At what height should I be mowing my lawn?

Goeie more mense,

Well the Height Of Cut (HOC) varies based on grass species etc, and it's not set in stone. For example, Kikuyu is comfortable at 30mm but I mow mine at 10-20mm.  I just have to work a little harder to keep it there.  Some mow there kikuyu at much longer lengths, and that's also fine...if you prefer a bush for lawn.  In my books, too short is a problem and too long is also a problem. So, what's the best HOC for your species without causing the lawn to look ugly with only a weekly mow?

Here is my advice:
Kikuyu - 30mm
Cynodon Dactylon (Bermuda/kweek) - 25mm
Buffalo - 50mm
LM Berea - 50mm
Perennial Rygrass - 25mm
Kentucky Bluegrass - 25mm
Tall Fescue - 70mm 

In ideal circumstances, you should have planted the correct grass for your region and specific environment. For example, kikuyu doesn't handle the shade as well as LM Berea does. Additionally, a grass species such as Ryegrass will not handle the sever heat of Vioolsdrif for example. 

Some do's and dont's:
Do mow your lawn more often than not.
Do make sure that your mower blades are always sharp.
Do make sure that you clean your mower regularly.
Do make sure that your grass is dry before mowing.

Don't take mow more than one third of the leaf off in a single session. 
Don't mow when the grass is stressed, such as during adverse weather conditions.
Don't mow when your grass has a disease. Treat it first.
Don't scalp your lawn without being prepared for what's needed thereafter.
Don't mow too short when your grass is in the shade.

I hope this helps you get a better understanding of your lawn requirements. I am also aware that some of you might not even know what grass species you have, so reading this is useless in the first place.  If you're one of those, simply email me and I will identify your species for you.