No, lease agreements do not need to be notarized in Delaware. Some states require residential leases to be notarized based on the duration of the lease, but Delaware is not one of them. If the lease meets the requirements to be binding, it does not need to be notarized.
The landlord and tenant can agree to have the lease notarized if they wish, but it is not required by law in order for the lease to be enforceable.
The information for this answer was found on our Delaware Residential Lease Agreement answers.