Quinoa

Sow in early spring, as soon as the seedbed can be worked

Direct sow about a half-inch deep at 1 to 2 teaspoons (5-8 g) of seed per 100 square feet, in rows 8 to 24 inches apart. Expect near 100 percent germination at soil temperatures from 36F to 68F, with seedlings up in three to five days. Sow thick and thin later, and double the rate in less than ideal conditions. Quinoa aborts flowers and goes pollen-sterile above 95F, so sowing early is what puts flowering and grain fill ahead of peak summer heat. Quinoa also grows slowly right after germination, and a late sowing hands the bed to weeds during exactly that window.

⚠ Do not place seed in direct contact with fertilizer. WSU observed inhibited germination when fertilizer was applied at seeding, the strength and proximity burning the very small seeds.

Water through flowering and grain fill, and never overhead

Flowering and grain filling, roughly 40 to 80 days after sowing, are the stages that decide the crop. If your summers are hot and dry, drip about 0.6 inches of water once a week through this window, delivered at the root zone. In WSU trials, drip irrigation at this stage raised yields nearly fivefold over unirrigated quinoa, and in a hot year the irrigated plots produced seed when the unirrigated plots produced none. Overhead irrigation wets the canopy, and downy mildew spreads on cool wet leaves at 90 percent humidity or greater.

⚠ Do not irrigate fully at every stage. That encourages tall plants that lodge and delays senescence, which makes harvest harder and drags the crop into autumn rain.

Work in modest nitrogen at bed prep, after a soil test

Following a soil test, incorporate roughly 0.25 to 0.4 lb of nitrogen per 100 square feet into the seedbed, as aged compost, composted manure, or blood meal. For containers, 2 teaspoons of blood meal in a 12-inch pot hits the low rate and 1 tablespoon plus 1 teaspoon hits the high rate. Reported quinoa yields have almost tripled at 0.25 lb N per 100 square feet compared to no fertilizer, but the curve flattens fast. Quinoa is a luxury consumer of nitrogen: extra N buys leaf and stem rather than grain, and brings late maturity and lodging with it.

⚠ High nitrogen favors aphid reproduction, so prefer a less soluble organic source. Container plants lack the soil buffer against fertilizer toxicity, which shows as poor germination, stunting, and low yield.

Thin to 3-5 inches about two weeks after emergence

Two weeks after emergence, thin the stand to 3 to 5 inches between plants. Thinning wider, up to 12 inches, gives larger branching plants carrying several seed-bearing panicles. Choose the wider end in humid regions, the closer end where the season is short. Sowing thick and thinning later is what guarantees an even stand, since 100 percent germination and emergence is unlikely. Spacing then does real work: wider inter- and intra-row spacing increases airflow, which is the main cultural control for downy mildew and speeds dry-down; close planting reduces branching and brings maturity earlier.

⚠ Thin carefully by eye. Young lambsquarters is nearly indistinguishable from quinoa seedlings, so pull anything that is not in the planting row rather than trusting leaf shape.

Scout panicles at flowering for lygus bugs and stem borers

Inspect panicles closely as they develop, and again at the seed milk stage when the seeds are formed but still soft and milky inside. Look for lygus bugs, which are pencil-eraser sized, pale green to yellowish brown, with a large light triangle on the back, and for pin holes along stalks left by boring larvae. On a small plot, vacuuming individual panicles with a cordless hand vacuum is effective. Do not confuse lygus with the beneficial bigeyed bug. Lygus pierce flowers and developing seed and destroy terminal meristems, causing seed abortion and bushy plants. WSU found lygus populations peak in the three-week period following bloom and preceding seed set. Boring larvae gut the stem and can take the whole crop when they hit early growth.

⚠ WSU reports no home-garden pesticide carries a label allowing use on quinoa for these pests. Tolerances for chlorantraniliprole, spinosad, and spinetoram have been established and registered only in some states, so confirm your own state registration before considering any spray, and never spray a panicle that is in flower.

Aphids: neem oil on the leaf undersides, before flowering

If aphids build up on foliage, spray neem oil onto both the tops and the undersides of leaves, since that is where they feed. First remove nearby sow thistle and mustard weeds that build aphid populations, and check any purchased transplants for aphids before planting them. Aphids suck sap until leaves curl, distort, and go necrotic, and their honeydew coats stems and blocks light while inviting fungal growth. They also vector plant viruses, to which quinoa is notoriously susceptible.

⚠ Few home-garden pesticide products are allowed on grains. Use only a neem product whose label lists grain crops, and follow that label. Do not apply while panicles are in flower, and limit the number of sprays, as they disrupt the lady beetles, green lacewing larvae, syrphid fly larvae, and parasitoid wasps that hold aphids down for free.

Harvest at hard dough, and beat the first autumn rain

Watch for the stalks and leaves to lose their green and turn autumnal orange, yellow, red and pink, and for the leaves to drop. Shake a few seeds into your hand: quinoa is ready when the seed is barely dented by a fingernail and threshes free of the panicle easily. Branched plants ripen unevenly, so take the leading panicle that dries down first and the rest days or weeks later. Mature quinoa seed germinates within 24 hours of exposure to moisture. Rain on a standing ripe crop sprouts the seed right on the panicle, and complete crop loss is possible. Prolonged rain or wind also lodges plants once the heads are full of seed.

⚠ If rain is coming, cut the plants and let them dry down in a sheltered location rather than waiting on a perfect field dry-down.

Thresh, winnow, then wash the saponins off the grain

Thresh by rubbing panicles between your hands or striking them against a hard surface over a clean tarp. Winnow with a fan, letting seed fall onto cloth while the air carries the lighter chaff away. Then remove saponins by repeatedly soaking the seed, agitating it, and dumping the water until soapy bubbles stop forming, or by rinsing under fast hot running water until it runs clear. Most quinoa varieties coat their seed in saponin, a bitter soap-like compound that foams in water and makes the grain unpalatable straight off the plant. Saponin-free sweet varieties exist but are hard to buy as commercial seed.

⚠ Dry seed to about 13 percent moisture before storing, or it loses viability and molds. Spread it in full sun for several days but bring it in each evening in climates with evening dew or rain. Taste a few seeds to confirm the bitterness is gone before cooking a batch.