Why is Hindu custom to break coconut primarily related to Lord Ganesh?
There is a custom in Hinduism that any puja of any god should start with Ganesh puja first. He should be prayed first and then proceed to the other. This is done because Lord Ganesha avoids vignaas which means hurdles during our puja. His puja gives us strength and security. He satisfies for the prayer and supports through the entire puja without any hurdles. In that process we usually break coconuts as Ganesha likes coconuts so much. Not only coconuts but also jaggery, milk etc. We offer all the above and make him satisfied. But this doesn’t mean that this is a must.People who can afford can do, but for the poor it is impossible. So there is a story that in which ganesha himself said that he will get satisfied when a person offers even a single piece of grass with whole hearted belief.