Personally I look at how rough the ground is first, then how tall it is and what kind of grass. Really tall and thick stemmed stuff I stay away from. I won't mow over rough ground even though most commercial mowers would probably be ok but for me it's not worth it. If in doubt don't do it.

If i only mowed lawns less than 5" I would lose all my biweekly accounts.

 

As long as it's just grass and it's not a foot high you're fine. You need to know that there isn't stuff under the grass though that will damage your mower. (rocks, sticks, etc.)

 

You wouldn't want to put a bush hog on a lawn just because it's over grown. Cut it down to size and clean up the mess. If it's a hay field then treat it that way.

 

I have a client that got sick last fall and did not care for their lawn since. It is a nice 1.7ac property, just tall grass and lots of sticks needing cleaned up. For the initial cleanup mow I made 2 passes with a bushog pretty much everything but the front yard(was sparse) then used a super z to make 2 passes finally ending up at 3.25" and pretty good clipping dispersal... for what it was.

That grass was 16"+ and thick in the back. Without the bushog I would have passed on this one which has become a lucrative weekly mow. Every tool has its use.

 

I use my Predator Pro like a bush hog on my own property. A 2 acre unused pasture gets mowed 4 or 5 times a year. I pick a dry stretch and mow in the afternoon when there is no dew, usually with mower deck in transport position. My Kawasaki DFI goes through the knee high and higher weeds fine going slow and it takes me about 90 minutes to do the 2 acres. The worst damage I've done is bent a deck baffle on a tree stump.

My tenants and neighbors next door at the Sportsdrome

 

I use my Toro 6000 as much as possible on my horse farm including cutting pastures. Last year with all the rain in KY I needed to bush hog as I could not keep up. I have miles of horse fence and trails, you can cut under the fences with the Z but not the bush hog. If your Z can cut it, usually up to a foot, use it. If not bushog it.

 

We have a client with an area in her backyard that's only mowed twice a year, when I cut it I make the first pass with the deck on a Lazer Z in the transport position.

 

Flail mower is what you need. A flail mower will eat up the tall grass, distribute everything evenly, and the cut quality is much better than a bush hog. They don't like anything woody, though.

A flail mower can take foot-tall grass and have it looking better than most people's front yard in one pass.

 

If I did not know the ground and the grass was so high I could not see potential problems, then I would not use a ZTR. You could rent a brush hog to chop it down and determine if its safe for your finish mower. Besides rocks and roots we were always concerned with rope or wire getting wrapped up on the blades.