 They grow best in loose, highly organic potting soil, and they benefit from high nitrogen, water-soluble fertilizer once or twice a month, more often while they're outdoors in the summer. Crotons' leaf colors vary greatly, and so do their shapes. Elongated oval leaves are common, but you'll also find varieties whose leaves are as twisted as corkscrews. Some are lobed and T-shaped, and others are extremely narrow, almost grassy.