This week on the blog I wanted to talk about loose fill Rockwool, also known as Grow Cubes. This hydroponic plant media has been around for quit some time but is far too often overlooked as a grower’s media of choice. Let’s take a look at some of the advantages of Grow Cubes and how to use them to unlock their maximum potential.
Rockwool is a growing media made of basalt, one of the most commonly-occurring minerals on the planet. Grodan, the makers of Rockwool, takes the basalt and heats it up to extremely high temperatures and then spins it like cotton candy. This process creates a substance that looks similar to your attic insulation. Rockwool is full of many micro pores, allowing for a great ratio of air-to-water retention. I love Grow Cubes because they are almost impossible to over water, as they drain in a superior way compared to other media. This is because they are small little “crouton” pieces of Rockwool that create air pockets that allow for healthy root systems.
A huge advantage to using Rockwool Grow Cubes is that they are completely sterile and inert. This makes for a very clean grow space with next to no chance of bringing in pests or pathogens, like you might if you choose to grow in soil. They are extremely light-weight and easy to bring in and out of your grow space. Grow Cubes are also one of the easiest media to flush out any built up mineral salts from the hydroponic nutrients throughout the grow cycle. This allows the grower to flush his or her plants aggressively within a very short time period, whereas with soil or coco it could take up to two weeks to flush out built up mineral salts!
Grow Cubes work best with automated watering systems such as a top drip or ebb and flow. When irrigated properly, plants should experience rapid, healthy growth using Grow Cubes in these systems. I recommend irrigating your Grow Cubes three to four times a day during the lights on period. As the media drains so well, there will always be an abundance of fresh oxygen for your roots as well as the perfect amount of nutrient solution retained within the cubes themselves. However you choose to irrigate this media you cant loose!