Grow Q&A: Cleaning Grow Rocks

Dear Dan, I’m a hydroponic grower and I use Hydroton (grow rocks) as my medium. What is the best way to clean the rocks? Also, what’s the quickest way? Thanks! – Hydro Tom

Dear Tom,
The best way is not always the quickest and vice versa. It’s important to properly clean and sterilize the rocks between every use. Grow rocks are meant to imitate naturally-occurring lava rocks and are made using heat to puff them out. This creates many tiny spaces within them allowing oxygen to permeate to the roots that cling to the airy “stones” but also creates plenty of room for molds, diseases viruses to hide as well.

The easiest way I’ve seen people clean their rocks is in a big washtub with a drain or a large industrial-sized sink. A bathtub works well also. The rocks are soaked in piping hot water and agitated to remove any root particles that remain stuck. Then, they soak in a mild bleach solution (10 percent or less) for an hour or so, only to be thoroughly rinsed again in plain hot water. After drying, they are ready to re-use. Extra care should be taken if you’re previous harvest suffered from any root maladies.

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