Incorporating Volcanic Rock Dust Into Hydroponic Systems


At its most basic, hydroponic gardening refers to the practice of growing plants without soil. Given the massive degradation of our earth’s soils over the past century (which requires ever-increasing amounts of fertilizer to produce even moderate yields), it’s not surprising that more and more growers are turning to hydroponics to produce the crops that sustain us.

Still, hydroponic systems remain a mystery to many people. If anything, they think of plants that are grown with their roots suspended in water, without any growing medium at all. Yet this is just one technique among several, and you’ll find that hydroponic growers and indoor gardening enthusiasts are happy to explain the pros and cons of using different growing mediums—from coconut fiber to perlite, vermiculite and more.

So where does rock dust come in to play? Whereas ‘traditional’ growers are increasingly aware of the regenerative benefits of adding rock dust to their soils, indoor gardeners may wonder how to incorporate the product into their soilless systems.

In hydroponic systems, incorporating rock material can take on various forms and utilize different textures or particle sizes. Volcanic basalt, in particular, is well-suited to the needs of most indoor growers. For example, coarse basalt particles with fine particles removed can be used as a rooting media. Medium and fine basalt particles can be added to existing rooting media or to compost tea.  Very fine basalt particles that partially suspend in water can be added to hydroponic solutions where roots can latch onto particles. Be sure to exercise caution for pumps and other equipment with this last approach.

Volcanic basalt produces relatively little ambient dust and is easy to add to most indoor growing mixes. Moreover, a little goes a long way. A small quantity of high-quality volcanic basalt is all it takes to provide hydroponic crops with the essential minerals they need to stay strong, healthy and resistant to disease.

Savvy growers know that reliable plant growth and optimum yield depend on a balanced combination of nutrients, some of which are made available to plants quickly—and others that are made available over time. The slow-release benefits of crushed volcanic basalt make it an effective way to minimize deficiencies, particularly with fast-growing crop plants that experience periods of rapid nutrient uptake.


For best hydroponic results, look for products like Cascade Minerals Remineralizing Soil Booster that are listed by the Organic Materials Review Institute (OMRI) for use in organic production.