Paspalum conjugatum aka Hilo Grass

Paspalum conjugatum is exceptionally easy to grow, requiring minimal care once established. This vigorous grass tolerates a wide range of conditions including acidic and nutrient-poor soils, partial shade, and even drought conditions while remaining green. Its aggressive spreading nature means it establishes quickly and fills in areas with minimal intervention. The main challenge is often controlling its spread rather than encouraging growth.

Paspalum conjugatum is a fast-growing grass with culms reaching 30-60 cm (up to 80 cm) in height. It spreads aggressively via long creeping stolons that root at each node, quickly forming dense mats. Flowering begins just 4-5 weeks after seedling emergence and continues year-round in tropical climates. The vigorous stoloniferous growth allows it to colonize large areas rapidly, often to the exclusion of other plants.

Paspalum conjugatum is native to tropical and subtropical America, with a natural range extending from Argentina and Paraguay in the south, through Central America and the Caribbean, to the southern United States. It has since been introduced and naturalized throughout tropical Africa, Asia, Oceania, and the Pacific Islands, becoming a common component of the tropical grass flora worldwide.

Paspalum conjugatum propagates easily through stolon cuttings, which is the preferred method. Take sections of prostrate culms with 2-3 nodes and plant them in moist soil. The nodes will root quickly and establish new growth. Seed propagation is possible but less reliable due to low germination rates. The plant also spreads naturally via stolon fragments and seeds that adhere to clothing, fur, and equipment.

Paspalum conjugatum thrives in tropical and subtropical temperatures and is adapted to hot, humid climates. It grows outdoors in USDA Hardiness Zones 9-11, tolerating temperatures typical of these regions. The species performs best in consistently warm conditions from sea level up to 1,700 meters elevation. It is not frost-tolerant and will not survive in temperate climates with cold winters.

Paspalum conjugatum is best adapted to humid climates and naturally favors moist environments such as riverbanks, stream margins, and irrigated areas. While it demonstrates notable drought tolerance and can remain green during dry periods, it achieves optimal growth in consistently humid conditions typical of the wet tropics.

Paspalum conjugatum is exclusively an outdoor plant, thriving in USDA Hardiness Zones 9-11. It grows from sea level to 1,700 meters elevation in tropical and subtropical regions. The grass is commonly used for pastures, lawns, and erosion control in warm climates. However, be aware that it is classified as an invasive weed in some regions including parts of Australia, and may require management to prevent unwanted spread.

Paspalum conjugatum is wind-pollinated, typical of grasses in the family Poaceae. The distinctive paired racemes produce abundant pollen that is dispersed by air currents. Flowering occurs year-round in tropical climates, beginning just 4-5 weeks after seedling emergence. The spikelets are arranged along two diverging racemes that form a characteristic T-shape.

The inflorescence of Paspalum conjugatum consists of two (occasionally three) diverging racemes, each 7-16 cm long, arranged in a distinctive T-shape that gives rise to the common name 'T-grass.' The spikelets are solitary, orbicular (round), and adorned with long white silky hairs along their edges. They are arranged in regular two-rowed patterns along a narrow, winged rachis. Flowering occurs continuously in tropical climates.

Paspalum conjugatum is susceptible to leaf rust caused by the fungus Angiopsora paspalicola, which produces yellow uredinia on leaf undersides and can reach high incidence (up to 90%) in humid tropical environments. Otherwise, the species is notably resilient and not commonly affected by serious pest or disease problems, which contributes to its aggressive growth and invasive potential.

Paspalum conjugatum contains a hemostatic glucoside called paspaloside that reduces blood clotting time by approximately 50%. Traditional medicinal uses span multiple cultures: leaf decoctions treat wounds, sores, and skin conditions; infusions address fever, flu, pneumonia, and fatigue; root decoctions are used for diarrhea and dysentery. In some regions, crushed leaf paste is applied to cuts, and preparations are made for headache relief and as antivenom.

The primary use of Paspalum conjugatum is as pasture grass for livestock, particularly water buffalo (hence 'carabao grass' and 'buffalo grass'). Under coconut plantations, yields can reach 19-30 tons of fresh matter per hectare. It serves as lawn turf, withstanding regular mowing and foot traffic, and has been used for lawns in botanical gardens. The dense mat-forming habit makes it useful for erosion control on slopes and disturbed areas.

Hilo Grass should be watered regularly, allowing the soil to dry out between waterings.

Hilo Grass loves a well-draining soil. Perlite and vermiculite help with drainage, while coco coir adds organic matter, so a good potting soil mix will have all three. You can improve store-bought soil by adding some perlite to it.

Hilo Grass requires abundant, bright and direct light. Placing it less than one foot from a window is the best way to make sure the plant receives enough light to survive and thrive. Depending on your region, however, the current weather can affect the placement of the plant in your home. For example, in some areas the sun may be too direct and intense, so it's best to place it farther away from the window. You may also need to adjust your placement according to the season as the sunlight can change intensity over the course of the year. If you live in a region with significant temperature fluctuations, such as a desert, you may need to place the plant a bit farther away from the window to avoid extreme heat or cold. With some care and attention, your Sour Grass will be sure to bring you many years of beauty and enjoyment.

Once the Hilo Grass has doubled in size or after a year has passed, it should be moved to a new pot. By replacing the soil with fresh potting soil containing all the vital nutrients, your plant will receive all the sustenance it needs, negating the requirement for fertilizer. It's important to remember that plants get their energy from the sun, not fertilizer.

Hilo Grass is not known to cause harm to humans or pets.