From the parking point follow the poled route through the farmland. Be sure to stick to the trail as this early part is a crossing of private property. Normal farm rules apply: if the gate is shut- leave it shut; and if the gate is open- leave it open. The trail up the ridge line is a bit steep but well worth the effort.
The summit is 800m above the carpark so its is a nice 1/2 day blowout. DOC sign is 2 1/2 hr to summit.
Mt Barrosa became publicly accessible as a result of the tenure review process in 2010. There are wonderful 360 degree views of the plains and the Ashburton Lakes region. I especially liked the view of the side of Mt Somers.