Calathea

Calatheas are native to the rainforests of Central America; thus, they require a warm, moist environment.

Temperature: Best growth comes with temperatures between 70 and 85º. Avoid temperatures above 90º or below 65º. Allow for good ventilation at higher temperatures. Keep humidity at a minimum of 60%.

Light: Light levels should be kept around 1500 to 1800 foot-candles.

Fertilization: Calatheas are sensitive to high salts. You will need good quality, low salt water. When incorporating dry fertilizer, use moderate rates. When using liquid fertilizers overhead, rinse plants briefly with plain water before and after the fertigation. An EC of 1.2 to 1.4 is sufficient. A ratio of N/P2O5/K2O of 1/0.4/1.8 is recommended. Insufficient nutrient levels will cause loss of color in the leaves.

Medium: As Calatheas should be kept moist at all times, it is important to have a well-drained mix with good quality peat or coir. The pH for roseo-picta types should be at 5.0. Others prefer 5.5 to 6.0. Fluorides can burn the tips and margins of older leaves. As these low pH levels make fluorides readily available, use low-fluoride Phosphorus and water sources.

Diseases: If kept too wet, Calatheas can get Pythium and Fusarium. High salts also cause root-rot symptoms. Leaf spot diseases such as Helminthosporium will proliferate when the foliage remains wet for extended periods. In cooler periods, botrytis can be a problem.

Pests: Watch for spider mites, thrips and mealybugs. Microscopic mites can cause necrotic lesions near the margins similar to disease or fluoride injury. Watch for occasional outbreaks of caterpillars and snails. Horticultural oils will burn the foliage of Calatheas.

This text is a recommendation only; it is not an endorsement of any products or acceptance of any liability as a result of usage.