An interesting property of the cannabis plant is its ability to be "cloned." Cloning marijuana is the asexual (male plant pollination not needed) propagation of the plant by clipping a branch tip of a female plant and rooting it.
A key benefit of cloning cannabis is it cuts the time for a plant to mature. Indoor growers will commonly establish a smaller vegatative/cloning room separate from the larger flowering room.
The process of cloning marijuana begins with a mother plant.
As the name implies, the mother plant is a female plant. Ideally the plant is older than 2 months old. Cloning cannabis plants with a mother plant younger than 2 months will often result in slow, uneven growth.
A clone is an exact genetic replica of the mother plant which means the female plant will produce 100% female plants all exactly like the mother. When cloning marijuana in a very controlled environment the plants will look virtually identical to the mother.
For best results, start new others from seed. Give the mother plants 18-24 hours of light per day to induce fast growth. Reduce your nitrogen by 10% to promote rooting in clones.
Preparing To Clone
Cloning marijuana is the most traumatic experience for a plant. A stem that grows upward and produces branches and leaves is suddenly forced to grow roots. The plant's entire chemistry changes.
Reducing nitrogen intake and increasing carbohydrate intake will help cloning marijuana plants to quickly develop a dense system of roots. You can elevate levels of carbohydrates by flushing the plant growing medium with water to flush the nutrients. Be sure to use a medium that can withstand heavy flushing and not get waterlogged.
Carbohydrates and hormonal content is highest in the lower, older, more mature branches of the mother plant. A rigid branch that folds over quickly when bent is a good sign of high carbohydrate content. When cloning marijuana plants try to use branches near the base of the plant's main stem. This is the oldest part of the plant but where the newest root hormones are located. The top of the plant contain older hormones so cuttings from this area root slower and should be avoided.
Here are the basics you will need for cloning marijuana. Keep these items within arm's reach and disinfect your tools and working surfaces with alcohol, vinegar or a 5% to 10% bleach solution.
Tools For Cloning Marijuana
- Sharp scissor or razor blade
- Rooting cubes like rockwool
- Small cup with clean water
- Hormone solution (read directions beforehand as some premixing may be required)
You can place cloned plants in soil for propagation, however for a higher success rate and more consistent results, grow cubes are the recommended choice.
Prepping Your Grow Cubes
Fill the bottom of a sturdy plastic tray for holding your grow cubes with coarse washed sand, vermiculite, soilless mix or fine potting soil. Saturate the substrate with water. Poke a small hole in the bottom of the grow cubes slightly larger than the stem and rest about a half inch from the bottom of the plastic tray to allow roots to emerge.
Making The First Cut
When cloning cannabis, select a mother plant that is at least 2 months old. Any younger than that and growth can be uneven and slow. With a sharp, clean blade, make a 45 degree cut across a firm, healthy branch close to the base stem of the mother plant. Trim off the lower leaves and growth nodes so the stem can fit into the grow cube. There should be at least 2 sets of leaves above the grow medium. Immediately
place the cut stems in the cup of water until ready to apply hormone solution.
Once you've taken all the cuttings you need, take the stem of your cutting and swirl the tip of the cutting for about 5 to 15 seconds in the hormone solution. Once you've swirled your first cutting, place the stem in your grow cube.
Gently pack the rooting cube material around the stem. Take special care to keep a layer of the hormone gel, powder or solution (depending on your choice) around the stem when packing the grow medium around the stem.
Once all your cuttings have been planted in the grow cubes, mist the plants lightly until the surface is evenly moist and continue to keep moist at all times.
Remember, clones do not have roots to bring moisture to the leaves yet. Until roots are established, moisture is absorbed through the leaves so it is critical to keep leaves moist and keep the grow medium evenly moist but not soggy.
18-24 Hours of Light
Clones will root fastest with 18-24 hours of fluorescent light. If an HID (high intensity discharge)
light is used, place the plants on the perimeter of the garden area so they are not subject to such intense light (but be sure to rotate for even exposure if necessary) or shade them with a cloth or screen. A 400-watt metal halide 4-6 feet away should be the right amount of light for clones to take root.
If an LED (light emitting diode) lighting system is used, full spectrum LEDs are a great way to provide clones with warm and cool light with minimal worry of burning plants, overheating grow rooms and running lights for 24 hours. Additionally, LEDs use a fraction the power consumption of HIDs.
When cloning marijuana, humidity levels of 95-100% the first two days will help roots to develop. After the first two days the humidity level can be gradually reduced to 80-85% over the following weeks. A simple humidity tent can be made from plastic bags, rigid plastic or glass. Remember to ventilate with small openings to allow air flow and the clones can breathe. Cut leaves in half to lower the transpiration surface and avoid overlap. Overlapping can foster fungus growth. Continue to keep the grow medium evenly moist.
Your little clones will root faster if the grow medium is slightly warmer than the ambient air. A warmer substrate will increase the underground chemical activity. For best results, keep the rooting medium at 70-80 degrees Fahrenheit (24-27 degrees Celsius). Anything above 85 Fahrenheit/29 Celsius can cause damage. The combination of warmer grow medium and cooler ambient temperature slows disease and retains moisture. Put clones in a warm place and use a heating pad, incandescent light or heating cables to keep your grow medium warm. But remain vigilant monitoring temperatures and not burning down the house.
Growing Marijuana Tip: If you'd like an easy to read compendium of everything you need to know about growing quality marijuana, check out "Growing Marijuana" by Ryan Riley. Ryan provides wisdom from over 20 years of medical marijuana cultivation.
When cloning marijuana, some cuttings may wilt but should regain rigidity in a few days. Clones should look close to normal by the end of the week. After a week, cull any remaining wilted cuttings or put back under the humidity chamber to grow more roots. Within one to three weeks, your cloned marijuana plants should have roots. Some signs of rooting include yellow leaf tips, roots growing out of the drain hole of the grow cubes and vertical growth of your cloned plants.
The stems of cloned marijuana plants will develop stubby, callused roots called primordia. Primordia will look semi-transparent to white and should look healthy. Once this root and transport system is established, the cloned marijuana plant is ready for growth.
Once your clones have taken root, they can handle increased levels of light. Fertilization with a mild solution can also commence once the cloned marijuana plants start their vegetative growth stage.
Transplant your strongest, well rooted clones when your plants become too large for their container.
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