1. Introduction to stone wool

Rockwool is a popular substrate in cannabis cultivation that is made from molten rock, usually basalt. The molten mass is processed into fibers and formed into blocks or mats. Rockwool provides excellent growing conditions as it allows for optimal water and air retention.

Compared to other substrates, rockwool is characterized by its high water holding capacity and excellent aeration. These properties make it an ideal medium for root development and nutrient absorption of cannabis plants. In addition, rockwool is inert, which means it does not release its own nutrients and is free of pathogens and pests.

Rockwool comes in a variety of forms, including blocks, mats and cubes, suitable for different stages of plant growth. Due to its versatility and effectiveness, rockwool is very popular with both hobby gardeners and professional growers.

In the next sections of our grow guide, we will go into more detail about choosing the right rockwool, preparing it, how to use it optimally, and how to care for it and maintain it. This way, you can ensure that your plants grow and thrive in the best possible conditions.

Always pay attention to the legal framework of the Cannabis Act (CanG) in Germany, which legalizes the cultivation of up to three plants. You can find more information on this in the chapterLegal situation.

3. Preparation of the rock wool

Rinsing and buffering

Proper preparation of rockwool is crucial to creating optimal growing conditions for your cannabis plants. Rockwool should be thoroughly rinsed and buffered before use to remove dust and excess salts and to stabilize the pH.

• Step 1: Rinsing the rock wool:Start by rinsing the rockwool thoroughly with clean water to remove dust and loose particles. You can use a bucket or tub for this. Submerge the rockwool and stir it to ensure that all contaminants are rinsed out.
• Step 2: Buffering the rock wool:After flushing, the rockwool should be buffered to stabilize the pH. Fill a bucket with pH-adjusted water (pH 5.5-6.5) and submerge the rockwool for at least 24 hours. This helps to stabilize the pH and optimally prepare the rockwool for the absorption of nutrients.

Enrichment with nutrients

After flushing and buffering, it is advisable to enrich the rockwool with a light nutrient solution. This ensures that the plants have access to important nutrients right from the start.

• Step 1: Preparation of the nutrient solution:Mix a weak nutrient solution according to the manufacturer's instructions. Make sure the nutrient solution has a pH of 5.5-6.5.
• Step 2: Soaking the rock wool:Dip the rockwool into the prepared nutrient solution and let it soak for several hours. This helps to enrich the rockwool with important nutrients and provide the plants with optimal nutrition.

Checking the pH value

It is important to check the pH of the rockwool before adding plants. Use a pH meter or test strips to make sure the pH is in the optimal range.

Careful preparation of the rockwool is a crucial step in growing healthy and strong cannabis plants. In the next chapter, we will look at planting the plants in rockwool and show you how to position and care for your plants in the best possible way.

5. Irrigation and drainage

Irrigation techniques for rock wool

Watering your plants in rockwool requires special attention as rockwool offers both high water holding capacity and good drainage. Here are some proven watering techniques you can use:

• Drip irrigation:One of the most effective methods is drip irrigation, which delivers water slowly and evenly directly to the roots. This technique minimizes water loss and ensures that the plants are continuously hydrated.
• Flooding and drainage:This method is particularly suitable for hydroponic systems. The rockwool is periodically flooded with water, which then drains away again. This ensures that the roots receive sufficient water and nutrients without drowning.
• Manual watering:If you water manually, make sure to moisten the rockwool evenly without oversaturating it. Water slowly and watch the water seep through the substrate to ensure that all of the rockwool is moistened.

Ensure optimal drainage

Good drainage is crucial to avoid waterlogging and to provide sufficient oxygen to the roots. Here are some tips to optimize drainage in rockwool:

• Correct pot size and shape:Use pots with adequate drainage holes and ensure that excess water can drain easily. Make sure the pots are not too large to ensure even moisture distribution.
• Lifting the pots:Place the pots on a raised surface or use special drainage trays to ensure that excess water can drain away properly. This will prevent the roots from sitting in standing water.
• Regular controll:Check the moisture content of the rockwool and the drainage regularly. Use a moisture meter to make sure the rockwool is not too wet or too dry.

Moisture management

Proper moisture management is crucial for the healthy growth of your cannabis plants in rockwool. Make sure that the rockwool is always evenly moist, but not wet. A moisture meter can help you monitor the optimal moisture level.

Using these watering and drainage techniques, you can ensure that your plants receive the optimal growing conditions in rockwool. In the next chapters of our grow guide, we will look at nutrient management and the care and maintenance of rockwool to ensure the best possible growth of your plants.