Q: In my work as a landscape designer, I’m challenged by the different kinds of shade on a site. Shade under a maple tree is completely different from shade on the north side of a house. But both are considered “full shade”. Do you know of a light meter that can be used to figure out how much sun a site gets?

A: This is a question I face all the time! Lawn grass companies claim some varieties will grow in dense shade but no definition of shade is given. I’m positive grass will not grow on the north side of a house where no sun ever strikes the ground. Complicating matters is that the light our eyes can see is not the same light that plants use. Plants need a certain quality and quantity of specific wavelengths of light to photosynthesize effectively. For a good explanation of light in the landscape and sources of light meters, see xrl.us/lightmeasure