Growing Clones in Rockwool Cubes

Rockwool is one of the best growing media used for indoor gardening. Many gardeners use Rockwool as a medium for growing their plants and vegetables. It increases the overall yield of their desired crop. When it comes to cloning plants, you can never go wrong with Rockwool cubes.

A warm, clean, healthy stock is a requirement to have successful cloning. Cold and damp environments delay rooting and increase the plant’s mortality. Get to know how to grow clones in Rockwool cubes in this article.

Benefits Of Using Rockwool Cubes As A Growing Medium

Using rock wool as a growing medium offers a wide range of benefits to the indoor gardener. Rockwool retains a lot of moisture and provides plants with sufficient aeration. This provides the roots of the plant to get enough oxygen required for propagation.

In addition, Rockwool increases the overall yields of your plant. They enable the plant to grow to full maturity within a short period.

You can easily break the Rockwool cube into several pieces to meet your needs. The Rockwool cube is also strong to ensure it does not breakdown through the growing cycle.

It is porous ensuring that it properly retains a lot of water. This is useful since materials that disintegrate choke up the systems supply components.

Moreover, Rockwool is cheap, makes it easy to transplant clones, and biodegradable. The ease of portability ensures that there is minimum transplant shock.

What You Require To Clone In Rockwool Cubes

Before you start cloning in Rockwool cubes, ensure that you have the necessary materials. This may be the difference between getting a successful yield and damaging your plants.

  • Fluorescent grow lights
  • An inch of Rockwool cubes
  • Cloning gel
  • A sterilized razor blade
  • Cutting board
  • Disinfected solid tray with a dome
  • Methylated spirit
  • No damp spray solution
  • Heating mat
  • Tray inserts to keep the Rockwool cubes upright and evenly spaced

One of the major challenges of growing clones in Rockwool cubes is getting the amount of water right. These cubes can hold a lot of water, which may slow down the rooting process and stem rot may set in.

Use distilled water or treated tap water to water clones. Take note that the water should always be at room temperature.

Procedure for Growing Clones using Rockwool Cubes

Growing clones in Rockwool has never been simpler. Follow the steps below to grow your clones successfully using Rockwool cubes

Step 1: Buy the right Rockwool Cube

It is important to get the suitable Rockwool cube for your cloning process. You can easily get Rockwool cubes in a hydroponics store. Choose the right size of Rockwool, for instance 1.5″ x 1.5″ x 1.5″.

However, do not confuse these cubes with germination cubes. They are larger, have a plastic covering on the side and an eighth of an inch wide hole at the center.

Step 2: Preparation of the Rockwool Cube

As mentioned above, use the highest quality of water to treat Rockwool cubes. Use distilled water, or treated tap water to rinse the cubes. Soak the rinsed cubes in a water solution for a night. The pH should be 4.5.

After removing the soaked cubes, ensure the pH of the water solution is 5.5. You will have to repeat the soaking process if your pH lies between 6.0 and 7.0.

After measuring the pH and finding that the pH of the water solution is 7 or greater, soak the Rockwool in a phosphoric acid solution. The soaking should be for thirty minutes. Consequently, soak the Rockwool cubes in a water solution with a pH of 5.5.

After a period of 8 to 12 hours, confirm the pH of the water solution. Again, ensure that the pH of the water solution ranges between 5.5 and 6. Once it attains this pH, you are set to plug your clones in the Rockwool.

Step 3: Preparation of the Cutting

Once your water solution attains the required pH, you are ready to begin growing your clones. Unlike planting seeds, growing clones require preparation of the cuttings. These cuttings are usually from the bottom part of a parent plant.

To get the cutting, cut transversely about a quarter of an inch below the parent plant for removal of nodes. If not, cut approximately an inch and a quarter below the initial node.

Ensure the spacing within the nodes is approximately an inch and a quarter before you remove the cutting. If you do not have that kind of spacing, using the sterilized razor blade, cut off the nodes in the lower part.

Once you have your cutting, dip it in the cloning gel for a half a minute. This removes any air bubbles that may be present.

Step 4: Placing the Clones in the Rockwool Cubes

After dipping your cutting in a rooting gel, plug it into the growing medium. Ensure that the Rockwool cube holds the clone in place. Place your cubes in a suitable growth basin at a temperature range of 80-85 degree Fahrenheit. The best option is selecting a solid growing tray fitted with a dome.

Use the No-Damp spray solution on the propagation tray with a dome. This is to ensure the dome is warm and humid. The dome traps enough humidity over the clones. Furthermore, you can place your clones under a fluorescent grow light for the whole day.

You should remove the dome over the propagation tray once every day. After the fourth day, you should get rid of the dome completely.

Step 5: Labelling

Faulty labeling often leads to the death of countless clones. It is possible to make mistakes from time to time, regardless of how good your memory is.It is therefore important to label every Rockwool cube.

You should label each Rockwool cube with the dates you expect your clones to start rooting. Additionally, label the different strains of clones.

Step 6: Watering

Watering the clones is necessary to provide them with the nutrients they require to develop roots and grow. The dome covering prevents water and humidity from escaping, therefore water the clones on alternative days.

In situations where you do not have a dome covering, water the clones once each day. Once your clones develop roots, usually within 5 to 10 days, water them at least twice every day. Remember to water the different strains of clones separately.

Tips For Using Rockwool Cubes


When growing clones in Rockwool Cubes, take note of the following tips to ensure that they successfully grow into healthy plants:

  • Use methylated spirit to sterilize the razor blade or scissors used in cutting the clones from the parent plant.
  • Wipe the cutting board with methylated spirit
  • Choose clones from a healthy parent plant. Selecting clones from such plants increases their chances of growing into healthier plants.
  • Once you open the rooting get, store it in a cool place like a refrigerator.
  • Remove excess dust from clones if you are using a rooting powder.
  • Do not use Rockwool cubes that collapse after placing clones in them
  • Remove clones that have brown roots, an indicator of rotting. Ensure that your roots are white.
  • Provide enough aeration to the cloning area.
  • Too much water is harmful in Rockwool cubes. They can hold a lot of water that can provide an environment for rotting of the roots or stems. Therefore, do not leave your Rockwool cubes in stagnant water.
  • Check your clones at least after the eighth day. Constantly checking on your clones may uproot the young roots.

You will find that growing clones in Rockwool cubes is quite easy to set up and use. It offers a wide variety of systems and situations for small growers. Use this four-step guide to grow your clones successfully.