Scary Grass

Every Spring my husband and I have an argument about the lawn, which tends to be full of moss and weeds but is a lovely shade of green.  I say just leave it as it is, but he insists it needs "treatment".  

He always wins, as he is Head Gardener, so the grass gets a dose of 4-in-1 (whatever that is!), followed by scarifying to get rid of the dead moss etc.  For several weeks it looks like this - scary grass!!  Eventually it will grow and green up, but I'm really not convinced this rough treatment makes the slightest difference.

How does your lawn grow?