Sheds and a greenhouse were destroyed as fire swept through a Hartlepool allotment.
Firefighters from Stranton fire station were called to the allotments in Brierton Lane shortly before 11.20pm on Saturday night and spent two hours tackling the fire.
A spokesman said the blaze was being treated as accidental, but allotment holder Alan Brown believes it was started deliberately.
"Nobody was up there at that time of night," he said.
"it has been there for 30-off years and it is only the second time we have had a fire - we have been broken into a couple of times.
"Someone has set light to it."
A Cleveland Police spokeswoman confirmed the fire had been reported to the force and officers were waiting to speak to Mr Brown.