One of the most common frustration we find with our customers is on the subject of cloning. Growers that have been taking clones for years will occasionally fall into a bad habit, and not know why their success rates have plummeted. This blog post will point out some of the most common mistakes made in the cloning room and how to avoid them for future cloning success.
Healthy Plant Stock
The first step in getting healthy clones is to start with a healthy stock plant (the plant you will cut from). Your plant should have strong genes, should be free of pests or diseases, and should not be displaying any symptoms of deficiencies or stress. This plant should also be large enough to support cutting from. If the plant is a fresh seedling, give it time to develop so that there’s healthy side branches to cut from. Generally speaking, the best time to take a cutting is when the plants are actively growing. Sometimes we are forced to take a cutting while a plant is flowering, and this can work, but be prepared for it to take a little longer.
***Grower tip – Spray your stock plants with seaweed and fulvic acid a few days before taking cuttings. This will prime the plant to hold on to nutrients longer, giving the cutting a better chance to survive in the fragile rooting environment.
Ensure Proper Moisture
Many growers make the common mistake of keeping their media too wet. Moisture and humidity are key in cloning, but wet is not good. Wet media lowers the oxygen levels in the media, which usually leads to rotting stems. Two of the most common medias used in cloning are rockwool and starter plugs. Rockwool is preferred for hydroponics, but could be used in soil. Starter plugs can be used in both. I personally lean towards starter plugs because of their ability to hold moisture, yet breathe. Rockwool is dry when purchased and will need to be soaked in a slightly acidic water solution (5.5 pH is ideal). After soaking, some of the water will need to be gently squeezed out of the media. This will pull more air into the media, giving a better water/air ratio. The same can be done with the starter plugs, but these will come pre-moistened almost to the proper levels. I give my plugs 2 or 3 squirts of water directly to the top before I place my cuttings. The media should be evenly moist, but not dripping with water. Remember, oxygen is key! The media should never be sitting in water (commonly asked question). Grodan makes an insert call the Gro-Smart Tray that elevates the rockwool off of the bottom of your flat tray, allowing you to fill the bottom of the tray with water, without the rockwool sitting in it.
Keep it clean!
Be sure to start with clean equipment. Some growers prefer to buy new domes and trays every time they clone, but these products can be cleaned and sterilized by using a 15% bleach solution or food grade hydrogen peroxide. For easy-to-wipe surfaces, use 3% hydrogen peroxide. A stronger concentration will be needed for water cloners that contain hard to reach surfaces inside pumps and manifolds (34%). These practices are especially important if you are using hydroponic cloners like the EZ-Clone or Super Sprouter AquaClone. Infection of bacteria is probably the number one cause of failure in these systems.
The last paragraph segues perfectly into this one because higher temps bring on more bacteria. It is critical to have full control over your grow room temperatures if you want to remain successful with cuttings year round. Problems often occur in the summer when grow room temps are 80 degrees or above. The ideal temperature for a space is around 75 degrees, and humidity should be in the 60 to 80% level. We highly encourage heat mats during the winter, but be careful not to bake your clones. Give some space between the heat mat and the tray by elevating it an inch or so. I use another flat tray upside down to give the right spacing. Heat mat thermostats are also available to help regulate temperature.
Over-lighting a fresh cutting can easily cause it to droop and stress. We are trying to minimize water transpiration from the leaves once the cutting has been made, so soft light is preferred for this process. One T5 over a single flat tray is adequate lighting. The Super Sprouter Combo is a great example of an ideal set-up. If using a larger T5 unit (4 to 8 bulb), put the light higher than you would with single T5 fixtures (roughly 36”above the plants). This will ensure that you don’t overlight the fresh clones, and will also increase your cloning square footage.
Fresh Rooting Gel (or Liquid)
Your rooting solution should be fresh for best results. A gel that has separated and doesn’t look consistent has more than likely gone bad and should be discarded. An old gel or liquid can actually do more harm than good. It is also good practice to pour off what you think you may use into a separate container like a shot glass or floral stem, and use that to dip your cuttings into. Contamination into your stock bottle with shorten its shelf life.
Let them ROOT!
Lastly, I know that folks get impatient and want to check on their clones to see if they’ve produced roots, but give them space for at least five days. I tell customers to not even open the lid for that long if they can see that the clones look healthy inside the dome. Disturbing the media to check for roots can just delay the process. Patience is key when it comes to success.
I hope these simple tips will be helpful to you. Feel free to comment if you have any specific questions, and we will be sure to get back with you.