Corn is a heavy feeder, so add manure or compost, and use 500g (1 lb) of complete organic fertilizer per 6m (60′) of row, mixing it thoroughly into the soil beneath each seed furrow. Thin to at least 20-25cm (8-10″) apart in the row. Large eared and double-eared varieties need to be 30cm (24″) apart. Keep free of weeds until knee-high, and then leave it alone. Use the days to maturity listed for comparative purposes among the varieties only – every garden may be different.