Here's our database entry for
Croton (Codiaeum variegatum 'Petra')
Croton's (Codiaeum) are indeed common landscape plants here in Florida. I've grown many Croton's in containers over the years and still have at least one in a pot but they remain outside all year round where they get many hours of high sunlight and good air circulation.
Even though conditions indoors are not conducive to the health and longevity of a Croton, they are often sold as houseplants. I guess if one can offer the ideal situation of warmth, high sunlight and air circulation, they could survive.
Hopefully someone who does successfully grow these indoors will be able to offer suggestions but I really think the issue with your little Croton is lack of sufficient light and possibly too much water. You can try placing it outdoors in full sun for a few hours each day (the longer the better) during the warm months of the year; just be sure to move it to that location gradually so as not to cause excessive, sudden stress.