Temporary Greens are often classified as “Wrong Greens” or “GUR-No Play Zones” and so you must take relief from them if they interfere with the lie of your ball, your stance, or area of intended swing (Rule 13.1f). You go to the nearest point of complete relief (i.e. lie, stance and swing not touching the green) which is in the general area and not nearer the hole. Your relief area is within one club length of, and not nearer the hole than, this point. (Check your local “winter” rules to understand the status of temporary greens which are not in play at your course).
Even with the “pick and place” winter rules (Model Local Rule E-3) in place you must still drop the ball into the relief area first – having done this correctly you may then use the “pick and place” Local Rule if you are allowed to do so.