Start by making the planter lighter. Remove plants if possible, scoop out soil into buckets or a tarp, and take out loose gravel or inserts. A heavy urban planter box is much easier to control when it is half empty, and you reduce the risk of a sudden slide that can gouge the floor.
Clear and protect the route. Sweep the floor so grit does not act like sandpaper. Measure doorways and turns, then lay down rigid protection such as plywood, hardboard, or interlocking floor mats. Avoid using only towels or blankets; they can bunch up and trap dirt. For hardwood, use hardboard over a clean floor. For tile, use plywood to spread the load.
Use the right moving tools. Furniture sliders rated for the planter’s weight are the simplest option. With a helper, tilt the planter just enough to slide a slider under each corner or foot. Never tip it far enough to crack the planter or spill leftover soil. If you do not have sliders, place the planter on a sturdy piece of plywood and slide the board. A furniture dolly with pneumatic wheels works well for longer moves, especially over thresholds.
Lift with leverage, not your back. For a very heavy box, use a pry bar and wooden blocks to raise one side a little at a time, then insert sliders or blocks. Keep your hands clear and wear gloves. If the planter must be carried, use lifting straps and two people, and lift with your legs. Push from the base rather than pulling from the top; pulling can tip the planter and scratch the floor.
Move slowly and avoid pivoting. Have one person guide the front and another watch the back. Take doors off their hinges if needed, and use a threshold ramp for small lips. Do not drag the planter across the floor, even for a few inches. Once it is in place, remove the sliders or board, clean the floor, and check for grit or small scratches. A little preparation protects both your floors and your planter.