I recently found a wet ceiling tile in my basement after 3 days of rain. There is no plumbing over it or a signs of any wet joists, floors, or drywall even though it is right next to the wall. I am thinking it may be water getting in from the foundation wall. I also suspect it is because of the flower gardens that are all along the house. My question is what is the best method of diverting the water from the foundation. I am willing to fill in the garden and create a slope but what sort of soil should I use (or rock for that matter). Is flashing stuck to the concrete also recommended?

here is a picture of one of the garden in question...