I run a lawn service but don't do any fertilization because I'm not licensed and I don't know too much about it. I have a customer who wants me to cut on the condition that I give him some very basic fert advice, then he'll apply it himself. He said he has a zoysia lawn that is brown for most of the season (common for NJ zoysia lawns). For this type of grass in a medium shade environment, what would be some good fert to put down at this time of year? Don't have time for a soil test or anything, just something that will a generally good effect even if it's not a dramatic difference.