Sweet Corn (Popcorn) Robust is the best variety for growing popcorn in the UK – in our opinion.  This fast maturing variety will produce large cobs packed full of corn.  Unlike sweetcorn, leave the cobs on the plants until they are very well dried, usually in October. Take the separate pieces of corn off the cob, and place in a clean paper bag. When needed, take off the individual kernels, place in a clean paper bag, microwave for about a minute, allow to cool- and enjoy your popcorn! Popcorn should be grown away from other sweet corn to avoid cross-pollination.