Place the sunflower seeds in the container. Sow 2 to 10 seeds in pairs, depending on the size or length of the container you've chosen. Not all of the seedlings will be kept, so don't worry too much about squashing them in at this stage but do be prepared to discard all the weaker appearing seedlings later. When planting, plant 2.5cm (1 inch) deep and at least 10cm (4") apart.