Landscaping plans can cover a lot of ground, pun intended. There can be planting plans with details of soil mixture diagrams; sometimes the landscaping plans show the details for preventing soil erosion and sediment control; there could be plumbing diagrams for sprinklers, water features, or irrigation system. Then there could be the items Retrograde cited.
What specifically are you looking at and what do you feel comfortable reviewing? Are you reviewing the aesthetics, design drawings or shop drawings?