How to clone plants using Rockwool

In this video, Paul gives a step-by-step explanation on making clones (taking cuttings) with Rockwool as a grow media. Once your clones have rooted they can be transplanted to any type of media or soil.


Step 1: Preparation – Always use a new or disinfected tray and dome. You want your tray and dome to be set up in a room with proper ambient environment, with a temperature of 75°F and a humidity level of about 50%. Next make sure that your tray is not sitting on a cold surface. Some people like to use a heat mat, but this will sometimes cause your starter cubes to dry out too quickly. A towel or thick piece of cardboard will do fine. They just need to be off of the cold surface. Hanging above your dome should be a 2′ long 24 watt T5 light, this will be plenty of light for starting cuttings. Also, pre-soak 20 (minimum) to 30 (maximum) rockwool cubes in water at 5.5pH. Starter cubes will need to soak for about 20-30 minutes.

Step 2: Put Cubes In Tray – Once your 20-30 cubes are done pre-soaking we are going to place them in the tray, evenly spaced of course. When taking each cube out of the pre-soak solution you want to give them each a few good hard shakes, but without squeezing the cube as this will change the consistency of the rockwool. If done properly, you should be able to hold the cube with one corner lower than all the others without any water dripping. Do this to all of the cubes, even the ones that you aren’t expecting to put clones in. Once all the cubes are placed in the tray, check to make sure no additional water has drained from the cubes. Use a paper towel to soak up any standing water you see in the tray.

Step 3: Cutting your clones – Always be sure to use new growth (i.e. tops, suckers, etc.) for making clones. You want to cut at a 45° angle right where the new growth meets the main stalk, then remove all but the top two leaves. The angled cut will give your new cutting more surface area for new root growth. Trimming the excess foliage gives the plant enough to still photosynthesize, but not too much so that it can focus more on forming those new roots. Next, you are going to dip about 1/4″ of the cut end into a rooting hormone (i.e. Hormex, Clonex, Olivia’s, RootTech, Dip’n Grow, etc.). There are many out there, but the key is the active ingredient Indole Butyric Acid, so don’t be afraid to try different ones and find what works best for you. You don’t have to use a lot. A little goes a long way.

Step 4: Cuttings in Cubes – Immediately after dipping your cuts into rooting hormone you will want to firmly but gently push the stems into the pre-existing holes in your rockwool cubes. If the whole seems too loose you can also go off to the side of the whole, or even flip the cube upside down and use the underside. Also, remember, you are taking as many cuts as you need and filling the cubes accordingly. You should have 20-30 cubes in your tray. Whatever you do not put a clone in should still remain in the tray for humidity purposes later.

Step 5: Put on the Dome – Once you have taken all your cuts, and have them all placed in their cubes you can put on your 7″ humidome, with vents closed at this time. Place your tray and dome centered underneath your 2′ long 24 watt T5 light, and have the light about 1″ above the dome. Fluorescent light is low intensity so it needs to be this close for the plants to get the proper amount of light and warmth. The warmth will slowly evaporate the water from the cubes, creating condensation on all four sides of your dome each day. The slow drying process of the cubes is what triggers the plants to “chase” the water and pop roots. Once a day you should remove the dome, shake off the condensation, and dry up any standing water that may be in the tray. If you do not have condensation on all four sides each day make sure that your tray and dome are not being hit directly by cold air (i.e. air conditioning) or direct heat other than the T5 light. Don’t forget, ambient room environment should be 75°F and 50% humidity.

Step 6: Getting Them Ready To Go– So at this point you have been taking the dome off once a day and shaking out the condensation. Also, wiping up any standing water that may have been accumulating in the tray. At about day five you will want to check the cubes weight. If they are feeling light then you will need to add some water. Add water directly to the cube, and just enough to rehydrate it. No water should drain through the cube and into the tray, but if it does wipe it up at least. Also check the underside of the cubes to see if you there are any signs of roots. Once you start to see a few roots poking through the bottom, you can crack the vents on the dome. They can now drink water from the cubes via roots, instead of having to absorb it through the air. You will continue to open the vents more and more each day. Once they are opened fully, the next day you will be removing the dome completely for a couple hours. Leave the dome off for a couple additional hours the day after, and then completely by the third or fourth day of dome removal. After they have spent a full day with the dome removed and are still perky and healthy, they are ready for transplant!

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