“Suddenly he saw something protruding from the ground, and he realized that it is some sort of a shell,” said police spokeswoman Ewa-Gun Westford to Sveriges Radio (SR).
The man quickly alerted the authorities and according to the police the explosive device is deemed to be of the 50 kilogrammes calibre.
“We think that it is live and that is also the information we have received from the military so we will work from that,” said Westford.
Police have set up an incident control centre in the area, with some 30 officers at the scene, to evacuate an area within a 900 metres radius of the explosive device and keep residents informed of what is going on.
When all the residents have been brought to safety, the military bomb group will free the bomb from the ground, and it will then be removed so that experts can disarm or blow up the device under controlled conditions.
The nearby highway Riksväg 9, between Skateholm and Hörte, will also remain closed until the device has been moved.
Police have no idea where the shell comes from and how long it has been in the earth beneath the private garden.
"It could be as old as dating back from the First World War," said Mia Sandgren, of the Skåne county police, to daily Dagens Nyheter.
What is unusual is that the device was found in a private garden and not near the coast or on a beach, according to Sandgren.