In mid to late August cobnuts are picked in their green, crunchy state. Once picked they are best treated as fresh produce and kept in a fridge using a well ventilated container. Alternatively they can be stored in cool dry place in a perforated container or basket. They should be turned or shaken each day to prevent them from sweating and becoming mouldy.
Over the next few weeks the husks of the nuts on the trees will gradually change colour from green to brown (but once picked, green nuts do not ripen any more) and will have developed its real nutty flavour. At this stage the husk can easily be removed from the shell and the nuts stored in a cool, dry, place with good ventilation. Turn or shake them every couple of weeks. Cobnuts, when ripe, have a long shelf life and if stored carefully will easily last for several months.