How to Use Rockwool in Hydroponics

How to Use Rockwool in Hydroponics - The Best Guide 2022 Hydroponics

How to use rockwool in hydroponics? One of the biggest issues for any hydroponic gardener is deciding what is the most productive gardening medium that can satisfy their requirements. With a variety of options, it’s difficult but one always rises to the top.

It is a versatile substance and has been utilized for more than 40 years. It is perfect for seedlings and can be used in certain systems, but there are many questions about how best to benefit from this material.

We will take examine everything you must be aware of about Rockwool and the benefits you will gain from its use of it within your yard.

What are Rockwool Cubes?

What are Rockwool Cubes?

Similar to the texture of steel wool It is a thick mat made up of long fibers composed of naturally-derived fibers. Chalk and basalt rock are combined, and later melted at a high temperature (approximately 3000 degrees Fahrenheit) to create the lava. Then, people dump the lava into a spinner to make fibers in a similar fashion to creating cotton candy.

Because of the process of firing the Rockwool cubes are both biologically and chemically inert. This is a great environment for the growth of hydroponic systems of growing.

Once the fibers have been spun and mixed, they are then blended with binding agents before being formed into mats. They are then cut into different sizes of slabs and cubes for sale to customers as a medium to grow plants.

Cubes of Rockwool are very popular with hydroponics growers and traditional farmers due to their superior structure. When the fibers are spun, it forms a structure that perfectly suits to hold the water, while also retaining more oxygen than standard soil mediums. The higher capacity for water retention and oxygenation in the root zone is extremely advantageous when planting seeds and cuttings to propagate roots.

Another benefit of Rockwool cubes is that they are believed to be natural, even though they are manufactured. This is due to the fact that they come from basaltic rocks and chalk which are both natural components. Being a natural item allows them to be used in organic farming systems and thereby increasing their appeal.

Their non-irresistible nature also means that growers are able to quickly alter the conditions in the root zone to satisfy the demands of plants. Insufficient Cation exchange capability (CEC) stops the nutrients from being altered through the growing medium or connected and rendered unusable to plant uptake. Cubes can be cleaned quickly with water that is fresh, which allows the leaching of fertilizer salts away.

The Rockwool cubes are available in several sizes. The smaller ones are great for beginning seeds as well as propagating stems and leaf cuttings. The larger cubes are utilized by gardeners to cultivate smaller plants.

What Can I Grow Using Rockwool Cubes In My Hydroponic Garden?

How to Use Rockwool in Hydroponics

There are many varieties variety of plants and vegetables that can be grown using Rockwool. Commercial growers utilize it to germinate lettuce prior to when they transfer them to NFT systems, homeowners are able to use larger Rockwool blocks to grow diverse leaves, greens, herbs, tomatoes, peppers, and cucumbers to name a few.

Growers who utilize their system to cut flowers have found that both Gerberas, as well as Roses, are thriving when they are planted in Rockwool.

As new hydroponic gardeners discover the advantages of Rockwool and begin to consider ways they could benefit from making use of it in their garden. The uses for many will fall down to the germinating seeds or the purpose is to clone new plants However, bigger blocks can be more flexible than making use of Rockwool plugs to start to accomplish this.

Whatever the application or purpose, the properties of Rockwool make it an ideal medium to grow plants. With respect to its dimensions, it is able to hold an enormous volume of water. This makes it ideal for environments where there are dry periods and the growers don’t want their medium to completely dry out.

This also serves as a safety measure in the event of power interruptions, or if there is a timer or pump malfunction.

If water retention was not a sufficient reason to consider for you, then the ability to hold around 20% oxygen in fibers could be. This provides plenty of oxygen into the plant roots and makes it very difficult to water their plants.

Larger cubes of 4 inches are used to grow the larger plants that we have seen above However, the plugs that measure around 1.5 inches are typically used for germinating and Cloning.

Rockwool can make it easier for novice growers during an otherwise stressful period. By using Rockwool it is possible to keep their seeds moist enough to not sit in a humid environment. When you want to clone an old plant will be taken from a different plant and planted in order to become a plant that is it’s own.

This could be a more profitable and cost-effective method of cultivating plants in the hands of many farmers since it will be a similar duplicate of the plant which was the one that was donated.

In order for this method to be successful, there has to be a lot of humidity surrounding the cutting. If it is drying out too significantly, then the plant will go into self-preservation mode and cease to establish new roots.

Growing methods require being placed in a sterilized environment. The way they produce Rockwool implies that it is completely inert. The process of heating it through during its manufacturing makes it virtually impossible to get rid of fungi or bacteria getting into Rockwool.

Do’s And Don’ts of Using Rockwool Cubes

Do's And Don'ts of Using Rockwool Cubes

One disadvantage of using cubes made from Rockwool is the particular attention and consideration that need to be given when working with these cubes. While they are an excellent tool for growing hydroponics. However, they also have significant drawbacks that must be dealt with.

  • Do spend the time to properly prepare the Rockwool cubes prior to starting seeds or trying to root the cuttings. Their pH is naturally too high to allow for optimal plant growth and can cause problems and instability in the hydroponic system if left at this alkalinity.
  • Do use protective gear to ensure your safety while handling the Rockwool material. The fibers can cause irritation to the skin, lungs, and eyes, so it is essential to safeguard yourself. At a minimum, wear a mask that is dust-free to stop inhaling fibers in your lung. Also, it is suggested to protect your eyes as well as long sleeves when there’s the possibility of interaction with the skin.
  • Do sterilize the feed solution before running it through the cubes of rockwool. While it’s an artificial, inert substance, it may be susceptible to the growth of algae and bacteria that could contaminate the hydroponics equipment if it is circulated in a manner that is not properly treated.
  • Do eliminate the material in a proper manner after with the cubes. Like other growth mediums, the rockwool doesn’t consist of natural materials, so it is not able to be broken down over the course of time. When it is dumped in the garbage, it will stay there forever. Instead of throwing them out take the pieces apart and incorporate them into your garden or pots of soil to improve the retention of water.
  • Do use to soak rockwool cubes in case you intend to use them in a subsequent year of growth, or multiple seasons. This is achieved by using steam or by pouring boiling hot water over them to eliminate any fungus or bacteria which may be living in those fibers. Some websites recommend chemical treatments to clean rockwool cubes before reusing them but this is a risk unless you’re certain you’ve washed all the chemicals that sanitize the fibers.
  • Don’t crush the cubes if they’re wet. If you’re looking to take certain amounts of water that has accumulated in the cubes following preparation in a pH-controlled solution, it is best to shake them with a gentle shake. They are famous for their inner structure, which provides them with a high water-holding capacity and oxygen circulation by compressing the structure and reducing the benefits that they’re famous for.
  • Don’t forget that rockwool is inert, and is unable to provide any nutritional value to plants that grow within the cubes. Everything that plants require comes from the nutrients that they receive.

How to Prepare For Hydroponics Rockwool

How to Prepare For Hydroponics Rockwool

Prior to using your rockwool within the hydroponics process, it’s essential to get it ready to be used. As opposed to other pH-neutral hydroponic media, such as Hydroton or Coco Coir, Rockwool is naturally high in pH, usually about 8.0 due to the method of manufacturing. In the course of manufacturing, there is an amount of lime put on the rockwool fibers. lime neutralizes acidity and naturally elevates the pH.

The pH range of 8.0 isn’t the ideal pH for hydroponic growing plants and must adjust to a degree that is more suitable for growth. A higher pH can make the plant’s essential nutrients unobtainable for plant consumption, which can cause symptoms of deficiency. The majority of plants prefer to thrive in moderately acidic environments, and they will gain when the pH of rockwool cubes is reduced to a less acidic state.

There are a variety of methods of preparing rockwool to be ready to use that isn’t complicated, but they could take time-consuming. Because of this, you’ll be required to budget for several days for the preparation of rockwool prior to getting it ready to use.

The first step to making the rockwool is to soak it in water that’s acidic to reduce the pH. Acidic water dissolves the lime created on the fibers during the process of making them as well as the pH decrease to a lower level.

It is recommended to use distilled water due to it is pure, however, tap water will work in an emergency if it’s the only option that is available. Reduce the pH gradually until it is at 5.5 and it is essential to ensure that the pH does not fall below 5.0 since it can begin to damage the fibers of the rockwool in the event that it becomes too acidic.

After that, submerge the rockwool cubes into the water and let them absorb for approximately 24 hours. Once they are done taking a bath, remove them from the excess water and introduce them into the hydroponics setup and allow the system to operate without the need for plants till the pH remains somewhere between 5.5 and 6.0 which means the cubes remain stable and are able to be utilized.

Step-by-Step Guide How To Use Rockwool In Hydroponics

It might seem daunting to make the initial several times, however, it is actually quite simple and productive when you use this medium to grow.

These are steps you need to be following when planting seeds.

  1. Rockwool preparation: soak your cubes thoroughly in pH-adjusted water. They must have a pH range of 5.5 up to 6.5.
  2. In the hole from the bottom of the hole put two seeds. With a small object like a toothpick push the seeds towards the lower part inside the plug.
  3. Make sure you pin the edge of the hole to close it or cover it with a tiny piece of Rockwool.
  4. Connect all the starter plugs into an infant tray. Place a humidifier on the top. Maintain the temperature between 70 and 80 degrees Fahrenheit.
  5. Make sure to check every few days and make sure that your rockwool cubes aren’t drying out. Use water sparingly, or spray them with a bottle of water.
  6. When you can see the seeds sprouting, take the plugs from the dome and put them under the growing lights.
  7. If you spot an established seedling, cut away the shorter one in order to limit the growth. Do not attempt to cut off the smaller plant because it could cause damage to the branches of the larger seedling.
  8. If they are two and three inches You can then transplant them into your system. If you do this there is no need to take off the starter plug. This can be directly inserted into the growing medium of your preference.

Steps for Propagation Using Rockwool in Hydroponics

Propagation of plants can be difficult for novice growers until they know the best places to cut their donor plants. However, the procedures for making use of the Rockwool cubes are not much more difficult than in the case of seeds.

  1. Be sure that you’ve got your Rockwool cubes have been thoroughly soaked with acid-treated water.
  2. Be sure to give your donor plant plenty of water the night before the time you start the process of propagation.
  3. Use the primary stems of your plant that you are donating and trim 3 to 4 inches of the leaf stem as close as you can to your main stem. Take care not to hurt the node.
  4. Use the cut end to dip it into a rooting hormone.
  5. Place the cut in the cube. it’s inside your cube however, be sure that it doesn’t begin to rise from the base.
  6. Use your tray as a nursery with you and then half fill with perlite and vermiculite.
  7. Put the cubes on top of the growing medium.
  8. Shut off the dome of moisture to seal in the moisture and keep the temperature at approximately the 80 degree mark.
  9. As soon as roots start appearing The lid should be opened slightly and gradually increase the number of roots following.
  10. Take the dome off completely when the first roots begin to appear.
  11. When the roots start showing through the top of the cub transfer the cub to your body.

What Size Rockwool Cubes Should You Use?

It is also available in different densities that are measured using”denier”. A greater denier Rockwool is more able to absorb water than the lower deniers.

If you’re making use of Rockwool blocks to begin seeds, or to add an extra layer of protection for plants that grow on the top on top of Rockwool slabs, it’s recommended to use fabrics that are lightweight since these types of applications don’t require the use of a heavy-duty protective.

Rockwool is available in starter cubes which are specifically designed to propagate. The 1x1x2 inches cubes and 2x2x1 1/2 inch cubes are covered in plastic. The 1.5-inch cubes are suggested, to begin with. They are compatible with regular spacers and can be moved onto blocks or to any other suitable growing medium.

When Should You Transplant Rockwool Seedlings?

When Should You Transplant Rockwool Seedlings?

Seedlings are best transplanted after they’re about three weeks old. This is when the rockwool cubes are sprouting roots from all directions.

By doing this, you will be able to give your plants greater access to water, nutrients (nutrient solution), and oxygen, while reducing exposure to pathogens and pests.

The benefit of this method is that it requires less effort in hydroponic gardening since you don’t need to remove the plastic wrap. You simply need to unpack these cubes in the location you want to plant them in at the time you’re ready to plant.

The downside here would be when you are expecting crops like tomatoes or cucumbers. tomatoes when harvest time is everything since they take longer to grow in comparison to other plants. It is because of their capability to absorb water only via their root systems, and not via their leaves.

Look also – Transplanting Aerogarden Plants To Containers Ultimate Guide 2022

Conclusion Rockwool Cubes

The rockwool cubes are a vital product in the rapidly growing hydroponics business. Basaltic rocks naturally occur in nature and chalk is melted at extremely high temperatures in hot lava. The lava is then placed into a spinner to form long fibers, which are then fashioned into cubes or blocks to allow for ease of handling.

Cubes made of rockwool are popular because they retain moisture and oxygen well, and never hinder the growth of roots. With a range in sizes, shapes, and dimensions and apprehensible to virtually any setup used by growers.


Is rockwool good for hydroponics?

The use of rock wool has numerous advantages in hydroponic production The process of making the rock wool fibers using the molten rock and the plastic wrap around growing slabs assures that the product is clean and free of the seeds of weeds, pests, and pathogens.

Should you soak rockwool in nutrients?

Ideally, the rockwool should be submerged in a solution of nutrients adjusted by pH 5.5 until the rising bubbles have gone.

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