Rice Hulls in the Mix

Rice hulls, a by-product of grain processing, are being studied for their usefulness in potting media as an alternative to perlite.  Perlite is a non-renewable mineral which is mined mainly in Greece, Turkey, the U.S. and China.  Switching to a waste product like rice hulls is more sustainable and could bring down the cost of media.

Media with perlite (left) & rice hulls (right)

Vinca grown in Sphagnum peat-based substrate with 30% perlite (left) and 30% PBH brand rice hull (right). Photo courtesy of Riceland Foods, Inc.

Some consumers object to perlite because it floats to the top of containers and looks unsightly.  Also it may be mistaken for a synthetic product such as styrofoam.

From a production standpoint, rice hulls are considerably less dusty than perlite and the color blends well with other ingredients in the mix. With a high lignin content rice hulls are slow to decompose and, similar to perlite, provide good drainage and water holding capacity.  Both materials are suitable for organic production.

Science Daily reports that Perdue University has addressed concerns that this plant-based material would absorb growth regulators as is the case with pine bark.  According to Roberto Lopez, a Purdue assistant professor of horticulture, testing showed that there were no differences in plants grown with rice hulls compared to perlite.  See the article at http://bit.ly/bHW5CI.

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About Kathy

Program Assistant with UF/IFAS Manatee County Extension Service, specializing in Integrated Pest Management for ornamental nurseries.
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