Germinating seed before sowing. This is always done for potatoes, and may also be done for other seeds, such as sweetcorn, by placing them in a damp, warm place. 
Placing seed potatoes in a tray or egg box in a bright, cool but frost-free place to encourage them to sprout prior to planting.
Refers to sprouting seed potatoes - placing them in a cool, but not cold light place so that they will sprout.Placing seed potatoes in a tray or egg box in a bright, cool but frost-free place to encourage them to sprout prior to planting.