Coix lacryma-jobi, commonly known as Job’s Tears or the Jesus Tears Plant, is a tall, grain-bearing grass native to Southeast Asia. It belongs to the Poaceae family and has been cultivated for centuries. Its common names derive from its most distinguishing feature: hard, glossy, tear-drop shaped structures that encase the true seed. These bead-like structures, technically hardened bracts called involucres, transition from green to a pearly gray or black when mature, providing unique ornamental appeal.
Essential Environmental Needs
Coix lacryma-jobi is a warm-season grass that grows as an annual in temperate climates but can persist as a perennial in tropical, frost-free regions. It requires a long, hot growing season, ideally with average temperatures between 9.6 and 27.8°C. The plant demands a location that receives full, direct sunlight for at least six hours per day.
A consistently high level of moisture in the soil is the most important environmental factor for successful cultivation. Job’s Tears naturally occurs in flooded areas, ditches, and near stream banks, making it a wetland indicator species. The soil should be rich and loamy, with excellent moisture retention, though it can tolerate heavy clay. An ideal soil acidity is slightly acidic to neutral, but the plant is adaptable and performs well in a pH range from 4.5 up to 8.4.
Planting and Propagation Methods
Starting Job’s Tears from seed requires preparation to overcome the tough seed coat. Gardeners should nick the hard seed casing with a knife or file, followed by an overnight soak in water, which significantly improves germination rates.
For regions with shorter summers, starting seeds indoors four to six weeks before the last expected frost is recommended. Plant the seeds about a half-inch deep in a seed-starting mix and keep them consistently moist at approximately 70°F. Once the danger of frost has passed, established seedlings can be transplanted outdoors, spaced about 10 to 12 inches apart. Direct sowing outdoors is also possible once the soil is warm, typically after the last frost, but this may result in a shorter growing period for seed production.
Ongoing Maintenance and Pest Management
The maintenance schedule for Job’s Tears revolves heavily around its need for abundant water, especially during the vegetative growth phase. The soil should never be allowed to dry out completely, simulating the moist or boggy conditions of its native habitat. Reduce irrigation only as the grain heads begin to form and mature, which maximizes the final seed yield.
As a tall, fast-growing grass that can reach heights of four to six feet, the plant benefits from rich soil and regular feeding. Applying a balanced fertilizer, such as a 10-10-10 formulation, or regularly incorporating organic matter like aged manure throughout the growing season, supports its vigorous development. Pruning is often limited to removing dead or damaged foliage to encourage bushier growth. Very tall plants in windy locations may benefit from staking to prevent lodging.
Pest issues are generally minimal, but soft-bodied insects and mollusks can occasionally pose a threat. Slugs and snails are drawn to the plant’s lush, moist environment and can be managed using physical barriers or commercial organic slug pellets. For other soft-bodied pests like aphids, an application of food-grade diatomaceous earth around the base and on the leaves provides effective control. This powder must be reapplied after any rainfall or heavy watering, as moisture deactivates its effectiveness.
Harvesting the “Tears” and Common Uses
The unique seeds of Job’s Tears typically mature within four to five months of planting. Harvesting should begin when the involucres have fully hardened and changed color from green to a dark gray, brown, or black. For a large harvest, the entire stalk can be cut at the base and allowed to dry for several days before the seeds are threshed out.
The hard-shelled variety, C. lacryma-jobi var. lacryma-jobi, is primarily harvested for ornamental purposes. These hard, naturally perforated beads are widely used for making jewelry, rosaries, and craft items due to their durability.
The cultivated soft-shelled variety, C. lacryma-jobi var. ma-yuen, is harvested as an ancient cereal grain and food source. These edible seeds require hulling or husking before consumption. Afterward, they can be cooked like rice, ground into a nutritious flour, or used in soups and teas. Beyond culinary use, the seeds are also valued in traditional medicine for reducing inflammation and acting as a diuretic.