High winds and the actual material being burned made it difficult for firefighters to extinguish the flames.
"It takes not only water, but also heavy equipment to tear these piles apart and actually get down to the seat of the fire," Ontario Fire Deputy Chief Mike Pelletier said.
The blaze began at about 9:14 p.m. Saturday near Grove and Chino avenues and burned until Sunday afternoon.
Firefighters contained the flames to the property. About 3 to 5 acres of products were burned.
Several small structures were damaged, including a shed and hay barn. No injuries were reported.
No evacuations have been ordered, but Grove and Chino avenues remained closed.
The cause of the fire was under investigation.