Where im at, if I didn't mow until June my lawn would be three feet tall and i'd have several tickets. Still, I don't mow until may, and then just the front for another few weeks.

You want biodiversity? Don't weed, don't spread any pesticides or growth chemicals, and don't let the natural grass go so long it chokes out the other plants. And the real key, is don't do any of those things for years. From the street, my yard looks like a yard. It's a different color than the neighbors, but it's still green. Up close, it's a salad. More violets, Moss, clover, flowers, wild lettuce, and a hundred things I can't identify than grass. Its full of bees, caterpillars, beetles, butterflies, and stick bugs.

I got my neighbor on board, and we're single handedly keeping fireflies alive in the city. I started seeing bugs I haven't seen since I was a kid.

As an added bonus, since it's a smaller proportion grass, I don't have to mow half as often to keep it looking 'nice'.

I'm not an ecologist, but I feel like it's a solid step in the right direction.