Cloning is a way of propagating plants through asexual reproduction of the plant by cutting and rooting a healthy shoot. This creates clones. It is also known as ‘taking a cutting’. Your marijuana cutting requires four things in order to root:
- Low light to stimulate rooting. As the clone will not be adding leaf mass or performing significant photosynthesis, more is not better. The light basically triggers certain hormones
- A support structure
- Moisture around the roots
- High humidity to keep the leaves from drying out.
The simplest way for a single clone is to put your cutting in several inches of water in a Dixie cup and cover with a plastic baggie to retain moisture. Change the water every 3 days. Marijuana clones will root in roughly 6 to 14 days. Just prior to the appearance of the roots, white bumps will be visible on the lower part of the stem submerged in water (if that is the method you are using). Some gardeners transplant when the roots are 1” long while others wait until they are 6” long. Personally we like to wait until they are at least 3” long. Longer roots take more time, but generally results in less shock when transplanted.
When it comes to rooting mediums, there are three predominant schools of thought:
Use rockwool cubes or a non-soil equivalent. Rockwell provides a great environment for clone rooting due to its terrific airflow and moisture retention. You can find these cubes at most any grow store or online.
Transport your clone into soil. When using soil, don’t choose one with an abundance of nutrients, and make sure you don’t over or underwater your soil when attempting to root your clones.
Root in water. Water cloning requires no use of rooting hormones or mediums. You just drop your cutting in water and keep it there until roots and new growth begin to develop.
Rooting cannabis clones with a gel or powder
Although it is possible to root cuttings in water it is recommended that you use a rooting gel or powder. Remove the bottom leaves from the cutting and dip it in the rooting compound, then plant the cutting in your desired growing medium. Rockwool cubes work particularly well.
Every grower has his or her own ideas about nutrient programs for cuttings and young clones or seedlings. Giving new cuts any nutrients would be pointless until roots develop as they cannot absorb any mineral content. It could also further the initial shock these poor little branches are going through.
Instead, these new cuts should be dipped in a rooting hormone (gel or powder-based) before being placed into their plugs for rooting. Sometimes it is helpful to create a mild solution of distilled water and vitamin B1 and apply to the plugs to help alleviate any stress the younglings are going through and assist in the rooting process.
Once roots have begun to appear on the underside of their Rockwool plugs or peat pellets, they can start to handle mild nutrient solutions—very mild.
It is important to understand that nitrogen (N) can work against the plant hormones or rooting hormones that may have been applied during the cutting. Salts in nutrients also make it a lot harder for young developing roots to absorb the water they need. Once you see the white tips of roots protruding from your plugs, your plants are in good shape and much more likely to survive and grow into mature adult plants.
During the vegetative phase, we use “grow” formulas that are rich in nitrogen. However, nitrogen tends to divert growth from the root zone to the plant’s top. This is not ideal as it is critical to the life and development of the plants to have a large, robust root structure. Thus, you would not want to use a “grow” formula early on, but rather a mild nutrient solution of very low nitrogen. Looking at the N-P-K (nitrogen-phosphorous-potassium) ratio on the labels of nutrient bottles will help you. Something like a 1-3-3 ratio would be ideal.
If you are unsure about mixing nutrient solutions or are worried that your solution might be too strong for young plants, you can test your solution by measuring its pH level using a pH meter or pH (litmus) strips. For young clones and seedlings still developing their roots, the pH range required for rooting cells to have maximum nutrient absorption should be between pH 5.1 – 5.7.
Once your plants have been transplanted into the larger containers for their vegetative growth stage, wait a week for them to settle in and get accustomed to their new environment before starting with their “grow” nutrient program.