Winter peas (Austrian winter peas or field peas) are a cool-season annual legume cultivated primarily for agricultural benefits. This subspecies of the common pea (Pisum sativum) has been bred for increased cold tolerance, making it suitable for planting in the fall or late summer. Although the peas are edible, this variety is not grown for fresh consumption like garden peas. Instead, it functions mainly as a cover crop—a non-cash crop planted to manage soil health and fertility between primary production cycles. Winter peas grow during cooler months, protecting the soil and adding valuable nutrients for the subsequent cash crop.
Defining Characteristics
Winter peas (Pisum sativum subsp. arvense) exhibit a vining growth habit, producing thin, hollow stems that can reach up to four feet in length. The plant develops small, pale green leaves and uses slender tendrils to climb and spread. This prolific growth creates a dense mat of biomass above the ground, which is important for soil cover.
The characteristic that distinguishes winter peas from standard garden peas is their cold hardiness, allowing them to survive mild to moderate winter conditions. While tolerance varies by cultivar, they can withstand temperatures dipping into the range of 0 to -10 degrees Fahrenheit, especially with snow cover. As a winter annual legume, it is planted in the fall, becomes semi-dormant during the coldest period, and resumes vigorous growth in the early spring. Flowers are generally pinkish-purple or white, appearing in the spring before maturity.
Role as a Cover Crop
Winter peas are valued for their ability to enhance soil fertility and structure. As a legume, the plant forms a symbiotic relationship with specific soil bacteria, Rhizobium, which colonize its roots. These bacteria convert atmospheric nitrogen gas into a plant-available form through nitrogen fixation, storing it in small root nodules.
This natural fertilization process contributes 90 to 150 pounds of nitrogen per acre to the soil, reducing the need for synthetic fertilizers for the following crop. The dense surface growth provides excellent erosion control by shielding the soil from heavy rain and wind. The extensive root system also helps break up soil compaction and improves water infiltration, increasing the soil’s capacity to hold moisture. Furthermore, the rapid growth of the pea biomass suppresses winter weeds, reducing the need for herbicide application.
Planting and Termination
Winter peas are managed to maximize benefits for the subsequent cash crop, with planting occurring in the late summer or early fall, six to eight weeks before the first hard frost. Seeds are planted one to two inches deep into a firm, moist seedbed; drilling improves seed-to-soil contact and establishment. Seeding rates for a monoculture range from 50 to 70 pounds per acre when drilled. It is important to inoculate the seeds with the correct Rhizobium strain to ensure optimal nitrogen fixation.
Termination, the process of killing the cover crop, is timed to coincide with the plant’s peak nitrogen content, typically at the full-bloom stage in the spring. Growers commonly terminate the peas using mechanical methods (mowing, rolling, or light tilling) or herbicides. Proper timing halts the pea’s growth and allows the accumulated biomass to decompose, releasing fixed nitrogen and nutrients into the soil. Delaying termination too long can result in the cover crop using up too much soil moisture needed for the following spring-planted cash crop.