Calendar olederThanTwo = Calendar.getInstance() - 2_weks;
select creationDate < olederThanTwo;

@Entity
class Persistent {

    @Column
    private Calendar creationDate;

}

List<Persistent> getOlderThan(Calendar calendar) {
    session.createCriteria(Persistent.class);
    session.add(Restrictions.lt("creationDate", calendar));
    return session.list();
}

Calendar twoWeeksBefore = ...;

List<Persistent> result = getOlderThan(twoWeeksBefore);