Adapts to most soils, but grows best in fertile, well-drained loam.
Quinoa seedlings have a low tolerance for cold, so wait to plant until after the last spring frost has passed. Mature plants are easier to harvest after a light frost in the fall.
Before planting, amend the soil with a light application of a balanced organic fertilizer.
Single Plants: 1′ 11″ (60cm) each way (minimum)
Rows: 1′ 5″ (45cm) with 2′ 11″ (90cm) row gap (minimum)
Sow and Plant
Plant in spring, just after the last frost, by sowing seeds barely covered with soil in uniform rows. Keep soil moist until the seedlings sprout. Weed by hand until the plants are 4 inches (10 cm) tall, gradually thinning plants to 18 inches (46 cm) apart. As the plants grow, they will shade out most summer weeds.
Quinoa is closely related to the weed known as lambs’-quarters, so it can be difficult to tell the two plants apart. Quinoa grows to 4 feet tall (1.2 m) in dry climates, but can grow twice as tall with abundant rainfall. Tall varieties may need staking to hold them upright when they become top-heavy with maturing seed clusters.
Wait until the plants shed their leaves to harvest your quinoa. When the weather is dry, bend over seed heads into a large bucket and clip them off. Working in a dry place, strip off the seeds, use a fan to winnow out debris, and spread the seeds on screens or trays to finish drying indoors.
Flea beetles may leave tiny holes in leaves, but the plants usually outgrow the damage. Several types of caterpillars may feed on quinoa, but they are easily controlled with an organic pesticide that uses Bacillus thuringiensis as its active ingredient.