Commonly known as Coco Grass, Java Grass, Nut Grass, or Purple Nutsedge, Cyperus rotundus belongs to the Cyperaceae family and originates from tropical and subtropical regions of the Old World. This perennial plant is widely distributed across the globe and is notorious for its invasive nature.
Nut Grass derives its name from its nut-like tubers, which play a significant role in its persistence. It is among the world’s most challenging weeds to control, often reducing crop yields and showing resistance to many herbicides. Its adaptability and aggressive growth make it a persistent issue in both agricultural and non-cultivated areas.
| Common name | Coco Grass, Java Grass, Nut Grass, Purple Nutsedge |
| Botanical name | Cyperus rotundus |
| Family | Cyperaceae |
| Species | rotundus |
| Origin | Tropical and Subtropical Old World |
| Life cycle | Perennial |
| Plant type | Herbaceous Perennial |
| Hardiness zone | 3, 4, 5, 6, 7, 8, 9, 10 |
| Sunlight | Full Sun |
| Maintenance | High |
| Soil condition | Clay |
| Soil ph | Acid |
| Drainage | Moist but Well-Drained |
| Growth rate | Fast |
| Spacing | Less than 12 in. |
| Harvest time | Fall |
| Flowering period | Spring |
| Height | 2 ft. – 4 ft. 7 in. |
| Flower color | Brown, Copper |
| Leaf color | Brown, Copper |
| Fruit color | Brown, Copper |
| Stem color | Green |
| Fruit type | Achene |
I. Appearance and Characteristics
Cyperus rotundus (coco-grass, Java grass, nut grass, purple nut sedge or purple nutsedge, red nutsedge, Khmer kravanh chruk) is a species of sedge (Cyperaceae) native to Africa, southern and central Europe (north to France and Austria), and southern Asia. The word cyperus derives from the Greek κύπερος, kyperos, and rotundus is from Latin, meaning “round”. The earliest attested form of the word cyperus is the Mycenaean Greek, ku-pa-ro, written in Linear B syllabic script.
Cyperus rotundus is a perennial plant, that may reach a height of up to 140 cm (55 in). The names “nut grass” and “nut sedge” – shared with the related species Cyperus esculentus – are derived from its tubers, that somewhat resemble nuts, although botanically they have nothing to do with nuts.
As in other Cyperaceae, the leaves sprout in ranks of three from the base of the plant, around 5–20 cm (2–8 in) long. The flower stems have a triangular cross-section. The flower is bisexual and has three stamina and a three-stigma pistil, with the inflorescence having three to eight unequal spikes. The fruit is a three-angled achene.
Young plants initially form white, fleshy rhizomes, up to 25 mm (1.0 in) in dimension, in chains. Some rhizomes grow upward in the soil, then form a bulb-like structure from which new shoots and roots grow, and from the new roots, new rhizomes grow. Other rhizomes grow horizontally or downward, and form dark reddish-brown tubers or chains of tubers.
It prefers dry conditions, but will tolerate moist soils, and often grows in wastelands and in crop fields.
The tubers are an important nutritional source of minerals and trace elements for migrating cranes.
II. How to Grow and Care
Sunlight
Nut grass thrives in full sun, where it is exposed to the sun’s rays for at least six hours per day. This level of intensity bolsters its growth and promotes a healthy life cycle. The plant exhibits a degree of adaptability and can tolerate partial sun, although its vigor and overall health may decline if deprived of its optimal light condition for prolonged periods. When grown outdoors, nut grass should be planted in areas without significant shade interference to receive adequate light. In the landscape, it flourishes when unobstructed light nourishes its robust, grass-like foliage, which is less likely to exhibit notable changes under different light exposures.
Temperature
Nut grass is thought to be native to Madagascar and grows naturally in Africa. Whether in water or soil, nut grass will tolerate light frost but not long periods of very cold weather. In cold areas, nut grass will die back with the frost but could survive the winter and show new foliage the following season; provided the roots remain unfrozen.
A temperature range of 10 to 22 ℃ is ideal, with a minimum temperature of 4 ℃ acceptable for short periods. High temperatures are not a problem, provided the water supply at the roots is kept continuous.
Watering
Originating from semi-arid regions, nut grass has adapted to survive with less frequent hydration, showcasing a moderate drought tolerance. In its natural habitat, it thrives in conditions that are intermittently wet and dry. For optimal growth, nut grass requires watering every week. This schedule allows the plant to maintain the balance it has evolved to achieve between periods of moisture and drought. As an herbaceous perennial commonly grown outdoors, nut grass’s water needs fluctuate with seasonal changes; during its active growing season, consistent moisture is key to support its vigorous development.
Soil
Nut grass will grow in any soil, from light and loamy through to heavy clay soils. Likewise, it has no preference towards pH and will grow in acidic, neutral, or alkaline soils. However, it grows best in very wet soils, and can even be grown in standing water up to 30 cm deep.
Fertilizing
Nut grass is not a heavy feeder, but small amounts of a standard-strength fertilizer can be applied once a month during active growth periods. Compared to other similar-sized plants, nut grass will not consume as much feed.
Planting Instructions
Nut grass can be planted from seed, through division or from cuttings. Seeds can either be collected from the plant or bought. These can be sown just under the soil surface, with the soil kept wet. The seedling should appear in a few weeks. When planting nut grass in pots, a high loam containing a potting medium should always be used.
In frost-free areas, nut grass can spread easily through self-seeding. If the spread is unwanted or becomes a problem, nut grass can be planted in a container and flowers picked off before they set seed.
Pruning
In the fall, dead stems should be cut back to prevent unwanted diseases. Care should be taken when pruning nut grass, as cutting leaflets will lead to the formation of unsightly brown tips. This is the plant’s natural defense, and cannot be addressed by cutting off the tips in the hope of leaving green growth behind; cutting off the brown leaflets will simply lead to new brown tips. If brown tips have formed for some reason, simply leave them to outgrow as the plant develops.
Propagation
Nut grass propagates ideally during Spring and Autumn through the method of division. Its propagation difficulty is moderate. Successful propagation is indicated by new growth and stronger root systems. Ensure proper soil drainage when dividing.
Transplanting
Transplanting nut grass is best performed during spring to early summer, a period of vigorous growth. Ideally nut grass should be relocated to a spot with well-drained soil under partial to full sun. Remember, regular watering aids in successful transplantation but avoid waterlogging. This will ensure a healthy, thriving nut grass.
Overwintering
Native to tropical regions, nut grass remarkably adapts to winter by going dormant. Its tubers serve as underground storage units, providing energy and protecting the plant from frost. Gardeners should maintain a dense mulch cover for warmth and moisture control. Remember to limit water exposure as nut grass is vulnerable to waterlogging during its dormant period. These simple winter care tips will help nut grass thrive into spring!
III. Uses and Benefits
- Ornamental uses
- Medicinal uses
In traditional Chinese medicine, C. rotundus is considered the primary qi-regulating herb.
The plant is mentioned in the ancient Indian ayurvedic medicine Charaka Samhita (circa 100 AD). Modern ayurvedic medicine uses the plant, known as musta or musta moola churna, for fevers, digestive system disorders, dysmenorrhea, and other maladies.
Ayurvedic physicians use the plant for medicinal purposes in treating fevers, digestive system disorders, dysmenorrhea and other maladies. Modern alternative medicine recommends using the plant to treat nausea, fever and inflammation; for pain reduction; for muscle relaxation and for many other disorders.
Arabs of the Levant traditionally use roasted tubers, while they are still hot, or hot ashes from burned tubers, for wounds, bruises, and carbuncles. Western and Islamic herbalists including Dioscorides, Galen, Serapion, Paulus Aegineta, Avicenna, Rhazes, and Charles Alston have described its use as a stomachic, emmenagogue, and deobstruent, and in emollient plasters.
The antibacterial properties of the tubers may have helped prevent tooth decay in people who lived in Sudan 2000 years ago. Less than 1% of that local population’s teeth had cavities, abscesses, or other signs of tooth decay, though those people were probably farmers (early farmers’ teeth typically had more tooth decay than those of hunter-gatherers because the high grain content in their diet created a hospitable environment for bacteria that flourish in the human mouth, excreting acids that eat away at the teeth).
- Culinary uses
Despite the bitter taste of the tubers, they are edible and have nutritional value. Some part of the plant was eaten by humans between Mesolithic and Neolithic periods. The plant has a high amount of carbohydrates. The plant is eaten in Rajasthan in famine-stricken areas.
- Sleeping mats
The well dried coco grass is used in mats for sleeping.
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