Soil Requirement: Plant your croton outdoors in a location with well-drained, humus-rich soil. For indoor growing, use a large container with unobstructed holes in the bottom and a commercial potting soil designed to provide good drainage. Add a layer of gravel to the bottom of the pot to improve drainage even more.
Lighting Needs: Place your croton where it will receive six to eight hours of bright, unfiltered sunlight each day. Provide shade from direct summer sun during the hottest part of the day.
Temperature Demands: Maintain a consistent temperature between 60 and 85 degrees Fahrenheit. Outdoors, avoid low spots that may become very cool on winter evenings. Move container-grown plants indoors when the temperature becomes too high or too low.
Watering Frequency: Irrigate moderately and infrequently, allowing the soil to dry out between waterings. Water about once per week for outdoor plants. During the winter, water less often, keeping soil moist but not wet. Spray the leaves of indoor plants with lukewarm water once per day.
Fertilizer Obligations: Fertilize your croton about once per week with a 3-1-2 liquid fertilizer, or less frequently using a slow-release form. If the plant seems to be stunted or suffering from a nutritional deficiency, increase fertilizer quantities slowly, since too much can cause the leaf colors to become dull.
Diseases to Watch For: Croton petra plants are susceptible to the bacterial diseases crown gall and xanthomonas leaf spot, and the fungal diseases anthracnose and stem gall and canker. Both crown gall and stem gall and canker present with swelling on the plant’s stems, leaf veins and roots and require the pruning of all infected parts in order to be controlled. Xanthomonas leaf spot is identified through the dark brown and black lesions that appear on the leaves. A copper containing bactericide can be used preventatively, but once the plant is infected, it will need to be eliminated. If your plant has anthracnose, you’ll notice water spots that turn tan and sometimes have black dots in the center. Treatment involves applying a copper-based fungicide and then removing all infected plants if the fungicide isn’t effective.
Common Pests: Gardeners are also going to need to keep an eye out for the following pests: fungus gnats, mealybugs, mites, scales, shore flies, thrips and whiteflies. Each of these insects is tiny and may require a magnifying glass to spot. Fortunately, pesticides, when applied using proper safety precautions and following the directions on the product label, are extremely effective against the insects.