The present invention relates to a process for preparing a zeolitic material having a framework type FER and having a framework structure comprising silicon, aluminum, and oxygen, said process comprising (i) preparing an aqueous synthesis mixture comprising water; a zeolitic material having a framework type other than FER and having a framework structure comprising silicon, aluminum, and oxygen; a source of silicon other than the zeolitic material having a framework type other than FER; an organic structure directing agent comprising piperidine; a source of an alkali metal; and a source of a base; (ii) subjecting the aqueous synthesis mixture prepared according to (i) to hydrothermal synthesis conditions comprising heating the synthesis mixture to a temperature in the range of from 140 to 190 °C and keeping the synthesis mixture at a temperature in this range under autogenous pressure, obtaining a mother liquor comprising a solid material which comprises the zeolitic material having a framework type FER.