Arguably the most important, but also most difficult, stage to master in a perpetual indoor cannabis garden is the cloning stage. The majority of cannabis growers rely on the cloning process to provide future generations of plants for their gardens. One of the biggest reasons why the cloning process is so important to cannabis growers is because cannabis plants are dioecious plants. This means the male and female reproductive parts are on separate plants. Unless they are breeders, cannabis horticulturists are only interested in growing female cannabis plants. Cloning provides a way for cannabis growers to select the strongest and most productive plant varieties for replication, while ensuring the crop is made up of all female plants. As with other aspects of indoor cannabis gardening, consistent atmospheric conditions are the foundation for cloning success. Along with consistent atmospheric conditions, there are a few techniques a grower can implement to increase his or her cloning success.
Selecting the Mother Plant
One of the most important aspects of cloning is selecting an appropriate mother plant. It is imperative to select a mother that is in good health. If the mother plant has diseases, pest insects, or other pathogens, chances are good any clones taken from that plant will have those same problems. Once an appropriate mother is chosen, it can be prepared for cloning. One technique that can help increase a gardener’s cloning success is to limit the mother plant’s exposure to intense light for 24 hours prior to taking clones. This can be done by placing it in the outskirts of the garden or in a shaded location the day before taking cuttings.
Making the Cut
After selecting, inspecting, and preparing the mother plant, the grower may begin taking cuttings. Generally, it is best to make a 45-degree angle cut just above a node site (the place where a leaf or branch attaches to the main stem). If the grower wishes to use a rooting hormone or cloning gel, the freshly cut end should be dipped into the hormone right after it has been cut from the mother.
Auxin is a plant hormone that aids in the creation of initial root growth. Specifically, indole acetic acid (IAA) is the natural auxin found in plants that is responsible for natural root stimulation. Most rooting products do not contain IAA, but rather a synthetic form of indolebutyric acid (IBA) and/or naphthaleneacetic acid (NAA). These rooting hormone products can come in different forms, including powder, liquid, or gel.
Organic Root Stimulator - Willow Extract
There are many organic cannabis growers who struggle with the cloning stage because they don’t want to use synthetic hormones. Willow extract is probably the best natural, organic rooting stimulator available. The reason willow is so effective is because it contains two auxin hormones: salicylic acid (SA) and IBA.
After dipping the cutting in a rooting hormone, it can be placed into the grower’s preferred medium. Stone wool, coco fiber, peat moss, perlite, and clay pebbles are all examples of inert media cannabis gardeners commonly use for clones. Some growers choose to place the freshly cut clones into a light soil mix for rooting. As long as the medium has the ability to hold some moisture and provide oxygen to the developing roots, it can be effective for cloning.
As stated earlier, consistent atmospheric conditions are the foundation of cloning success. For clones, a temperature range of 70-80˚F is fine. If it is not possible to maintain this temperature range consistently in the grow room, it may be necessary to create a small sub-climate elsewhere. A seedling heat mat is a great tool to help maintain the proper temperature during the cloning process.
Humidity is also a contributing factor to successful cloning. Many cannabis varieties root fastest in a high humidity (80-99%) environment during the first few days. Humidity domes or chambers are tools a grower can use to maintain a higher level of humidity during early cloning. It is a good idea to acclimate the clones to the ambient humidity after three to seven days. This can be done by removing the humidity dome each day for a few minutes, then increasing the duration of removal each day.
CO2 for Cloning
Time is always of the essence and cloning cannabis is no exception. The faster a grower can get his or her clones rooted, the faster the plants can be moved to the next stage of growth. Unfortunately, the ideal environment for cloning (warm temperatures and high humidity) is also conducive to pathogenic fungi and bacteria. Therefore, the faster clones can be rooted and moved to the next stage, the lower the chance of pathogenic organisms taking hold. One method used to boost the rate of rooting is to supplement CO2 to the cloning area. Increased CO2 levels in the cloning stage has many benefits, including faster rooting, reduced transpiration, and a reduced likelihood of pathogens.
When a clone’s leaves have access to enriched CO2 levels, the chemical equation known as photosynthesis can occur more quickly. The clones can absorb CO2 through their leaves and, with the addition of water and light energy, create sugars. Sugars are an important fuel which provide clones with the energy they need for making roots. In other words, raising the CO2 levels in the cloning area increases the speed at which these valuable sugars can be produced. The faster clones can develop roots, the higher the overall success rate.
One of the main reasons cuttings are kept in a high humidity environment is because, without a root system, the cutting’s leaves become the main source of water control and retention. Plants absorb carbon dioxide through the stomata on their leaves. When the stomata are open, the plant can absorb CO2. Transpiration also occurs when the stomata are open. When a cannabis horticulturist enriches his or her cloning environment with CO2, the plant can absorb more CO2, in turn, limiting water loss through transpiration.
Reduced Likelihood of Pathogens
Enriching a cloning area with CO2 is one of the most effective and safest ways a grower can reduce the likelihood of pathogens attacking the otherwise susceptible cuttings. It is believed CO2 is an effective anti-fungal due to its ability to alter intracellular pH levels. In other words, an enriched CO2 environment during the cloning stage can change the pH of the leaf’s surface, making it impossible for certain fungi to become established.
Methods of Administering CO2 to Clones
CO2 burners, compressed CO2 tanks, or mycelium bags can all be rigged up to increase CO2 levels during the cloning stage. However, too much of a good thing can be bad. For clones, CO2 levels between 1,000-1,300 ppm should be the absolute maximum. The CO2 pads specifically designed for cloning chambers are perhaps the best way to enrich a small cloning chamber with CO2. These pads are activated by the humidity within the dome (or when the clones are misted with water). CO2 pads specifically designed for cloning usually place the CO2 levels between 450-1,200 ppm. This level of CO2 is ideal for cloning because there is enough to boost photosynthesis (creation of sugars) and prevent certain pathogens from establishing, but not so much that root growth will be inhibited by displaced oxygen.
Cannabis growers who master the art of cloning are poised to be more successful growers. Atmospheric conditions, the selection of a mother plant, and the rooting hormone and medium used will all play significant roles in a cannabis grower’s success or failure in cloning. Ideally, a cannabis grower should be able to consistently have a 90% or higher success rate with his or her clones. Growers who do not achieve that mark should closely examine their cloning procedures to see where they can improve. Cannabis growers who consistently produce healthy clones will have the next generation of plants ready to go and reap all the benefits that come with an uninterrupted perpetual garden.