The ornamental design for an indoor plantcultivator, as shown and described.
FIG. 1 is a front perspective view of the indoor plant cultivator showing our new design;
FIG. 2 is a front view thereof;
FIG. 3 is a back view thereof;
FIG. 4 is a left view thereof;
FIG. 5 is a right view thereof;
FIG. 6 is a top view thereof where the bottom view is a mirror image; and,
FIG. 7 is a reference view showing the use state in which the shelf is slid forward.
The broken lines depict portions of the indoor plant cultivator that form no part of the claimed design. The dash-dot broken lines define the bounds of the claimed design and form no part thereof.