Six fire engines and around 40 firefighters were called to reports of a fire in the undergrowth on Lauders Lane in Rainham in the early hours of Tuesday morning.
Around five hectares of disused landfill and grassland was damaged by fire. There were no reports of any injuries.
A London Fire Brigade spokesperson said: "Firefighters worked throughout the night and into the afternoon to bring the fire under control.
"The hot weather we have been having makes the ground extremely dry, which can cause grassland like this to burn quickly when exposed to even the smallest of sparks.
"A common way that these fires start is from glass bottles or other broken glass which can concentrate sun rays onto dry grass and shrubbery. Clear away bottles, glasses and any broken glass to avoid them magnifying the sun and starting a fire.”
The Brigade was called at 0030 and the fire was under control by 1224 (Tuesday). Fire crews from Wennington, Dagenham and Barking fire stations attended the scene.
The cause of the fire is under investigation.
Brigade top tips on grass fires: