A clone is a section of branch that gets cut off a mother plant and rooted, transforming it into a new plant. It’s called a clone because it is genetically identical to the mother.
Because clones are genetically identical to their mother plant they will all grow the same way. For example, their rate of growth, node spacing, and leaf shape will be the same.
A primary benefit of genetically identical plants is when they are grown together in a group their heights all stay the same, making it easier to light their canopy. When plants all grow at different rates, shorter sections of the canopy receive less light than the taller sections, resulting in underdeveloped buds on the parts of the canopy that don’t get enough light.
Clones also allow you to grow only the very best plants. Plants grown from seed are compared for positive attributes such as yield size and quality through a process called phenotyping. The best plants are chosen as mothers and their genetically identical children become production plants.
Cuttings are especially vulnerable to bacteria, mold and viruses. A clean work environment and tools helps to prevent contaminations. Before taking cuttings, scrub down the entire work space with paper towels soaked in a solution of 10% bleach and 90% water. Disinfect scissors by wiping the ends with paper towels dipped in isopropyl alcohol. Wear a clean pair of plastic gloves while you are cleaning and while you are taking cuttings.
Fill a freshly washed jug with clean water for temporarily holding cuttings during the process of extracting clones. Extracted clones can be held in a jug, just like fresh cut flowers in a vase. This prevents the ends from drying out during the extraction process.
Prepare for a cloning session by adding some root stimulant powder to a freshly washed small glass for dipping the stems of cuttings in.
Root stimulant powder is a commercially available product that contains chemicals that stimulate new roots to begin growing from a severed stem.
Never dip clones directly into the bulk supply container of root stimulant because the entire container could get contaminated. For same reason, after a cloning session don’t put unused power back into the bulk supply container. Throw it out.
Clones will have trouble rooting if pH is not within a specific range. Rockwool does not natively have the right pH balance and needs to be prepared in advanced by soaking it in dechlorinated and pH balanced water.
To prepare Rockwool, pH balance water to 5.5 using pH up and pH down solutions. pH up and down are very concentrated. A 3 ml dispensing syringe makes it easier to dispense it one drop at a time.
Dechlorinate water using a water filter or with Vitamin C (ascorbic acid).
After the water’s pH is adjusted to 5.5, soak rockwool cubes in it overnight. This will correct the pH of the rock wool.
Rockwool is made up of spun glass fibres that are not healthy to breath in. Use a dust mask when handling dry rockwool because the fibres can become airborne. Rockwool is safer to handle when it is wet.
Preparing Net Pots
Nest rockwool cubes inside 4” net pots filled with hydroton.
Rockwool cubes are slightly over saturated after soaking in solution overnight. Oversaturated cubes run a risk of rotting plant stems when they are inserted in the rockwool. After soaking, give rock wool cubes a light squeeze to eliminate a small amount of excess water before adding them to the net pots.
Removing Clones From Mother Plant
To take a clone, remove the top part of a branch by cutting just below a node. The cutting should have 3 nodes plus the top canopy.
Trim all the shoots and leaves off the stem of the clone. Leave only the top growth intact.
Stripping away the bark around the bottom node to expose the underlying tissue promotes more robust root growth.
Setting Cuttings In Net Pots
Dip the bottoms of the clones in the shot glass containing the root stimulation powder.
Push the plant stem into the rockwool cube after coating the ends with root stimulation powder.
Trim the leaf tips of the cuttings. If you don’t, the leaves tend to become rotten or mouldy during the rooting process. Trimming the ends also reduces the transpiration function of the clone, leaving it with more energy for growing new roots.
Cuttings are rooted and become clones inside a humidity dome. A humidity is like a life support system for your clones because it provides an environment with high humidity and temperature. Outside of the humidity dome, cuttings can die because they have no roots to draw up water. Inside the humidity dome, high humidity levels allows them to absorb water through their stem and leaves.
Clones root fastest with temperatures between 24° – 30°C (75 – 85°F), with the ideal temperature around 25°C (78°F). A large heat mat kept under the clone dome helps raise its temperature. If the heat mat is too powerful and the humidity dome gets too warm, set an electricity timer to switch the heat mat on and off automatically until the correct temperature is reached, or place a towel over the heat mat to dull the heat. Temperature is an important detail because the faster clones root, the higher their survival rate is.
To set up the humidity dome and net pots, add enough water to the bottom of the humidity dome so that the hydroton in the net pots is submerged in the water, but the rockwool cube is above the water line. The hydroton can draw water up using its wicking action to maintain the rockwool, keeping it moist.
Adding a bed of loose hydroton to the bottom of the humidity dome will help anchor the net pots in place and reduce light exposure to the clone’s roots once they emerge from the net pots.
The humidity dome should be kept as clean as possible to prevent fungi build up. Clones are very vulnerable to harm resulting from an unsanitary condition. Every week, empty all the water from the humidity dome and replace with fresh water. Changing over the water also has an affect of oxygenating the water which is beneficial for the clones.
Water & Nutrients For Clones
For the first week, the water in the humidity dome doesn’t need any nutrients. pH balance the water to 5.5, dechlorinate it, and add sodium benzonate at a concentration of .13 gram / 100 litres to prevent fungi infections.
After the first week, prepare the water as above, and also add vegetative growth fertilizer at the following concentration:
Clone & Seedling:
350 – 500 TDS
0.7 – 1 EC
Foliar sprays are very beneficial for clones. Apply a foliar spray up to 3 times per day, spraying the canopy of the clones while avoiding drenching the rockwool cube. Clones can draw water and nutrients through their foliage and this is very helpful for them before their new roots have grown in.
Prepare a foliar spray with 5 parts humic acid to 2 parts kelp.
Lighting For Clones
Maintain light levels for 24 hours per day for the full rooting period.
Use a full spectrum light with emphasis on blue wavelengths, 400 nm – 500 nm. Blue light discourages stem elongation and encourages root growth.
5,000 – 7,000 LUX