Growth of Hibiscus in Media Amended with a Ceramic Diatomaceous Earth Granule and Treated with a Kelp Extract

Abstract

Growth of Hibiscus rosasinensis L. `President' under daily irrigation and decreasing irrigation frequency was compared in a 5 pine bark : 4 sedge peat : 1 sand (by volume) medium amended further with 0%, 10%, 20%, or 30% (by volume) Axis, a kiln-fired diatomaceous earth granule. Half of each substrate treatment also was drenched three times with Agroroots, a kelp extract. Shoot and root dry weights were compared after 4.5 months of growth. Container media amended with Axis at 10% volume yielded hibiscus plants with higher shoot dry weights than nonamended media. Root-zone drenches with Agroroots increased shoot dry weights of plants subjected to decreasing irrigation frequency and grown without Axis, but did not significantly affect plants receiving daily irrigation. Shelf-life effects of Axis treatment revealed that all plants reached the permanent wilting point 5 days after cessation of daily irrigation. Both products may allow container plant production with less irrigation. Further tests should be conducted with a broader range of species.