1. Fill up a shallow bowl with water and test the pH. Add your pH-down product until your meter shows an acidic reading of 5.5.
Rockwool also poses a potential health hazard to growers. New Rockwool cubes can contain a lot of loose fibres and dust. These particles can end up in the air, and even on your skin and in your eyes, mouth, and lungs. Much like asbestos, tiny fibres can build up in the lungs over time if you work with new Rockwool cubes every day.
Flush your soil or hydro plants one week before harvest. Restrict nutrients and only provide water to remove excess salts from the soil and allow plants to use up the last of their supplies. This will result in tastier and smoother buds.
Although they take a long time to break down, growers can shred their used blocks down as finely as possible and throw them onto the compost pile. Over time, key elements within basalt rock will leach into the compost and add a nutritional kick to your future soil.
These small particles are classed as “fine mineral fibres”, which the Environmental Protection Agency (EPA) in the United States has identified as probable human carcinogens  .
Tossed whole onto a compost pile, Rockwool will take an extremely long time to break down—hence why many growers see it as bad for the environment. You should aim to shred up your used cubes as finely as possible to accelerate this process.
Cannabis plants have different nutritional demands during the flowering stage. Clean out your hydroponic nutrient reservoir and fill it back up with a flowering formula. If you’re growing in soil, start watering your plants with bloom nutrients to ensure big, healthy buds.
For soil/coco/etc., peat plugs generally fare better, but ultimately germination will be nearly identical for these two germination mediums.
In this lesson, we will learn how to start your own seed with Rockwool Cubes. Below is a detailed guide to success with Rockwool, and a step-by-step video tutorial can be found at the bottom of the page.
What Plugs Should You Use?
Germinating with starter plugs or cubes is easy and the most reliable method on this list.
This method allows you to start your seed directly in your planting medium, but if you aren’t careful with this technique, you can run into trouble.
This is by far the best method to germinate weed seeds.