I honestly have no idea, but I know it only spawns in the glass desert in some sites and only 2 of them a day, but say you were running around the glass desert and happen to get to a place that was growing some gilded ginger
Hard to actually calculate the probability in this case given just how many factors there are to account for. Route and time are important factors but as is volume and such for determining just how precise it is to randomly locate one. If ignoring any actual practice to the situation your odds of finding one are roughly something like 2%. This though is extremely, and i mean extremely, misleading as it ignores literally the structure of the glass desert, the actual probability of coming across any particular node and so forth. The only thing this is remotely accurate for is the odds of a ginger being in any 1 particular node.