From ThisOldHouse.com…..
Unless you live in the middle of a golf course, your lawn is likely to be somewhat sun deprived—indeed, as much as 25 percent of it is no doubt shaded to some degree, according to The Lawn Institute.
Trying and failing to grow grass in these areas is a common frustration for homeowners, since after all, sunlight is key to photosynthesis, the process that triggers plant growth. Fortunately, some photosynthesis-efficient grass species do just fine in partial sun.
It takes more than the right seed, however, to successfully grow grass in low light locations.