What is rockwool?
Rockwool, commonly referred to as stonewool, is a hydroponic growing medium derived from basalt. This is one of the more common soilless options indoor hydroponic growers choose, and rightfully so, as it has a number of benefits.
Commercial growers often claim rockwool is the ideal substrate for growing hydroponically, due to its ability to hold water while retaining sufficient aeration. Rockwool drains very slowly, allowing for a precise manipulation of hydroponic nutrient dosing between vegetative and flowering cycles. Most rockwool comes packaged very dry, and thus growers need to pre-soak it in water before planting. It is also important to avoid overwatering with rockwool to prevent algae growth.
What are the benefits of rockwool?
- Rockwool holds water well, but doesn't absorb much of it, making more available for roots.
- It is a well aerated growing medium, proving sufficient oxygen to the root zone.
- Lightweight, saving on shipping costs, but still stronger than other hydroponic growing mediums.
- Rockwool provides a sterile growing environment.
- Once you are done with one grow, you can keep using your rockwool cubes!
Rockwool is not without drawbacks, however. It can be very hard to dispose of, since it doesn't break down. It is also important to adjust the pH of your rockwool when you get it, as rockwool tends to have a high natural pH.
What are the different types of rockwool?
Rockwool comes in a number of shapes, and since it easily breaks apart, it can be formed into any size necessary. The most common types of rockwool are:
Rockwool starting plugs and rockwool cubes are great for seed starting, and can be used through the life of the plant. Once roots begin to pop out of the plug or cube, growers can simply transmit the cube right into a net pot or other hydroponic container
Who should use rockwool?
We recommend intermediate growers use rockwool as their hydroponic grow medium. Rockwool requires regular watering and feeding, and it retains moisture well, but it can be tricky to find the sweet spot. The rockwool should be damp, but not soaked. If you are germinating, you cannot go wrong with rockwool.
For more information on hydroponic growing medium, check out our full guide on all types of grow media!
If you have any questions about which hydroponic grow medium is right for you, call 888-815-9763 and let one of our experienced growers help you today!