones
Armed with the tips above, here’s a step-by-step guide to making your own cannabis clones:
- Locate and prepare a space for the cuttings. It should have moderate light and be on the warm end of comfortable room temperature. A heating mat with a temperature sensor can help in cooler rooms. Make sure the area is spill-tolerant, so don’t place clones above electrical equipment or carpets.
- Prepare the growing medium and any containers. Make sure you moisten the medium appropriately.
- Using a sharp, clean instrument, cut a growing tip and section of stem off the mother plant.
- Place the cut ends into a container of water to keep them hydrated.
- Remove each cutting from the water in turn, apply a rooting hormone product and plant the end into the growing media or place into a propagator.
- If humidity levels are low, use a dome to minimize moisture loss due to evaporation, but ensure the moisture level doesn’t get so high it encourages fungal rots.
- Monitor and correct any moisture issues that arise until roots have formed. This may take 1-2 weeks.
- Once the roots are established, treat new clones as you would similar-sized seedlings, and enjoy the benefits of making your own clones from cuttings.