How much sun does your lawn get each day?

How much water does the lawn get from rain? Can you water when there isn't enough rain?

How often do you want to fertilize and how often do you want to mow?

Where are you? Zone 8 doesn't tell us much. It only tells us how cold it gets at the coldest. Most people think zone 8 means hot, since states like Texas, Alabama, Mississipi, Georgia, the Carolinas are mostly zone 8. But So is much of the western part of Washington state.

Another piece is the type of grass you are growing...
Some grasses have a natural apple green color (Like Centipede) and others like Bluegrass can get a darker green color when they are happy....

Next is culture... Your particular grass may *Have* the potential to be very dark green... but the culture it gets may not be conducive to this.... Amending your soil based on a soil test will help sort a whole lot of this out.

One thing that helped my grass based on a soil test was iron. I supplemented my fertilizer with Milorganite at full bag rate -- but others here have suggested that foliar sprays are more effective for Iron...

A foliar spray would also have a benefit of not producing a giant flush of green top growth in the heat of Summer that leads to fungus outbreaks.....

But.. base it off of a soil test...