The labeling set, tape and pen

A combo that won't fail - strong tape that won't come off and a marker pen with ink that won't fade.
 
White PVC insulating tape, 19 mm x 20 m, with a matte finish that is suitable for labeling plant pots.  Strong adhesive so the label does not come off even if pots are left outside for years.
 
Sakura marker pen with two tips in different widths.