Ten fire engines and around 70 firefighters were called to a fire at an area of allotments and sheds on Stanley Road, Hounslow.
The allotments and sheds were destroyed by fire. A disused builders' warehouse was also destroyed in the blaze. Firefighters removed 24 gas cylinders and cooled them to ambient temperature as cylinders can explode when exposed to heat.
Around 50 people were evacuated from neighbouring properties as a precaution.
One woman was treated for smoke inhalation and was taken to hospital by London Ambulance Service crews.
A London Fire Brigade spokesperson said: “Despite the recent rain, we are still attending a large number of grass fires across London. We’re asking the public to take care not to drop cigarettes or matches on dry grass and to keep a very close eye on barbecues. Dropped glass can also start fires as the sun can magnify the sun’s rays. Grass fires can quickly spread and cause serious damage, so if you see grass smouldering, please call 999 immediately.”
The Brigade was called at 1530 and the fire was under control at 2122. Fire crews from Feltham, Twickenham, Chiswick and other surrounding fire stations attended the scene.
The cause of the fire is under investigation.