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Hydroton grow rocks are one of the most versatile growing mediums in the gardening world. You’ll be surprised to find out that hydroton are not rocks at all. They are actually an expanded clay product. This German product has rapidly gained popularity among hydroponic gardeners, but don’t be fooled—soil gardeners can also utilize this great growing medium.
Beneficial Properties of Hydroton:
Water Retention & Drainage
This material is filled with tiny pores, much like a microsponge. Because of this, it holds the perfect amount of water and drains any excess to prevent overwatering.
Unlike soil that compacts and reduces available oxygen over time, hydroton retains its shape and allows for continuous oxygen exchange, keeping your plant roots healthy.
In gardening, it is important to have a growing medium that isn't too acidic or basic. Hydroton is a pH-neutral product, so you won’t have to worry about any nutrient lockup or plant health issues due to unstable pH.
It is produced in large rolling kilns that ‘bake’ it into its final shape. Since high temperatures are used, hydroton comes to the gardener as a sterile product. This is highly beneficial because you don’t want to introduce disease and harmful bacteria into your garden.
Hydroton in Hydroponics
Hydroton is by far the most popular growing medium used in hydroponics. Although it can be adapted to any method of hydroponic gardening, it works especially well with Deep Water Culture, Drip, and Ebb & Flow systems. One important thing to keep in mind is that it can float in systems that completely flood the root system. These types of systems should avoid using hydroton to keep plant roots from being disturbed.
Hydroton in Soil
Despite the hype for hydroton in hydroponic gardening, it is an underrated addition to soil gardens. Soil gardeners—like hydroponic gardeners—can take advantage of the drainage, aeration, and non-compacting qualities of hydroton.
When mixing your next batch of soil for the garden or containers, try using up to 30% total volume of hydroton. It will greatly improve the overall structure of potting soils, enhancing root productivity. I also like to add about an inch deep of the pellets at the bottom of container planters to ensure proper drainage. You’ll never overwater with a layer of this stuff at the bottom of your planters.
Overall, hydroton truly lives up to its reputation for being magical growing rocks. These small balls of expanded clay offer benefits to all types of gardeners. Get out there and try some in your garden!
This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.
Terrence Yeoh on February 13, 2018:
Read More From Dengarden
Can I grow succulents with hydroton and soil.
Jeff on November 24, 2016:
Where does Hydroton come from
Kris Heeter from Indiana on March 22, 2012:
These rocks are great - I've used them and like their ease of use in hydroponics!
RTalloni on September 12, 2011:
So interesting to learn about hydroton pellets. Thanks for the overview!
NormaRuth from Oregon on September 06, 2011:
Very interesting. I would be interested in trying this.
Zach (author) from Colorado on September 06, 2011:
Thanks for the feedback Prisana. Hydroton rocks are definitely worth looking into as a gardener. Good luck to you in the future!
Prisana Nuechterlein from Thailand and Colorado on September 06, 2011:
I've never heard of hydroton rocks before. Very informative article and well written. I may use them in the future. Voted Up and great title. It really caught my eye.