These docs are for an old release. Info on upgrading to v4
edit doc

eventLimit

Limits the number of events displayed on a day. The rest will show up in a popover.

Boolean, Integer. default: false

When there are too many events, a link that looks like “+2 more” is displayed. The exact action that happens when the user clicks the link is determined by eventLimitClick.

A value of false (the default) will display all events as-is.

A value of true will limit the number of events to the height of the day cell. View a live demo.

An integer value will limit the events to a specific number of rows.

For the all-day section in the agenda views, a value of true will limit the number of events to 5. To fine-tune this, use View-Specific Options like this:

$('#calendar').fullCalendar({
  eventLimit: true, // for all non-agenda views
  views: {
    agenda: {
      eventLimit: 6 // adjust to 6 only for agendaWeek/agendaDay
    }
  }
});