"lbbs" wrote in message
...
Does it matter on the order you do it. Also, what time of the year
to do
it?

Depends on where you live and what kind of turf. Warm season
Bermudagrasses, for example, are usually dethatched in the spring after
the grass is growing good to give it a chance to recover - sometimes
also in the fall before it goes dormant. If overseeding with ryegrass
for the winter, Bermuda lawns are dethatched just before sowing the
ryegrass, than again in the spring to kill off the ryegrass to encourage
the Bermuda. -Olin