The ornamental design for a mailbox-mounted holder for potted plants, as shown and described.
FIG. 1 is a perspective view of a mailbox-mounted holder for potted plants
on a reduced scale according to my new design, with a mailbox and a potted
plant being shown in phantom lines only for environmental purposes and
forming no part of this design;
FIG. 2 is an enlarged top plan view of FIG. 1;
FIG. 3 is an end elevational view of FIG. 2, both end views being
identical;
FIG. 4 is a side elevational view of FIG. 2, both side views being
identical; and,