Common Name: Johnson Grass

General Information

Sorghum halepense is an erect, perennial grass, with culms from 60-290 cm in height. It forms an extensive underground root systems[].
The plant has an edible seed that is occasionally eaten. It also has medicinal uses and has potential as a source of biomass.
Johnson grass is thought to have originated in the Mediterranean region, but is now widely distributed as a serious weed in warm-temperate regions of the world[]. It is one of the 10 most noxious weeds in the world an is a serious weed problem in cotton, corn, soybeans, sugarcane, fruit and nut orchards, and vegetables, and mentioned as a problem in 53 countries[].This species It is a very aggressive plant[], spreading freely at the roots and only suitable for large areas[]

Known Hazards

The pollen can induce hay fever[].

Botanical References

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Range

Northern Africa, through western Asia and Arabia to central Asia, India, Myanmar, Thailand, Laos and Vietnam.

Habitat

Dry open habitats[]. Moist areas on river banks, in clay soils and wet sandy soils[].

Properties

Weed Potential	Yes
Edibility Rating
Medicinal Rating
Habit	Perennial
Height	2.00 m
Growth Rate	Fast
Pollinators	Wind
Cultivation Status	Cultivated, Wild

Cultivation Details

Originally from the Mediterranean and west Asia, Johnson grass has spread to many areas of the world, including the tropics. It is best adapted to warm humid summer-rainfall areas in the subtropics, not growing well in strictly tropical areas[]. It grows best in areas where annual daytime temperatures are within the range 24 - 32°c, but can tolerate 15 - 36°c[]. Temperatures below 13°c tend to inhibit flowering[]. When dormant, the plant can survive temperatures down to about -7°c, but young growth can be severely damaged at -1°c[]. It prefers a mean annual rainfall in the range 500 - 750mm, but tolerates 450 - 1,500mm[].
Prefers a warm sunny position[]. An easily grown plant, it succeeds in ordinary garden soil[]. It is adapted to a wide range of soil types, including upland clay, but seems to do best on porous fertile lowlands and river bottoms[]. It does well on heavy clay soils of relatively high fertility and water holding capacity[]. Prefers a pH in the range 6 - 6.8, tolerating 4.9 - 8.2[].
A parent of the cultivated Sorghum (S. Bicolor)[].
Classified as a short day plant, it does not flower if the daylight hours exceed about 13 hours per day[].
Rhizomes production may be 10-50 t/ha. Seed yields of 0.3 t/ha are considered good[].
A day-length of 12 hours is thought to be the optimum for flowering, with above 14 hours of light the grass fails to flower, and above 16 hours all growth processes are inhibited[].

Edible Uses

Seed - raw or cooked. It can be used whole in a similar manner to rice or millet, or it can be ground into a flour and used as a cereal in making bread, cakes etc[, ].

Medicinal

The seed is demulcent and diuretic[].

Other Uses

The plant is a potential source of biomass with yields of up to 19 tonnes per hectare[].

Propagation

Seed - sow mid spring in a greenhouse and only just cover the seed. Germination should take place within 2 weeks. Prick out the seedlings into individual pots once they are large enough to handle and plant them out after the last expected frosts.
Division in mid spring as the plant comes into new growth. Larger divisions can be planted out direct into their permanent positions. We have found it best to pot up the smaller divisions and grow them on in a lightly shaded position in a cold frame, planting them out once they are well established in the summer.