This plant is highly variable. There is no one quinoa, and this rustic crop is more or less a complex of subspecies, varieties, and landraces. However, the following are its general environmental tolerances.
Daylength. Quinoa shows various photoperiod responses, from short-day requirements (for flowering) near the equator to no response in Chile.21
Rainfall. 300–1,000 mm.22 Rainfall conditions vary greatly with variety and country of origin. Southern Chilean varieties get much rain, altiplano varieties get little. As with any grain crop, quinoa grows best with well-distributed rainfall during early growth and dry conditions during maturation and harvest. It can withstand excessive amounts of rainfall during early growth and development; on the other hand, it is notable for its drought tolerance, especially during late growth and seed maturation.23
Altitude. Quinoa ranges from sea level in Chile (36°S) and coastal Peru to over 4,000 m in the Andes near the equator. It is grown mainly, however, between 2,500 and 4,000 m.
Low Temperature. Quinoa tolerates a wide range of temperatures. The plant is normally unaffected by light frost (−1°C) at any stage of development, except during flowering. Quinoa flowers are sensitive to frost (the pollen is sterilized), so mid-summer frosts (which do happen in the high Andes) can destroy the crop. Although temperatures below − 1°C damage most types, some hardy types withstand even lower temperatures.
High Temperature. The plant tolerates but does not thrive in temperatures above 35°C.
Soil Type. Quinoa can grow in a wide range of soil cidities, from pH 6 to pH 8.5. It tolerates infertility, moderate salinity, and low base-saturation levels.