Sage agasthiar has prescribed particular flowers for offering to nine planets which governs the world for the use of people to get relief from problems in their life.
Sun - One should offer Senthamarai flower or light lamp using lotus petal on sundays for sun as it will give relief from eye problems and problems related to job.
Moon - One should offer alli flower in white colour or should make kumkum archanai for moon on mondays as it will give relief from water related problems, remove obstacles while going for a foreign country and get relief from legal issues related to women.
Mars - One should offer senbagam flower for mars or for lord muruga on tuesdays as it will give relief from problems related to health, will give victory in competitions.
Mercury - One should offer venkanthal flower for mercury on wednesdays for getting relief from court cases, skin problems, business losses.
Guru : One should offer mullai flower for guru on thursdays as it will give a prosperous life.
Sukkiran : One should offer white lotus flower for venus on fridays as it will give good married life.
Saturn : One should offer karunkuvalai flower for saturn on saturdays as it will give a relief from problems caused by saturn.
Rahu : One should offer mantharai flower for rahu as it will give relief from various problems caused by rahu.
Ketu : One should offer sevvalli flower for ketu as it will give relief from problems caused by ketu.
Thanks to sithan arul blog.