In Florida, the police are generally not allowed to enter a person’s home to search or investigate a crime without permission from the homeowner or a valid search warrant. In some cases, the police cannot even go onto your property to search or investigate if the property is properly fenced and it is clear people are not welcome on the property. The right to privacy in one’s home is one of the strongest constitutional protections.
However, for homes that are not adequately fenced in, the police are normally allowed to go up to anyone’s door, knock and ask questions. As long as it appears that the general public would be allowed to go up to a door and knock, the police can too. The residents can refuse to answer the door or they can refuse to answer any questions if they do open the door, but the police are welcome to try and knock and see if they can get someone to talk or even let them in. If the residents do not cooperate, the police are not allowed to take the encounter any further, at least according to the law. In practice, the police do not like to take no for an answer and may act accordingly.
In any case, if homeowners or other residents do not want the public or the police to be able to just walk up to their doors, knock and try to get information, they need to make it clear that their property is not open to the general public. Fences and gates work well to do this. Signs can as well, but the sign needs to be clear. There was a case in Jacksonville, Florida where a person growing marijuana in his house had a “No Solicitors” sign on his door. He had no gate or fence and no other signs. The police walked up to his front door, knocked, smelled marijuana when the door was opened and subsequently obtained a search warrant. The homeowner was arrested for growing marijuana.