With cool temperatures the rate should be reduced, but frequent irrigations might necessitate an increase of fertilizer. Inadequate rates result in loss of color and may cause spotting. High potassium can cause leaf spotting and reduce color intensity. Calatheas are damaged by fluoride and the pH should be maintained near 6.5. Seven pounds of dolomite per cubic yard can be added to maintain the proper pH in most potting media.
Large plants are more susceptible to high summer temperatures.
When plants are small, they are tolerant of 100 F maximum, but when large, temperatures above 90 F will reduce quality. Calatheas are produced by divisions or tip cuttings, with nodes to form the roots. Mist and reduced light are important during the early stages of propagation. Control - Several factors may be involved including light, pH, or excess fertilizer. Maintain light levels between 1000 and 2000 ft-c and keep pH near 6.5.