Ireland was overall poor, 80% of the Irish population was Catholic and landless. They rented plots of lands from mostly absentee landlords whose main interest was making profits of the land. In poor regions, like Connacht, 64 percent of all farms were only five acres or less in size. The country suffered from overcrowding, lack of capital for improvements, and too small of landholding to make significant changes. Most Irish peasants survived on a diet of buttermilk and potatoes. The potato monoculture created a high level of dependency.

The potato blight first appeared in 1845 in Belgium. Within a few months, the blight was in Ireland and infected a third of the crop. Phytophthora Infestans can run a life cycle in five days but can be dormant for years. With cold temperatures and high humidity levels, the spores can infect a crop in days and survive even rain, which carries the spores into the soil to infect the potato itself. The discoloring of the leaves and shrunken, corky, and rotten look of the potato indicated infection of the blight. The blight could survive in sprouting potatoes and infect the next crop.