On 15/01/2013 23:30, Janet Tweedy wrote:
On 15/01/2013 15:12, Janet wrote:
Any weed requires photosynthesis to sustain rootsystem survival; and
if you keep preventing photosynthesis (by ruthlessly destroying all new
growth) the roots eventually become too weak to sprout again, and die.
I've even killed an ancient dense plantation of japanese knotweed by
that method (it took a couple of years).

A combination of chemical weapons and physical removal is the best bet
and glyphosate is the method of choice against pernicious weeds. The
bits you miss are less likely to regrow after a dose of glyphosate.

So how does grass grow back so well if we constantly cut it back so hard
in our lawns?

It doesn't if you completely scalp it often enough. Grass is designed to
be grazed by animals and has silica in its leaves to wear out their
teeth. It lacks more sophisticated chemical weapons and has evolved a
coping mechanism that involves being eaten since it cannot run away!

So long as you leave an inch or two the grass is still happy just keep
shorter and less able to flower. Left to its own devices it would reach
a certain height and then flower and set seed like all flowering plants.

--
Regards,
Martin Brown