A potassium-rich diet can help lower blood pressure, and people who eat plenty of potassium have up to a 27% lower risk of heart disease (22, 23, 24, 25). ... Bottom Line: Bananas are a good dietary source of potassium and magnesium, two nutrients that are essential for heart health. Bananas do not grow from a seed but from a bulb or rhizome. The time between planting a banana plant and the harvest of the banana bunch is from 9 to 12 months. The flower appears in the sixth or seventh month. Bananas are available throughout the year - they do not have a growing 'season'.