To grow croton petra plants outdoors, provide ample space between each plant, and keep them warm and humid since they are tropical plants. They thrive in partial shade and medium to high water.
Croton petra plants are slow growers, but they can grow as high as 10 feet tall. Plant them 2 to 3 feet apart in an area with good drainage. While bright sun does maximize the foliage colors, too much sun can fade the leaves and even stunt their growth. Plant croton petra plants in an area that receives shifting sun. Also, water them frequently. New leaves wilt when the plant needs watering -- use that as a watering guide. Allow the soil to dry out between waterings.
To plant a croton petra, start with a 4-inch stem cutting with three to five leaves. Dip the cut end in a rooting hormone and plant it in a pot with fertilized potting soil. The cutting should be ready to plant outdoors in about one month. When planting the new cutting outside, add compost to the hole and top with peat humus.
Croton petra plants need only occasional trimming to keep their size in check. Trim the stems rather than across the leaves. Fertilize seasonally, in spring, summer and fall. Use a granular fertilizer. If the croton petra plant becomes infested with spider mites, scale insects or other parasites, wash the leaves with mild soapy water.