The following is a summary of the available species of turf grass in Central Queensland and David’s findings concerning these grasses in the local context. There also follows a discussion about drought tolerance.
Green couch/hybrid couch (Cynodon dactylon)
Common varieties include Winter Green, Green Leas Park, C.T.2 and Legend.
Characteristics:
- Fine to medium leaf.
- Dark green to lime green colour.
- Mows short.
- Generally good wear tolerance.
- High fertiliser usage (300kgN/ha/year)
- Not shade tolerant.
- Handles relatively bad water.
- Noticeable seed head.
- Rhizomes which will invade garden bed.
- Very chemical resistant.
Comments and observations:
If this grass is to look good it requires a high level of maintenance. It was developed for golf courses not house yards and looks good when it is cared for by a qualified greenkeeper. Couches require regular fertilizing and constant mowing otherwise they become stalky and sparse. (Just look around and you will see plenty of lawns in that state.) When you do fertilize them they become prone to attack from grubs. Weed control is easy in hybrid couches with chemicals because the couch itself is so resilient to the chemicals. This makes couch an easy and cheap grass to grow in the farm situation but a difficult and expensive grass to maintain in house yards.
Blue couch (Digitaria didactyla)
Characteristics:
- Dark green to blue colour.
- Fine to medium leaf.
- Can be mown short.
- Reasonable wear tolerance.
- Will handle less fertiliser applications than green couch but responds well to fertiliser.
- Noticeable seed head.
- More forgiving than green couch of irregular mowing.
- Does not produce underground rhizomes.
- Not shade tolerant.
Comments and observations:
This grass was the most popular turf grass in Central Queensland but due to the fact that there is not a chemical to control grass weeds in this species it became more expensive for turf farms to produce. The hybrid couches with their chemical resistance became cheaper to buy. This does not make them a better lawn grass in house yards. Queensland Blue couch with its lower fertiliser requirement and ability to handle irregular mowing, is a better grass and is less likely to get a weed problem in a house yard.
Seashore paspalum – (Paspalum vaginatum) common varieties Sea Isle and Velvetene
Characteristics:
- Fine/medium leaf.
- High maintenance grass.
- Suitable in high salt areas.
- Short mowing.
- Medium to low nutrient requirement (200kgN/ha/year).
Comments and observations:
Not advisable to use these grasses unless you are in an extremely salt affected area or are a mad keen gardener! Seashore paspalum does not seem able to compete against any other grasses. It relies on other grasses and weeds being retarded by high salt content and unavailability of nutrients. I have seen some very nice Seashore paspalum lawns but I think it’s a case of the lawn ruling the gardener not the gardener ruling the lawn!
Kikuyu (Pennisetum clandestinum)
Characteristics:
- Vigorous coarse textured grass.
- Requires high nitrogen (300-400kgN/ha/year) (higher than green couch).
- Not shade tolerant.
- Handles wear quite well due to its vigour.
- Does not handle summer heat.
- Vigorous underground rhizomes.
Comments and observations:
Although this is quite a popular grass in southern States I would not recommend it for this area. Its has no characteristics that make it better than other warm season grasses and its strong rhizomes can make it a pest invading surrounding garden beds. I do not know any turf farm north of Brisbane growing Kikuyu.
Soft leaf Buffalo (Stenotaphrum secundatum) varieties Palmetto and Sir Walter
Characteristics:
- Coarse textured grass.
- Dense matt.
- Mow high (30-45mm).
- Medium wear tolerance.
- Medium nitrogen requirements (200kgN/ha/year).
- Handles up to 80% shade.
- Seed head not noticeable.
- More resistance to lawn grubs than couches once it is established.
- Only certain herbicides can be used to control broadleaf weeds.
Comments and observations:
This is the only decent shade tolerant grass currently available in Central Queensland. Also handles sun. Soft leaf buffalo is becoming the most popular grass Australia wide. It retains good winter colour and does not usually get affected by grubs once it is established. Generally low mowing requirements. Soft leaf buffalo will become more popular as yards get smaller and houses bigger. Broadleaf weeds can be controlled by any broadleaf weed spray that does not contain Dicamba.
Broadleaf carpet grass (Axonopus compressus)(locally sometimes called paspalum)
Characteristics:
- Broad leaf grass.
- Loves moist shaded areas.
- Mows medium height. Can be grown quite long and then mown.
- No scalding and very little cuttings.
- Not drought tolerant
- Does not handle cold conditions.
Comments and observations:
A very nice low maintenance grass in the right conditions. In older suburbs where it has been established for years it does well but I do not recommend it for new houses unless you spend large amounts of money on high quality organic soil. Even then it takes two years of constant water to begin to look any good. Its high water use makes it not a good investment in this country and it will look pretty ordinary for a couple of months over winter. Broadleaf carpet grass is suitable from Mackay north. It is the most common and prolific grass through south east Asia. It is occasionally known to cause rashes.
Tropika blue (Digitaria didactyla var. swazilandensis)
Characteristics:
- Medium leaf grass.
- Lime green to blue green colour.
- Very soft.
- Low to medium mowing 15-30mm.
- Low fertiliser requirements (100-200N/ha/year).
- Will not put up seed head until approx. 100mm high therefore no allergy problem.
- Has green leaf right to ground level so can handle irregular mowing and won’t get that dead stalky look.
- Handles up to 50% shade. (D.P.I. trials).
- As a natural grass and not a hybrid it has retained all its natural abilities to handle drought, grubs and diseases.
- Spreads from stolens (surface) not rhizomes (underground) so not invasive of garden beds.
- Vigorous growing therefore quick repairing.
- Fast grower with spring rains so may need more mowing at that stage.
- Good winter colour.
- Once established (12 months) Tropika will handle quite large lawn grub burden without affecting quality of the grass.
Comments and observations:
Tropika blue, in my opinion, is the closest thing to a genuine low maintenance grass. At Tanby Turf we call it ‘Fisherman’s Grass’ as it allows you time to pursue other activities. Tropika blue is a natural grass from Swaziland in Africa which is on approximately the same latitude as Central Queensland. It is a relative of Blue couch and has evolved under conditions of heavy grazing and irregular rain fall. In trials Tropika did not allow weed invasion even under conditions of nil nitrogen application. Under conditions of extremely low moisture Tropika will shut down but come back so quickly after rain that it will not allow weeds to penetrate. (See comment on drought tolerance at end of page). The only complaint I have had with Tropika is that it is too vigorous. However, after talking to these people it is clear they are fertilising and watering it like green couch. Once they stop this Tropika settles down.
Zoysia grass (Zoysia japonica, Zoysia matrella)
Characteristics:
- Zoysia grasses have a large range of characteristics but are generally slow growing.
- Dense stiff grass.
- Extremely hard wearing.
- Some are extremely shade tolerant and quite fine leafed.
Comments and observations:
There are not a lot of Zoysia types commercially available at the moment. Empire and Empress are probably the most common. These two are Zoysia japonicas and are not really coming up to expectations. The Zoysia matrella types look more interesting. Tanby Turf is currently trialing a Zoysia matrella type.
Drought Tolerance
From my experience all but one of the warm season grasses (Broadleaf carpet grass (Axonopus compressus) require similar amounts of water to look good. Drought tolerance is more about how the different grasses respond to extended dry times and this is where there is a variation. Most modern hybrids get sparser (thinning out) and weaker to a point that they cannot respond to rain and weeds become established in the lawn. Natural grasses, such as Tropika blue have a different way of handling extended dry times. They basically shut down completely and then when it rains come back with such vigour that they do not allow any weeds to penetrate. In trials done by the Council at Townsville, different species were planted, given water until established and then left. Six months later they were graded on percentage of cover. Tropika blue and Zoysia matrella got 9/10 whilst the hybrid couches, soft buffalo grasses, and seashore paspalums were around 3/10.