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growing weed with rockwool

Growing weed with rockwool

Over the 4th week and until the end of the 5th week of flowering we will again have to increase the frequency of irrigation to 4 waterings at day. The first and the last irrigation should each last 2 minutes, and the remaining two waterings should be 1 minute, distributed evenly through the day. EC levels should remain at 1.0 to 1.2, always taking into account the condition of the plants. We should keep the pH at 6.0 allowing it to fluctuate up to 6.2 to lower it again to 6.0 with pH down.

Germination in rockwool

In the 8th week of flowering, plants will receive the same number of irrigations, at the same duration as in the previous week, although we can raise the EC to 1.8 depending on the condition of the plants.

To transplant the seedlings, we insert the small 3 x 3cm cubes into the 7.5 x 7.5cm Rockwool blocks taped to the slabs. As we do this, we must push gently and slowly until the small cube is well inserted into the larger block, taking great care not to break or damage any roots in the process.

5. How to grow in Rockwool

Hydroponic cannabis grow using Rockwool

The process of rooting cuttings in Rockwool is very similar to other cloning methods using jiffies or coco-coir (see how to take cuttings).

We will start the germination in two wet paper towels, placed between two dishes in order to maintain a constant humidity and facilitate the germination of the cannabis seeds. Once we see that the seed casing has cracked open and the root appears, we can very carefully transplant them into the stabilised Rockwool cubes and, once established, we can perform the transplant to the slabs.

2. How to stabilise Rockwool

Once the Rockwool cubes have a stable pH as described above, we can proceed with the germination of the seeds we intend to use in our grow.

We can maintain this irrigation schedule, varying according to conditions and demand, until the first week of flowering when we will start to gradually increase pH from the initial level of 5.5 , raising it slowly over the course of the week to a level of 5.8-5.9 suitable for this stage of flowering.

Larger rockwool cubes that are 2×2-inch or 4×4-inch squares are useful for cloning, early grow phase, and for platform drip irrigation systems in which the cubes sit on top of rockwool slabs, which are long, thick cuts of rockwool configured for use in ebb-and-flow systems.

Understanding The Rockwool Presoak

For marijuana growers wanting total control over the nutrient elements and compounds their plants absorb through their root zone, rockwool has long been the reliable choice.

Rockwool Presoaking Drainage & Moisture Logistics

Basalt starts out as lava; rockwool manufacturers turn it back into lava so they can spin it at high speeds to create a porous, wool-like material that has the texture of cotton candy.

Growing weed with rockwool

Since you took the extra time at the beginning to soak it, it’s able to keep the pH you gave it in the first place.

You don’t need to use Rockwool if you are planting outdoors, as it won’t work very well. It’s more of an inside technique, so be sure that you have a setup indoors that will work well with this substrate. Outdoor planting is better suited for soil, since it will be less fickle and you won’t have to watch it as closely.

This permits the plant to start to develop into the vegetative stage without locking down roots. This means when it comes time to transplant the plants into soil, you can remove them without damaging any part of the plant, especially the delicate roots.

Making clones

One reason to use Rockwool is when you need to germinate seeds. Since they are able to keep the seed moist, this can be advantageous. You will still need to germinate your seeds for a few days prior to adding it to the substrate, but after that, you can place it in there to allow it to keep growing.

This material is also a type of insulation, so you can use it to insulate any part of your operation as well. This also lets you know where you can purchase this product, if you need to buy some. You should be able to get some at home improvement stores, online, or at other specialty stores.


At hydroponic stores, you may even be able to buy small squares of it that won’t need to be cut or reshaped.

Due to this substrate’s unique properties, it is impossible to overwater your plants when you’re using it. You can even leave the plants in the same piece without having to move them throughout the process.