Two fire engines from Fulwood and Preston were called out to the well-developed fire on Crosby Place at around 8.30pm on Thursday.
Crews arrived to find the fire had spread to nearby fence.
A Fire Service spokesman said: "Firefighters arrived to find a fire in a plastic garden shed.
"The fire had started to spread to the fence and a nearby conservatory at the property was damaged by heat.
The fire was tackled using a hose real jet."
Crews remained at the scene for 45 minutes.
Nobody was injured in the incident.