PROBLEM TO BE SOLVED: To enable a user to individually install and remove each greening unit and each watering pipe when installing watering pipes for watering nursery beds, in a structure in which greening units formed by supporting the nursery beds with frame materials are mounted to mounting bases to which vertical greening devices for greening the vertical surface of a building are fixed to the vertical surface in such a manner of facing horizontally.SOLUTION: A mounting base 15 is provided at its lower part with pipe support pieces 15k and 15j having the width to house a watering pipe 18, the opposite distance of the pipe support pieces becoming narrower as nearing the lower end. The end parts of the pipe support pieces 15k and 15j form a pipe support groove 15e having an opening 15i whose opening size is smaller than the external diameter of the watering pipe 18. The watering pipes are disposed in the pipe support grooves 15e.
