|'Slate Sweet', also known as 'Black Mexican' and 'Black Sugar', is an heirloom variety, possibly the most popular hairloom corn grown today. It matures in 75 to 80 days. The plants grow 6 feet and bear 6 to 8 inch cobs about 1.5 inches in diameter. The kernels are black, on a white cob. The corn can be harvested early and eaten as sweet corn, or harvested late, after the kernels change to blue and black, for flour. Originally domesticated by Mesoamericans, it is a staple food with many other traditional uses. Home gardeners love to grow corn, and there are many varieties suited to different climates. Plant seeds 1 inch deep in rows or clumps, two weeks after the last frost date. Corn needs rich soil, full sun and adequate moisture to produce good ears. It is wind pollinated, so if you want to save seed, you will need to either stagger the planting time of different varieties, or plant them 1/4 mile apart. Water deeply.