Cloning in Rockwool

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One of the most exciting aspects of growing your own weed is the dream of one day raising the perfect plant with the look, the aroma and the potency you’ve always wanted. So now that your dream has come to fruition, where do you go from here?

There’s no need to reinvent the wheel. It’s time to try cloning.

There are a number of ways to clone a marijuana plant. In this article, however, we’re going to focus on cloning in rockwool.

What You Need

You won’t be able to clone anything without a mother plant, so put her on the top of your list! Be sure to select a mom-to-be that is healthy and hardy and who has been in her vegetative cycle for at least two weeks. You’ll also need:

  • Propagation tray and 7″ propagation dome
  • Seedling heat mat
  • Perlite that has been rinsed with water
  • Cloning gel
  • Shot glass
  • Rockwool cubes (1-1/2″ size)
  • Scalpels
  • Glass baking dish (8″ x 8″ is best)
  • Distilled water (70 degrees)
  • Cloning solution
  • Mycorrhizal fungi
  • Gallon-sized soup container
  • pH meter
  • pH Up and pH Down solutions
  • Bleach wipes
  • 99 percent isopropyl alcohol
  • Paper towels
  • Sterile, plastic gloves
  • Duct tape
  • Permanent marker
  • Recording journal
  • 16 oz. plastic cups in both red and clear variety

How to make the process of cannabis cloning successful

Once you’ve achieved the perfect mother plant, the last thing you want is for the clones you grow to lose the genetic qualities of their parent plant. You may even ask yourself: Do clones lose their potency?

Legal grow room with CBD cannabis in rockwool and automatic drip system

While the cuttings used to make clones will take the same genetic characteristics from the mother plant, it is important that you not forget the old “nature vs. nurture” argument and still give ample attention to such factors as soil pH, watering, nutrients, lighting, humidity and soil types. Even plants with the best genes have to be raised right!

Pre-soak the Rockwool cubes

Rockwool cubes have a natural pH of 7, which is too alkaline for clones to develop. As a result, they will need to be briefly pre-soaked in distilled water with a pH of 5.5.

Preparation of the marijuana clones

Once you’ve selected a suitable mother plant, feed her less nitrogen than you normally would as this will help her clones establish better roots. Also, be sure to take more cuttings than clones you plan to grow.

As good as it is to think positively, you are more than certain to lose a few during the cloning process.

Once rooted

When the cloning process is complete and your clones are newly rooted, they’ll require a steady diet of 18 hours of weak light per day and maintained temperatures between 72 and 77 degrees F. Soil should be kept consistently moist, though not saturated.

Expose them to little or no breeze. Continue this nurturing for six to eight weeks and they should reach adulthood.

Ten Easy Steps to Produce Healthy, Robust and Vigorous Clones

Cloning may seem difficult, but if you follow these easy steps, you should get the hang of it fairly quickly.

1. Sanitize

No surgeon prepares to cut into a patient’s body without first ensuring the environment for such an operation is sterile. Keep that same mindset when you are making a cut into the mother plant.

Before you get started, cleanse your tools and equipment with a paper towel that has been soaked with 99 percent alcohol and put on a pair of sterile gloves. Use bleach wipes to clean the surfaces of your workspace and where the tray will sit.

The last thing you want is for an infection to occur.

2. Setting Up

Put about a half-inch of well-rinsed perlite in the propagation tray, then place it on top of the heat mat and plug it in. Shake the cloning gel well, then fill the shot glass with it about half way.

3. Preparing the Cloning Solution

While the use of cloning solution is not absolutely necessary, using a low-level nutrient solution of this type will enhance your clones’ ability to develop healthy roots and cut down on the time they need to develop:

  • Pour a half gallon of distilled water in the 1-gallon container and adjust the pH to 5.5
  • Add 10 to 12 rockwool cubes (enough for a single tray)
  • Let the cubes soak for 5 minutes, then empty the water
  • Add the remaining 1/2 gallon of distilled water to the gallon container with the cubes
  • Following the product label, add the cloning solution to the 1-gallon container, stirring the cubes gently within the mix
  • Adjust the pH to 5.5

4. Setting Up the Cubes in the Tray

This step is easy-peasy. Just remove the rockwool cubes one at a time and place them in equally-spaced rows of two inside the tray. Be sure to leave plenty of space between cubes as you won’t want the cuttings they will hold touch each other while inside the dome.

This could lead to the development of too much condensation, which can lead to mold and mildew. When finished placing the cubes, pour half of the clone solution that remains into the glass dish and the other half in the propagation tray with the perlite.

5. Labeling

If you’re experimenting with cloning a variety of strains, don’t be the poor sap who forgets to label them properly.

View of a beautiful cannabis root that grows in a rockwool

It only takes a few extra minutes, and think what a shame it would be if you grew them out then realized you couldn’t recall which plants the clones came from.

6. Choosing and Removing Branches From the Donor Plant

When choosing which branches to cut, look for four distinct qualities:

  • Healthy branches
  • Clean, translucent leaf veins
  • A structure with six or more nodes
  • Stem diameters of equal size or larger than the diameter of the holes in your rockwool cubes

Once you’ve chosen your branches, make a clean, single cut with a sterile scalpel, and make it as close as possible to the main stem. Once this cut is made, place the cut end immediately into the solution-filled glass dish.

Try not to expose the cut part of the branch to air.

7. Making the Final Cut

Now here’s where the “operation” gets intense. You’ll need to make each final cut while your branches are still submerged in solution. For each branch, make the cut through the center of the of the fifth node from the tip of the branch, and make it at a 45 degree angle as this will provide more surface area for roots to form.

Once cut, quickly remove the cutting, shake off the excess water and place the cut end in the cutting gel in the shot glass for about 15 seconds. Then place each cutting into a separate hole in a rockwool cube taking care not to allow the clone to push through the bottom of the cube.

8. Set It and Forget It

Once the cubes have been filled, close the dome lid vents and recover the tray. Ensure that all of the leaves are able to move freely and are not pressed against the dome or caught under the lid. As the heating mat increases the temperature and humidity, you’ll begin to see condensation form on the inside of the dome.

Once the dome is completely covered, open the lid vents. Beyond that, let your clones be. Roots will begin to form, and in time you’ll see them come through the bottoms of the cubes.

9. Transplanting Using the West Coast Masters Clear Cup Method

Follow these simple steps for transplanting and you’ll do just fine:

  • Make slits for drainage around the bottom edges of the clear and red plastic cups
  • Label the red cups with the strain and date of each transplant
  • Fill the clear cups with organic soil until they are half full
  • Drizzle a small amount of mycorrhizal fungi over the soil in the clear cups
  • Place each rooted clone still in the rockwool cube in the center of each clear cup, packing the soil firmly just above the top of the cube
  • Place each clear cup with the new clone inside its corresponding labeled red cup

10. Watering

Take special care not to over water your plants when first transplanted. In this way, the roots will do their own “searching” for water and grow larger.

It’s also not necessary at this time to add fertilizers to your first watering as the soil is already nutrient rich. A nice feature of the West Coast Masters Clear Cup Method is that you can more easily monitor soil condition and root growth simply by removing the clear cups from the red cups.

If all goes well, your roots will reach the bottom of the cups in about a week and they will be ready for transplanting.


What kind of solution do I need to soak my rockwool cubes in?

You can make a simple solution using distilled water. However, some growers prefer to use a cloning solution or powder with hormones that aid the clone root. Gels tend to work better than powders as they provide a more even coat.

What pH do the cubes need to be soaked in?

Rockwool cubes have a natural pH of 7, which is too alkaline for clones to develop. Cubes should be soaked in distilled water with a pH of 5.5.

Cannabis seeds and roots of cannabis plant in laboratory glassware for research purposes, biotechnology concep

If you add nutrients, be sure to keep the nutrient pH as close to 5.5 as possible.

I am thinking of using a single HLG 260

HLG 260 lights are known to be an all-around good light product for all phases of cannabis growth, and their intensity can be adjusted with the built in dimmer switch. This is good because, whatever lighting product you use, you want to be sure it gives off fairly mild light that is not overly strong. Inexpensive CFLs or other fluorescent grow lights are also ideal.


Once you’ve successfully cloned your cannabis, you’ll want to keep in mind that their root systems are going to be a bit more sensitive and they’ll need a little extra care early on. In a matter of weeks, however, your plants should grow strong and be just as hardy as any other.

You can even feel comfortable with topping your clones like you would any other plant when the time comes.

But you already knew that, right? As in all things, nurture your plants well and they should reward you amply in the end.