Seasonal growth pattern
Rhodes grass grows actively following the opening rains in autumn until early June. It is generally dormant in winter, although it will continue to grow slowly in the northern agricultural region where winter temperatures are mild. It resumes active growth in early spring and grows opportunistically throughout summer depending on moisture availability.
Like most sub-tropical grasses, Rhodes grass prefers high temperatures with maximum growth at 30°C/25°C (day/night temperature) under controlled conditions. Growth is reduced greatly below 18°C/13°C and there is negligible growth when the average daily temperature is below 8°C.
| Rainfall (estimated minimum) | >425mm (>400mm south coast) |
|---|---|
| Drought tolerance | Moderate to high (depends on variety) |
| Frost tolerance | Low |
| Soil type | Range of medium- and coarse-textured soils |
| Soil fertility requirements | Favours more fertile soils in its natural habitat and is considered a ‘high fertility’ species. Very responsive to N fertiliser |
| Soil pHCa | >4.3 |
| Aluminium tolerance | Moderate |
| Waterlogging tolerance | Moderate |
| Salt tolerance | Slight (tetraploids) to moderately low (diploids). Has a number of mechanisms to deal with soil salinity including the ability to excrete sodium from salt glands on the leaves, accumulate salt in plant tissues and actively exclude salt from the roots |
| Ability to spread naturally | Very good from stolons |
| Dry matter digestibility | 61-65% (monthly cuts), 49-56% (when cut after 105-140 days) |
|---|---|
| Crude protein | 6.3% (unfertilised), 10.4-13.8% (low to high fertiliser N with monthly cuts) |
| Soil erosion control | Creeping habit provides good soil stabilisation |
|---|---|
| Weed control | Competes well with summer weeds |
Establishment
Rhodes grass is readily established from seed. The seed germinates quickly (1–7 days) depending on temperature. Rhodes grass displays good seedling vigour and often achieves full groundcover within three months of sowing. Rhodes grass has a high shoot/root ratio and a weak primary root system, so plants rely on developing a strong secondary root system and are easily pulled out by stock during the establishment period.
The suggested seeding rate is 2-5 kilograms/hectare (kg/ha) of good quality seed when sown alone or 1-3kg/ha when sown in a mixture (for coated seed use the higher seeding rates). The seed can be drilled at 5–10 millimetres (mm) followed by press wheels, or alternatively broadcast onto a firm, fine seed bed and then rolled to give good seed-soil contact. Rhodes grass seed is light and fluffy and as a result is difficult to handle, hence most seed is now sold in a coated form. For uncoated seed use a carrier to improve the flow through the seeder.
The optimum temperature for germination is 15–40°C, but a small proportion of seeds will germinate at lower temperatures. Unlike some sub-tropical grasses, Rhodes grass seeds germinate at low soil water contents and once germination has started it is irreversible. Under conditions of marginal soil moisture Rhodes grass may be the first species to germinate. Rhodes grass can compensate for poor seedling establishment by rapid stoloniferous growth to form a dense stand if it is carefully managed in the first two years.