A clone, also known as a clipping or baby, is simply a branch cut from a plant. These branches are cut, dipped in a rooting solution and placed into a simple growing medium.
For clones to properly root and survive, we need to create a low VPD environment that will protect them from high transpiration rates. Temperatures in a cloning environment should be between 70-78F with relative humidity between 75-90%.
Clones can be taken at just about any stage of the plant’s development – even during flowering (see Monster Cropping). Ideally, a clone is taken from a plant during the vegetative stage of growth. If a clone is taken after the plant has gone into flowering, it will undergo a re-vegetative stage that can take weeks or even months. The further the plant goes into the flowering cycle, the longer it can take for the clone to recover and revert back.
Clones can be taken of any size. If you take a cutting that’s too large, it will be difficult to work with and fit inside a standard tray and dome. If you take a clone that’s too small, the clipping will be fragile and can take longer to begin rooting and growing.
The first step in cloning is identifying a suitable branch to cut. You are looking for something that is not too small, not too big, and as straight up and down as possible. Branches that are curling or bending for light can take up unneeded space inside of a crammed propagation tray. The more vertical the specimen is, the easier the whole process will be.
Now that we have a good-looking branch spotted on the plant, take a clean razor blade and cut the stem at a 45-degree angle. Remove any smaller unnecessary growth on the new clone with the razor and use a clean pair of scissors to reduce the size of any larger leaves. Thoroughly wash your hands or use rubber gloves and try to keep exposed cuts away from any dirty surfaces.
ProTip: Freshly cut clones can be kept happy and healthy by placing the cut stem in a cup of water. Clones can be kept alive this way for hours while more cuts are being taken.
After you have all the clones you need, dip the newly cut portion of the branch into a liquid rooting hormone of your choice. From there, you will firmly push the clone into the new growing block or medium you chose. You need to make sure the new clone is seated firmly in the block (not too shallow and not too deep). Cloning is a skill and some patience and practice will help you get it mastered. It’s always a good idea to cut a few more clones than you’ll need until you get more comfortable with the entire process.
Once the clones have been firmly seated into their new medium, they are placed into a propagation tray. A 2 tray system is a must-have and allows for proper drainage away from the blocks and a water storage area for keeping the relative humidity up. Above the top tray is a clear plastic dome that traps humidity and heat in the environment while the clones begin to root.
After the clones are taken and the tray is filled, a clean spray bottle with water is used to lightly mist the new clones, the inside of the plastic dome, and the plastic tray itself. You want the growing cubes/medium to be moist but not over-saturated or poorly drained. For the first 48 hours of the clones’ life, you will completely close all of the vents, trapping any humidity inside the dome.
The next step is to set up your warming mats and slide them under your trays. Heat mats are used to increase the temperature and humidity inside of the dome. Heat mats can also create a lot of problems – they can easily get too warm for clones and precautions should be taken. Placing a towel between the heating mat and the bottom of the tray will help dissipate the heat inside of the tray. Another good method is hooking the heat mats to a timer. Have them turn on and off every 5-15 minutes. Use a temperature and humidity monitor with a probe inside of the dome to dial in the proper levels of 75-80F and 70-80% RH. You will want to visually see some condensation on the sides of the dome. Leave the new clones alone and re-check the temperature and humidity levels every 2-12 hours for any potential issues that may arise.
Now that the environment is dialed, we need to set up the lighting. A low wattage fixture (fluorescent is common) is ideal and should be set 12-24” above the plastic dome. Continue to keep a close eye on the temperature and humidity levels in the dome. Mist the plants and the inside of the dome if things have dried out. Make sure that the humidity inside is still between 70-80% RH. If the humidity or temperature gets too high, temporarily open the dome and find a solution to the problem. If your humidity is too low, continue to mist the inside of the dome and add a little water to the bottom of the second tray. If the humidity is too high, slightly crack the vents and allow the cloning environment to breathe.
After 5-10 days, the rooting process should start getting underway. Once a majority of the plants have begun rooting, they are ready for a cloning solution. You will want to hydrate your clones with a flood and drain style approach. Once roots begin to show, fill the lower tray with a cloning solution. Let the upper tray soak in it and saturate the blocks for 2-3 minutes. Drain and pour all of the excess nutrient solution out of the lower tray and into a 5-gallon bucket. Cover the bucket with a lid and reuse this solution as necessary over the next week.