Hartlepool Borough Council allotment amnesty declared
Unauthorised allotment gardeners in Hartlepool have until the end of March to register or face eviction.
About 30 people have already come forward under the amnesty, but council officials believe a "significant" number of unregistered gardeners continue to work plots in the town.
Hartlepool Borough Council said it was cracking down on illegal sub-lets or sales of plots.
The authority said it needed to know who was responsible for each allotment.
Environmental projects officer Kate Ainger said: "It is important that our records are up to date so if an issue arises involving a particular allotment we know who we are dealing with and are able to contact them."