Hello James
If the landscape strip is indeed that , and there is not a walkway there next to the drop-off .. then I would say that no guardrail would be needed .. This not being designed as a place where people would be walking or assembling ..
If it is a place that people would be normally congregating or walking .. then it would need a railing if it werwe over 3 feet between levels

Here is what I could find ..

A guardrail is required by code section 1003.2.12 of the IBC and section R316 of the RBC. These code sectionsalso list the requirements for guardrail systems.

Guards are required along open sided walking surfaces that are located more than 30" above a floor or grade below.

There are some exceptions to this rule though. These exceptions are for loading docks and stages such as those found in auditoriums. The minimum height requirement in the IBC for guardrails is 42" measured vertically above the nose of the tread of the steps. The RBC allows theguardrail system to be 36"high in residential construction. A guardrail used in a residence along the open side ofa stair system allows a minimum of 34" high when measured vertically from the nose of the treads. Guardrailsmust be constructed in such a manner so that a 4" diameter sphere can not pass thru any opening within theguardrail system. One exception to this rule allows an opening of 6" in the triangular opening formed by the riserand tread in an open-sided stair system

OK .. I messed up .. that was 200 IBC .. the 2006 property maintenance code has the same language in ... Section 306 - Handrails and Guardrails, 2006 International Property Maintenance Code: Every exterior and interior flight of stairs having more than four risers shall have a handrail on one side of the stair and evry open portion of a stair, landing, balcony, porch, deck, ramp or other walking surface which is more than 30 inches above the floor or grade below shall have guards. Hnadrails shall not be less than 30 inches high or more than 42 inches high measured vertically above the nosing of the tread or above the finished floor of the landing or walking surfaces. Guards shall not be less than 30 inches high above the floor of the landing, balcony, porch, deck or ramp or other walking surface. I will look further