Lots of Factors
Also depends significantly on locality/region. I suspect
that irrigation would also play a part. But sward species
would probably be a very big factor along with local
natural precipitation rates and growing conditions and
if irrigation is available/manual/automated.
I concur with the observation that the thicker the
lawn, the less weed invasion. And that thickness is
very often a factor of cutting height. Too many
people scalp their lawns to death.
Last October (2011) I sowed a large area in a new
type of dwarfing rye grass (lolium perenne) blend.
It was a big project; the pond is still not finished.
From this:
To this:
The irrigation is essential, as the area is an old river
bed - a mix of stones and silt. By hand, I removed
two tons of stones from the surface, after machine
preparation was over. Back breaking and tedious!
It's thickened up well and does have the much finer
leaf blade that the dwarf species promised. So far,
I suspect it's not as prolific a grower as the standard
pasture cultivars are. And thank goodness for that!
I'm not producing cows, here.
My cutting height is around 25mm (1") or a little
higher. The area has an automated Hunter pop-
up irrigation system installed.
Anything in the order of 50 mm (2") or more, in
New Zealand, would be bordering on a pasture
field, rather than a back or front yard lawn.
Horses for courses, it seems . . .