Rockwool is a popular medium for growing your plants. Therefore this article will cover using Rockwool for growing plants and the proper way to dispose of it. – Gro Indoor
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How to Grow Plants in Rockwool

by 09 Apr 2023

How to Grow Plants in Rockwool

Rockwool is a popular medium for growing your plants. If you don’t have access to coco or soil, you can always use Rockwool to start growing your plants. Additionally, it is one of the unique mediums for growing plants. For a plant lover, you cannot deny the benefits of Rockwool.

Therefore this article will cover using Rockwool for growing plants and the proper way to dispose of it. Many new growers are unaware of how to dispose of Rockwool, creating many problems properly.

What is Rockwool?

Rockwool is a substrate for a lot of growers in hydroponic operations, as well as a valuable addition to clones and seeds.

Basically, Rockwool is artificial and made by melting chalk and Basalt rock at high temperatures. Therefore, the process creates a substrate that resembles steel wool in appearance and texture. Further, its structure is composed of long fibre strands, making it durable in addition.

Rockwool is also chemically inert, meaning this medium has no nutrient charge. There is zero EC or PPM content in Rockwool. Therefore, it is one of the unique advantages of using Rockwool, which we'll discuss in detail below.

Different Types of Rockwool

One of Rockwool's benefits is that it comes in a variety of sizes and forms, making it a very adaptable medium for growing your plants.

Rockwool is ideal for growing plants to their maturation or clones and seeds.

Rockwool is most popular in the form of blocks and cubes. However, it is also available in the form of starter plugs, mats, and slabs. Rockwool is available at in the following forms:

We also have Block Covers for insulating your Rockwool and aid with retention. Rockwool is a common byproduct of construction for insulation purposes, so be careful when you search for Rockwool on the internet.

No need to worry, though, as this article covers everything you need to know about Rockwool! Now we'll cover some of the significant benefits of using Rockwool to grow plants.

Benefits of Rockwool

As we mentioned earlier, one of the most significant advantages of Rockwool is that it is chemically inert. As a result, the nutrients you feed your plants will not react with the Rockwool. Therefore, it will give you a greater level of control over your nutrient feed.

In addition, the potential of your feed reacting with the soil should not be taken into consideration while creating a feeding schedule, substantially simplifying the process.

Another advantage that we touched upon briefly is how versatile Rockwool is. As you can get them in various shapes and sizes, you can also use them in conjunction with other grow media.

For example, you can plant seeds in a Rockwool cube. When the seeds have significantly grown, you can take the cube as it is and directly put it into your hydroponic system or soil. It’s even possible to place the seedling in a large Rockwool cube and continue growing!

How to Grow Plants Using Rockwool

Using Rockwool is easy enough, but you need to be mindful of some things. Therefore, it's always best to wear PPE when handling Rockwool and prepare your Rockwool in the prescribed manner.


Use gloves and protective eyewear before you open the package which contains the Rockwool. Otherwise, the Rockwool fibres irritate the skin, eyes, and even lungs.

Always ensure that you’re wearing PPE whenever you handle Rockwool. Be careful that you don't inhale any fibres or dust.

Soak the cubes first

You’ll find Rockwool to be extremely dry when you take it out of the package first. Therefore, you should first completely submerge it in water till saturation before doing anything else. Thus, it ensures that your plants get abundant moisture.

However, before you start soaking the cubes, there are a few things you need to remember. Further, you need to hold the cubes in water, but they shouldn't be dripping. The best thing to do is soak them first, but ensure that you shake out any extra water. Excessive moisture can lead to your plants drowning.

Furthermore, you need to take care that you squeeze your Rockwool cubes. You do not want to squeeze roughly or strongly because it can destroy the cube structure, significantly decreasing its effectiveness as grow media.

Adjust pH

Rockwool cubes are naturally alkaline in pH terms. That's why you need to adjust their pH to make them suitable for plants.

Usually, it has a pH of 8 but needs to drop down to at least 5-6. Plants thrive best in a relatively acidic range. Therefore, one of the easier ways to do this is to saturate your cubes in the water with the requisite pH level.

Further, the water you use for watering your plants must have a suitable pH. The same goes for your feeding. If you don’t, you run the risk of depriving your plants of certain nutrients, which in turn, can cause deficiencies in your plants.

Disposing of Rockwool

Remember that it is an inorganic compound, so it needs to be disposed of properly. Rockwool is non-biodegradable, so don’t just chuck it in the trash where it will ultimately end up in a landfill. Further, you can tear it up into small chunks and sprinkle those all over your garden. In addition, it will be helpful for your garden because it will improve water retention. It’s not harmful to your plants, so you need to worry about that!

It is the right way of disposing of your Rockwool; you get to reuse it, and your garden also benefits.

Last thoughts on Rockwool

This piece of writing covers every important detail about using Rockwool as a growing medium for your plants. Further, has a huge assortment of well-known Rockwool brands at reasonable pricing. We have Rockwool available in all its popular forms, including slabs, cubes, and many others. Hence, visit our website to explore more!

Jul 31st 2022
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