Rockwool for Indoor Cannabis Production

Professor DeBacco

Many Potential Uses for Rockwool
Rockwool can be used at any stage of growth for cannabis production.
Some growers prefer to use it only at the early stages
Others will grow plants in it for the entire growing cycle

What is Rockwool?
Rockwool is a lightweight substrate made from spinning molten basaltic rock into fine fibers.
It is commonly used in hydroponic growing set-ups, especially in commercial settings.

It is formed into a range of cubes, blocks, growing slabs and granular products.

Rockwool Properties
Rockwool can have a good balance of being able to hold water and still provide sufficient aeration to the plants roots.

Hydroponic set-up often use rockwool because it has a slow drain time which allows for feeding/watering to be very specific.

Rockwool Benefits…
Natural balance of water holding and aeration conducive for root growth and development.
Lightweight which reduces the shipping expenses
Provides a sterile growing environment.

Watch Out For…
Algae growth
Disposal due to the fact it does not compost/break down.

Rockwool Options
Starter plugs

How To Prepare Rockwool
Check with the manufacture
At the very least rockwool will need a presoak in water
Some needs to be soaked in water to help regulate the pH
It is still a good idea to check the soaking waters pH before, during and after the rockwool soak to help ensure there will not be an unexpected stress on the plants.

Water Soak Targets
Depending if you are using Rockwool for the propagation or grow cycle specific targets may vary.
However, in general…
pH: 5.3-5.5
ppm: 400ppm
Temperature: 65-70F
Soak for 2-5min. To ensure air bubbles are removed and full absorption has occurred

Link to Lecture Slides:

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