Sie pflanzt die Küchenkräuter in _____ Garten.
Should "den" or "dem" go into the blank? It is not clear to me whether "planting" counts as moving into the garden (i.e. would use "den") or as static action (i.e. would use "dem").
Both solutions are correct, but they have different meanings. It depends on what you want to say:
She is in the garden and there she is planting herbs. Maybe she is planting them into little pots, or into the ground. You don't know into what she is planting them. You know just that she is in the garden while she is doing this:
This is correct, but better is to put "in" and "dem" together to "im" ("im" = "in dem"):
You can ask for this with "wo" (where):
In other languages you would use a case called "ablative" to describe where something is located. But German has no ablative, so the ablative function must be executed by an other case, which in german is called "Dativ" ("dative" in engl). German Dativ gets it ablative function by:
You have the information that she is planting the herbs into (not just in) the garden:
You can ask for this with "wohin" (where to):