The White Horse Canyon Trail trailhead is located off of Potrero Road, just east of the little bridge next to Vista Oaks Way. From Thousand Oaks/101 take Westlake Boulevard to Potrero Road, turn right, and the bridge is less than half a mile away. Park either in allowed spots on the opposite side of Potrero Road or in an adjacent neighborhood.
You walk into this gulley to get to the nondescript trailhead. In fact, I don't see signage that actually says White Horse Canyon Trail. But there is the following entry point that does make it clear:
The trail is really more like a fire road, wide, somewhat rocky, but not particularly difficult. The climb gets you up to some peaks that provide views of all the surrounding areas.
Wide trail. Be aware that private residences are adjacent to the first portion of the trail.You can take the White Horse Canyon Trail to the Los Robles Trail and do a 6 mile loop back the start, or you can reach the first peak at about 1,300 ft, take in the views, and turn back, for about a 2 mile hike.
There's a nice little map showing a counter-clockwise loop from White Horse to Los Robles going east, looping back to White Horse. Visit www.cosf.org/website/html/white-horse-los-robles.html.
Folks often ask me if trails are stroller friendly or not. This one in my estimation is not particularly stroller friendly because the surface is often uneven, with many loose rocks and soft dirt at times. It is do-able but not one of the better trails for that purpose...in my opinion.