Three fire engines from Cudworth, Barnsley and Tankersley stations were called to an allotment fire at 4am on Tuesday morning in Stairfoot, Barnsley.
When crews arrived at the Hunningley allotments they found six small buildings on fire.
Firefighters used two main jets and a hose reel to bring the blaze under control.
Initial investigations believe the fire was started deliberately.
Crews left the scene at 6am.