FIRST OF ALL FIND ANY BUGS ON IT OR NOT ,IF ANY CURE IT USING PESTISIDE. * I THINK U HAVE TO REPOTTING PLANT, ALSO PROVIDE SOME ORGANIC SOLUBLE FERTILIZERS.MAKE SAND MIXTURE IN WHICH CAN PLANT ROOT SYSTEM CAN BREATH WELL BY USING 'COCOPIT'. * PUT YR PLANT IN MEDIUM LIGHT. MORE WATERING ALSO CAUSE DECAYING OF ROOTS IT AFFECTS DROPPING LEAVES (IN THIS CONDITION FUNGISIDE SHOULD BE APPLICABLE). THESE ANS.IS NOT SUITABLE TELL ME PROBLEM IN DETAIL.

Dear Friend, it could be that your plant is dropping it'sleave because it sits in a drafty area? I know mine did much better after I put it in a room with less air movement esp. cold air and the plant did so much better. Croton do not like cool drafts they will drop all their lower leaves. Hope this hint might help you.