Plant Cloning Explained
Cloning has been around for centuries. Cloning allows the gardener to replicate a genetically identical plant from a parent plant. The clone will have the exact same characteristics as the mother plant, the same growth habit, disease resistance, fruit shape, flower color and yield potential.
The materials that are required for taking cuttings are:
Taking a cutting
- Select a branch or stem that has at least 2 or 3 sets of leaves.
- Locate a spot on the branch between, or next to, a set of leaf nodes where your cut will be made (leaf nodes are where the branches/leaves come out of the stem). Leave at least two sets of nodes above the cut. Use a pair of scissors to take the cutting off the mother plant. Cut away the largest leaves first as it is difficult for a cutting to maintain these large leaves without roots.
- Remove the lower 1 or 2 sets of branches (stems and leaves), leaving two upper sets of leaves. Place the cutting on a tile or cutting board and use a sharp razor to make a clean, neat, 45 degree slice. It is important that you do not damage the branch while handling. Do not use scissors to make the 45° cut as scissors have a crushing action when it cuts. A crushed or bruised stem will have a reduced chance of rooting. Difficult to root plants may require ¼” of the stem to be scraped, with the blade, above the cut. This wounding helps rooting by disrupting the cells on the surface of the stem. Another practice is to cut a notch ¼” above the 45° cut. Your cutting should now be 2-4” tall with two leaves at the top.
- To prevent an air bubble (embolism) from lodging in the stem where the cut is, immediately dip the base of the cutting into a quality cloning gel, like Olivia’s, Clonex or RooTech. Follow the directions for these products; if you leave the cutting for too long in the gel it can “burn” the cut area. Wipe off the excess rooting gel for extremely sensitive plants.
- Place the cutting into your growing medium. Place the cutting at least ½” deep into the rooting medium.
Factors which influence success
- Parent Stock - The condition of the parent plant is an extremely important factor to consider when taking cuttings from a particular plant. If the mother plant is infested with insect pests, root rot and/or mold she will be stressed, and thus the quality of the cuttings will be poor. The insect pests and disease will be transferred to your garden creating more problems later on. Never select a plant to be a mother if it is lacking in vigor. Cuttings from these plants will always produce bad clones, slow rooters, susceptible to disease and lower yielding. Always select parent stock that has the best disease resistance, pest resistance, most vigorous, most suitable growth habit and of course the highest yielding. Avoid taking more than 30% off the mother plant as cuttings; this will stress the plant too much and will retard the vegetative growth for future cuttings. Always replace the mother plant every year. The reason for this is that cuttings taken from a younger plant root easier than cuttings taken from plants that are a few years old. If a gardener has a favorite plant that they want to clone that is a few years old then take the cutting from a shoot that is at the base of the plant. These shoots are called juveniles and will root easier than cuttings taken from higher on the plant. The mother plant should always be kept in the vegetative state. To help the mother plant produce lush green foliage use kelp (e.g. Maxicrop or Seaweed Extract) as a spray on the leaves (follow the manufacturers directions).
- Rooting Medium - There are many types of rooting mediums that are available to the gardener. The ones that we are focusing on are: rockwool cubes, Rapid Rooter plugs, Oasis cubes and aeroponic cloning systems. For aeroponic cloning systems (e.g. EZ Clone, Power Cloner and Clone Machine), see “Water Quality”. Rockwool cubes need to be pre-soaked at a pH of 5 prior to placing the cuttings into them (or use Rockwool Soak). Keep the cubes moist but not saturated with water. Once you pour the water onto the cubes and have allowed the excess to drain off, gently squeeze each cube thus making it release more water. If the cutting stays too moist it will have a higher chance of rotting. Rapid Rooters and Oasis cubes are ideal products to clone in as both of these mediums hold less water and allow more oxygen in than the rockwool cubes. Also, neither medium needs to be pre-soaked before being used. The Rapid Rooter plugs also have Trichoderma which is an aggressive fungi that feeds off of other fungi, especially the bad root/stem rot causing fungi.
- Rooting Hormone - For plants that are easy rooting, RooTech or Olivia’s cloning gel is the choice to use. For cuttings that are more difficult to root (such as hardwood cuttings) then Clonex should be used.
- Water Quality - Water quality is often over looked in the cloning process. Here in California we have had great success with using Arrowhead Mountain Spring water (as opposed to Arrowhead Drinking water) for cuttings. The spring water has just enough minerals for the cuttings during the rooting process without being toxic to the young cutting. Tap water may contain large numbers of impurities, chloride and sodium, all of which can slow down the rooting process and even damage the tender cutting. A mix of RO (reverse osmosis) water and tap water can be used as long as the ppm is within 50 - 150. Make sure that the water is pH balanced between 6 - 6.3. Always add 15ml of HydroGuard per gallon of water; this will keep the cut healthy and free from rot causing fungi.
- Temperature - The ideal temperature range for cuttings is 72°F - 80°F. It is always better to have the root zone temperature at 76°F - 80°F while the canopy is kept at 72°F - 80°F. The warmer rooting zone helps produce roots quicker, while the cooler canopy minimizes transpiration from the leaves. If the rooting zone is too cold, especially during the winter months, then the cloning system should be placed on a heating mat that has a thermostat control set to 80°F. In winter, when the water temperatures in the pipes are cold, take care to allow the water to reach room temperature before adding it to the cloning system. Cold water on the cuttings or young roots will shock the clones and retard their rooting abilities. For the summer months keep the water temperatures below 83°F; failure to do this will cause the cuttings to rot. The higher water temperature increases the growth rate of root rot pathogens. Warmer water also holds less dissolved oxygen which is needed by the cutting. Lower dissolved oxygen always favors root rot organisms. If you notice that your cuttings are becoming slimy and soft make sure that these cuttings are removed immediately. This rot will spread to the other cuttings very quickly.
- Humidity - Having the correct humidity is important for successful cloning. The ideal humidity range is between 70-80%. Low humidity will cause the young cutting to transpire and loose more moisture than what it can absorb - this kills cuttings. If the gardener is unable to maintain adequate humidity levels by the use of a humidity dome or misting then Vita Grow Anti-Wilt Concentrate should be applied to the cutting. This product creates a moisture barrier thus minimizing moisture loss by transpiration. If the humidity level is too high the cuttings can be attacked by fungi on the stem, leaves and the growing point. Gardeners who mist their cuttings should add Serenade at a rate of 2 teaspoons per quart to the misting bottle; this will help keep fungi from developing on the cuttings. Gardeners should also make use of a humidity gauge; there is no room for guessing when it comes to cloning.
- Light - Selecting the correct lighting is important to the cutting. The best type of light to use is fluorescent. Fluorescent light has the correct balance of blue and red spectrum and is also a soft light. The softer, less stressing source of light is important to the cutting in the early stages of life when stress is high due to being cut away from the mother plant and no roots have yet formed. The best fluorescent lighting system to use for cloning is a T5 Fluorescent system. T5’s have the highest light output and come in various sizes - single bulb in a humidity dome for one tray, 2 foot 2-bulb, 2 foot 4-bulb, 4 foot 2-bulb, 4 foot 4-bulb, 4 foot 6-bulb and 4 foot 8-bulb. Gardeners who use a T5 lighting system also have the choice of mixing Daylight (blue) and Warm (red) bulbs. The compact fluorescent bulbs would be the next best choice and are available in 105W through 200W. The most common lighting pattern for clones is either 18 hours or 24 hours of light. Using the 18 hour light pattern allows the plants a 6 hour period of darkness; this is when the plant converts its sugars into starch. This starch is then stored in the roots. Providing a dark period will help a healthier root system to develop. If possible avoid using HID lamps as a cloning light; these lights are too intense and produce too much heat (increasing the transpiration rate) for cuttings. If you are covering a large area and would like to use an HID lighting system, try to use a metal halide lighting system and keep it a few feet above the plants. Once the cuttings have rooted you can lower the light to its normal height.
- CO2 - Providing cuttings with CO2 is an often overlooked practice.CO2 is one of the vital components that is required for a cutting to develop a healthy root system. CO2 is required by the leaves and not the cut nor the young developing roots; adding CO2 to the root zone will kill cuttings. The cutting absorbs CO2 through the leaves and converts it, along with water, into sugars. These sugars are important in providing the cutting with the necessary energy to form roots. Supplying the cutting with 1000 - 1500ppm CO2 makes this process faster and more efficient. The clone will have a healthier and better root system to begin its new life with.
- Aeration - Providing the clone’s newly developing roots with dissolved oxygen is just as important as providing the leaves with CO2. Roots need to breathe oxygen; a lack of dissolved oxygen will slow and even stop the root growth. Lack of dissolved oxygen will cause roots to rot, killing the clone. The best way to give clones dissolved oxygen is to oxygenate the water before giving it to the cutting or rooted clone. Put a couple of air stones into a bucket of water and let it bubble for a few hours; this also has the benefit of allowing the water to warm to room temperature. For those who use cloning machines, put the air pump outside the growing area where the CO2 level is lower and the atmospheric oxygen level is higher.
How to look after your cuttings
- Once all of the cuttings have been taken, mist with a fine spray (add Serenade to mist bottle) and place a humidity dome over the cuttings. Once the cuttings have been placed into the rooting area they will normally wilt. The leaves will collapse and “hit the deck”. After 24 hours the cuttings should be standing erect and the leaves pointing to the light. This is a good sign, the cuttings that don’t stand after 24 hours can be discarded. Be strict with this because weak stragglers are not wanted. Cuttings that don’t stand erect after 24 hours also can allow harmful organisms to gain a footing in the cloning system.
- Lift the humidity dome off at least twice a day and mist leaves. Lifting the dome also allows the clones to get fresh air. Keep rooting medium warm with a heat mat and thermostat controller. Make sure rooting medium is moist.
- After a few days you may notice that some of the leaves are beginning to turn yellow; this is a natural process (however this doesn’t always occur). It also tells the gardener that rooting is about to begin. The yellowing will disappear once the roots have formed and are being fed a light nutrient solution.
- After 5 - 7 days tug at a few cuttings, if the cutting comes straight out inspect it more closely. If the cut has become soft and slimy, toss it out along with its rooting medium. If the cut isn’t soft and slimy but has white bumps just above the cut then it is about to root. This is the time when Rhizotonic should be added at a rate of 15 ml per gallon of water. This gets the root system kick started and helps produce lush healthy white roots (it’s an amazing product). If you find a cutting that does not come out of its medium, it has rooted - do not tug it out! For those with cloning systems this process is much easier. Discard all cuttings that are beginning to rot; harmful organisms will spread easier in the machines. Add HydroGuard to the cloning system reservoir at a rate of 15ml per gallon of water. Most gardeners will also add Power Clone, Clonex Clone Solution, or Olivia’s Cloning solution to the reservoir to help the cuttings produce roots.
- Once the cutting has rooted introduce it to a ¼ strength nutrient solution (whatever brand you prefer). Remember, more is not always better. Keep the pH at around 6.0.
- Once a strong rooting system has been established (1½ - 2” long roots in the clone machines) the clone is ready to be transplanted.
- Use SuperThrive to help your clones overcome transplanting stress, a few drops per gallon of water is all that is needed. Thrive Alive Red is also a good product to use for this purpose.
- Power Cloner by American Agritech - The latest innovation in cloning machines comes from American Agritech/Botanicare. This is a good all in one cloning machine. It comes with the pump, sprayers, neoprene plugs and an air pump. One of the great features about this machine is that it comes with a humidity dome. This unit also comes with a sample of Power Clone Solution and HydroGuard. The Power Cloner is available in 45, 70 and 165 sites.
- EZ Clone by EZ Clone - This cloning machine has been on the market for a few years and is very popular. Recent changes to the manifold and a pump change to the Mag Drive pump has made this machine one of the most effective cloning machines around. The machine comes in three sizes - 30, 60 and 120 sites
- Clone Machine by American Agritech - This machine uses sprayers but also makes use of net pots, Hydroton rocks and Root Guards. This machine is useful to those gardeners who have aeroponic systems, bubbler buckets or grow in Hydroton rocks. Once the cuttings have rooted in this machine it is easy to transplant the clone into the main garden without disturbing the root system. This unit also comes with a sample of Power Clone Solution and HydroGuard. The Clone Machine is available in 8, 20, 42, 64 and 141 sites.
Always make sure that after every batch of clones that the clone machine is disinfected with 300 ppm strength of hydrogen peroxide 10% (1 teaspoon per gallon of water if using Oxy Blast!). Make sure no plants are in the system when this is done.
Cuttings are never guaranteed to have a 100% rooting success; all the gardener can do is help increase the chance of rooting.
take 10% off any of the products mentioned in this article with
coupon code: holly (good during December 2005 only)
© 2005 Bettergrow Hydro, Inc. All rights reserved.