Kivy: Trigger Method or Function on Entering a Screen

Use on_enter: in your .kv file

<ShowGardenScreen>:
    on_enter: root.populate_info()

In this case, my root.populate_info() refers to a method in the ShowGardenScreen class within my .py file. It searches a database and then feeds all the information about that specific function to the Labels and Buttons within that screen. Here is the above in context:

<ShowGardenScreen>:
    name: "show_garden_screen"
    on_enter: root.populate_info()
    GridLayout:
        cols: 1
        padding: 10, 10
        Label:
            id: current_garden_name
            text: "Garden Name"
            font_size: "30sp"
            size_hint: 0.25, 0.25
        Label:
            text: "Notes:"
            font_size: "25sp"
            size_hint: 0.1, 0.1
        Label:
            id: notes_for_this_garden
            text: "garden notes"
            font_size: "20sp"
            size_hint: 0.2, 0.2
        RecycleView:
            id: plants_list
            data: []
            viewclass: "RecycleButton"
            RecycleBoxLayout:
                default_size: None, dp(60)
                default_size_hint: 1, None
                size_hint_y: None
                height: self.minimum_height
                orientation: 'vertical'
        GridLayout:
            cols: 2
            padding: 10, 10
            size_hint: 0.25, 0.25
            Button:
                text: "Home"
                on_press:
                    root.manager.transition.direction = "right"
                    root.manager.current = "home_screen"
            Button:
                text: "Search Plants"
                on_press:
                    root.manager.current = "search_plants_screen"