About This Plant
Job's Tears (Coix lacryma-jobi) is a tall, warm-season C4 cereal grass of the Poaceae family, grown for its hard, bead-like grain (adlay), eaten as a whole grain and used in traditional food and medicine across Asia. It is a long-season crop, roughly 160 days from sowing to grain harvest, reaching 1.6-2.7 m with heavy tillering. Propagated mainly by seed - whose thick involucre slows germination unless warm-soaked - it also grows from stem cuttings and ratoons from stubble. Agronomically it is a moderate-nitrogen feeder whose grain yield plateaus near 80 kg N/ha, with potassium demand rising into grain fill. No hydroponic protocol exists for this field grain, so its nutrient and system-compatibility data are documented C4-cereal analogs rather than measured optima; a full grain harvest is essentially a soil/field operation rather than a soilless one.
How to Grow Job's Tears
Learn how to grow Job's Tears from seed to harvest in 160 days. Intermediate difficulty. Complete nutrient guide, pH/EC requirements, and growing conditions for hydroponics, soil & greenhouse.
Sources cited: 25.
Nutrient Requirements by Growth Stage
Job's Tears is a C4 upland cereal grass and - unlike leafy greens or fruiting vegetables - has NO published hydroponic nutrient-solution formulation; the per-stage values below are documented C4/small-grain cereal analogs (millet-primary), not species-measured optima. The reliable signals come from field and pot…
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Growing Environments
Job's Tears is fundamentally an outdoor and greenhouse field-grain crop: it is grown to a mature grain harvest almost exclusively in soil, needs a full frost-free season, and reaches 1.6-2.7 m, which makes conventional indoor grow-tent culture impractical - hence indoor is marked false while outdoor, greenhouse and…
Temperature
Job's Tears is a frost-sensitive, warm-season C4 grass - grow it warm, around 24 C optimal within an 18-30 C range for steady tillering and grain fill. The pre-enrichment optimum of 21.5 C is low for a tropical/subtropical cereal whose growth runs to 28 C and beyond. Germination is the slow step because of the hard, bony involucre: emergence is staggered and best over warm soil, with a 30 C seed-soak giving the best germination (~66%) while 40-50 C soaks depress it. The canonical germination floor of 9.6 C was unsourced and too low for this crop and has been raised into an 18-32 C warm band. Keep the whole cycle frost-free end to end.
Humidity
Hold relative humidity around 70% (roughly 60-80%); controlled adlay culture runs near 70+-5% and field ranges of 69-76% are typical of its growing regions. Job's Tears is fairly forgiving of humidity, but the main disease risks - Bipolaris leaf blight and Ustilago smut - are favoured by sustained high humidity with…
Light
Job's Tears is a full-sun C4 cereal and wants high light - target a daily light integral around 30 mol/m2/day over about a 14-hour photoperiod at roughly 600 umol/m2/s canopy PPFD (600 umol/m2/s x 14 h computes to DLI ~30, so the three values are internally consistent). The pre-enrichment DLI of 25 was too low for a…
Airflow
Provide steady horizontal air movement across the canopy, roughly 0.3-1.0 m/s. Active airflow is the practical first line against the crop's dominant fungal diseases (Bipolaris leaf blight, Ustilago smut) by keeping leaf surfaces dry and lowering canopy humidity, and it strengthens the tall culms against lodging…
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Hydroponic System Compatibility
System compatibility for Job's Tears is essentially untested: a targeted search returned NO hydroponic studies for this species, so the pre-enrichment 'DWC/NFT suitable with root support' flags were unsourced template defaults and have been corrected. Of the soilless methods, deep water culture is the only…
Growing Media
Because Job's Tears favours moist, even semi-flooded ground, a moisture-retentive but well-drained deep media bed suits it best: a coco-coir base holds water while a perlite or clay-pebble fraction preserves aeration and keeps the root zone from going stagnant. Provide ample depth for a tall, heavy-tillering grass…
Container Specs
Field agronomy, not a pot study, sets spacing: in-row 15-25 cm and rows 40-50 cm, with ~80,000-100,000 plants/ha optimal (100,000/ha at 20x50 cm for top area yield; 80,000/ha for best per-plant yield). In containers allow about 20 cm between plants…
Training & Support
Job's Tears is a robust, largely self-supporting cereal grass: in a stand its heavy tillering (10-12 culms per clump) lets plants brace each other, so field crops need no trellis or training. But culms reach 1.6-2.7 m, so tall plants can lodge under wind, heavy heads, over-fertilization or crowding, and density trials…
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Propagation
Grow Job's Tears mainly from seed, but expect slow, uneven germination: the hard, bead-like involucre limits water uptake, so pre-soaking the whole 'tear' in ~30 C water lifts germination to about 66% and speeds sprouting, while 40-50 C soaks depress it. Sow 2-3 seeds per hill about 2-4 cm deep…
Harvesting
Job's Tears is a long-season grain grass, ready roughly 4-5 months (about 160 days) from sowing, but maturity is strongly variety-dependent - documented from ~102 days in early germplasm lines to ~205 days in late accessions. Because plants grow tall (1.6-2.7 m) and set grain over an extended window, a full grain…
Planting Calendar
Job's Tears is a warm-season, long-cycle (~160-205 day) and frost-sensitive crop. In temperate Northern-Hemisphere zones, direct-sow in late spring (about May) once soil is warm and frost has passed, or nursery-start around April and transplant in May, for an October-November harvest - the season must be frost-free…
Common Issues
Job's Tears is a hardy tropical cereal grass whose most important problems are the fungal diseases and stalk-feeding insects typical of grain grasses. Two fungal diseases are its major threats: leaf blight (Bipolaris coicis, older name Helminthosporium coicis) and smut (Ustilago coicis)…
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