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QUICK FACTS Turf

 

     
 
 
Preparing the soil
Drainage
Soil pH
Levelling the site
Firming and raking
Watering
Fertiliser
Establishing the lawn
 
 
 
 
 
 
 
 
           
 
 

Laying down a new lawn

Establishing a new lawn that is lush, healthy and largely weed free is a challenge for any gardener. However, if the right steps and advice are followed, the end result of producing a new lawn that is easy to maintain and looks great is well worth the time and effort.

Preparing the soil
A thorough job of preparing the soil is critical to achieving the perfect lawn. This includes eradicating weeds, drainage, soil pH levels, levelling, firming/raking, watering and fertilising.

Eradicating weeds
Kill existing turf to eliminate unwanted lawn grasses and perennial weeds, particularly weeds that have rhizomes or deep tap roots, as they regenerate rapidly from small pieces of root. Examples are dandelion (Taraxacum officinale), nut grass (Cyperus rotundus), docks (Rumex spp.), soursob (Oxalis pes-caprae) and other Oxalis spp.

Control method
Initially, apply a broad-spectrum non-residue herbicide such as glyphosate or essential oils in an ‘organic interceptor’ to eliminate grass weeds and some broadleaf annual weeds. Plants that survive the first herbicide application should be eliminated using a selective herbicide.

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Drainage
Drainage is only required on heavy clay soils and can be improved by incorporating two parts sand to one part soil. However, a drainage system of pipes laid in a trench, backfilled with gravel is a better alternative. For most loam soils that receive 600-1000 mm rainfall, one drainpipe every 5-8 m is recommended. Heavier clay soils or sites in areas with rainfall above 1000 mm will require drainpipes laid at closer intervals.

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Soil pH
Grasses grow satisfactorily at pH levels of 5.5-7.0. In this pH range, nutrients required by turf grasses are soluble rather than being bound up in the soil. Soil pH can be tested using a kit available from garden centres. For acidic soils (pH less than 5), dig or rotavate lime (calcium carbonate) into the soil. The recommended rate depends on the starting pH and soil type (Table 1).


Table 1: Amount of lime (g/m²) required for different soils.

Starting pH Sandy Loam Clay
4.5 190 285 400
5.0 155 235 330
5.5 130 190 260

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Levelling the site
First level the site by eye. More accurate levelling can be achieved by running builder’s string on pegs inserted into the ground.

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Firming and raking
Tread the soil evenly about three times to firm it. Rake the surface to provide a fine tilth. Remove stones more than 1 cm in diameter if the soil is being prepared for sowing, or 2.5 cm in diameter for turfing. Allow 3-4 weeks for weed seeds to germinate, and treat the area with glyphosate to kill them.

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Watering
New turf requires watering at frequent intervals to keep the seed or turf moist during this initial 2-week growth period until the root systems develop. Treat the lawn as an established turf after 1 month.

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Fertiliser
A few days before establishing the lawn, apply a compound granular fertiliser containing nitrogen (N), phosphate (P) and potassium (K) to the prepared soil surface at a rate of 150-200 g/m². Rake the fertiliser into the surface.

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Establishing the lawn

Turfing
Turf can be applied any time of the year except during hot dry periods. Lay turf on to a moistened soil surface to encourage root development. Starting at the edge of the site, lay the first row of turf in a straight line. Standing on planks placed on the first row, rake over the soil on which the next row is to be laid. Lay the second row so that the turf forms an alternate bond, like bricks in a wall. Cut the edges to shape with a sharp flat or half-moon spade; use the inside of a hose for a curved edge or a plank for a straight edge. Roll the newly laid turf with a light roller (50 kg), and brush a top-dressing of sand and soil mix into the joins between the turf pieces to encourage the roots to spreads into the gaps. Water the turf thoroughly.

Sowing seed
Calculate the amount of seed required by multiplying the size of the area (m²) by the recommended sowing rate (g seed/m²). Shake the seed bag to mix the seeds.

If sowing by hand, divide the area into equal sized sections, e.g. 1 m x 1 m, to ensure an even distribution of seed cover. Measure the correct amount of seed (Table 2) for each section, and scatter half the amount in one direction and the remainder at right angles. Repeat for each section.

If sowing by machine seed spreader, divide the amount required for the lawn by half, and sow one half in one direction and the remainder at right angles to the direction of the first application.


Table 2: Seed sowing rates (g/m²)

Turfgrass species g/m²
Fescues & bents 23-30
Perennial ryegrass & other grasses 35-40
Bents (Agrostis spp.) 8-10
Carpet grass (Axonopus spp.) 8-12
Couch grass (Cynodon dactylon) 5-8
Centipede grass (Eremochloa ophiuroides) 1.5-2.5
Red fescue (Festuca rubra rubra) 15-25
Perennial ryegrass (Lolium perenne) 20-40
Kentucky bluegrass (Poa pratensis) 10-15

After sowing, lightly rake over the surface and water with a sprinkler. Sowing the grass seed at the proper depth (2-4mm) is very important because the food reserves of the seed (endosperm) may be used up before the new shoot can reach the soil surface and start making its own food through the process of photosynthesis. A biodegradable paper can be used to cover the newly sown seeds to prevent erosion on sloping lawns. The seeds will germinate 1-2 weeks after sowing.

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