Environmental Requirements.

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.