Florida is a Closed Primary State

What does this mean? This means that only registered Republicans may vote for Republican candidates and only registered Democrats may vote for Democratic candidates in a primary election. Registered voters with no party affiliation or with minor party affiliation are not eligible to vote for Republican or Democratic candidates, except in a Universal Primary Contest.

Universal Primary

If all candidates in a primary race have the same party affiliation and the winner will have no opposition in the general election, all qualified electors, regardless of party affiliation, may vote in the primary election for that office. This is called a universal primary contest. Note: Party changes must be made by the 29th day before an election.