Favorable climatic conditions and suitable soils support the cultivation of grain pea for livestock feed in south-east Europe. Grain pea (Pisum sativum ssp. sativum L.) is very plastic. This means it adjusts to conditions while growing. It is able to enrich the soil with nitrogen, which makes the crop attractive to farmers. Pea provides a valuable plant protein that can reduce the use of imported protein in livestock feeding. The crop is cultivated for dual purposes in Bulgaria: firstly as forage, which is harvested green, and secondly for grain. The crop is rotated to exploit its fertility-raising features. Spring-sown pea in Bulgaria has a short period of rapid vegetative growth in the months of April and May. This is followed by grain development in May and June. Favorable growing conditions and the availability of water from the soil are key to the yield potential generated in spring and early summer.