The animal welfare charity was contacted on Thursday 14 June by a member of the public who had made the unusual discovery.
Reptile experts at the charity and now caring for the large snake until the owners can be located or a new home can be found.
RSPCA exotics officer Phil Hamilton, who rescued the snake, said: “If anyone thinks they may know who this snake belongs to then we would urge them to get in touch with us by calling our inspectorate appeal line on 0300 123 8018.
“It’s hard to know for sure how this snake came to be in the allotment but it must have been a surprise to find an 8ft Boa constrictor in amongst the garden tools.
“The snake may have escaped from a vivarium or may have been abandoned. Sadly the snake isn’t microchipped so we do not know where they may have come from.
“Snakes aren’t able to produce their own body heat and as a boa constrictor is not native to this country this snake would require a heated environment with the correct temperature range for the species for the snake to stay healthy and carry out normal behaviour. Being outdoors in the UK could potentially be really serious as their body can’t function normally if they become too cold.
“The RSPCA has seen a growing number of reptiles - including snakes - being abandoned, which is thought to be because they are too much of a commitment for some people.
“Many people do not realise what they are taking on when they buy these pets so we are urging prospective buyers to do their research before getting one. We are seeing a worrying number of boa constrictors coming into our centres, because owners are no longer able to care for them.
“Although these beautiful animals may look quite hardy, snakes kept as pets are actually completely dependent on their owners they need them to provide them with the correct accommodation, heating, lighting and food, all of which must replicate their wild habitat as closely as possible to keep them healthy and allow them to carry out their natural behaviour.
“Without proper care they can suffer from serious diseases, dehydration, injuries, parasites, and in severe cases or if left untreated, they can eventually die.
"Sadly the RSPCA is experiencing widespread neglect of reptiles and we are finding more and more are coming into our care.
“The main thing we want to stress to people who are thinking about bringing an exotic pet into their family is to research the needs of the animal thoroughly and make sure that you can provide everything that animal needs for the animal’s entire life.”
The RSPCA currently has dozens of reptiles in its care looking for new but knowledgeable homes. For more information on rehoming reptiles visit