Killing the existing turf is necessary to eliminate unfavourable
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 (Oxalispes-caprae) and other Oxalis
Initially, apply a broad-spectrum non-residue herbicide such as
glyphosate or essential oils in ‘Organic Interceptor’
to eliminate grass weeds and some broad leaf annual weeds. Weeds
that survived the first herbicide application should then be eliminated
using a selective herbicide (see section on weed control).
Drainage is usually only required on heavy clay soils, and can
be improved by incorporating two parts sand to one part of soil.
A drainage system of pipes laid in a trench, which is backfilled
with gravel, is a more effective alternative. For most loam soils
that receive 600-1000 mm rainfall, one drain every 5-8 m is recommended.
Heavier clay soils or sites in areas with rainfall above 1000 mm
will require drains that are laid at closer intervals.
Grasses grow satisfactorily at pH levels of 5.5-7.0. In this pH
range, nutrients that the turf grasses need are soluble, rather
than being bound up in the soil. Soil pH can be tested for 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 depending on the starting pH and soil type (Table
Table 1: The amount of lime (g/m²) required for different
After levelling the site by eye, more accurate levelling can be
achieved by running builder’s string on pegs that have been
inserted into the ground.
Firming and raking
Tread the soil evenly about three times all over to firm it. Rake
the surface to provide a fine tilth. Remove stones greater than
1 cm diameter if the soil is being prepared for sowing, or 2.5 cm
diameter for turfing. Allow 3-4 weeks for weed seeds to germinate,
and treat the area with glyphosate to kill them.
New turf requires watering at frequent intervals to keep the seed
or turf moist during this initial two-week growth period until the
root systems have developed. Treat the lawn as an established turf
after one month.
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.
Turf can be applied any time of the year except during hot dry
periods. Lay turf on to moistened soil surface to encourage root
development of the turfgrass. 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 turves form an alternate
bond, like bricks in a wall. Cut the edges to shape with a sharp
flat or half-moon spade; to the inside of a hose for a curved edge,
and against 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.
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).
Fescues & bents
Perennial ryegrass & other grasses
Bents (Agrostis spp.)
Carpet grass (Axonopus spp.)
Couch grass (Cynodon dactylon)
Centipede grass (Eremochloa ophiuroides)
Red fescue (Festuca rubra rubra)
Perennial ryegrass (Lolium perenne)
Kentucky bluegrass (Poa pratensis)
After sowing, lightly rake over the surface, and water with a sprinkler.
A biodegradable paper can be used to cover the newly sown seed to
prevent erosion on sloping lawns. Germination will occur in one
to two weeks after sowing.
Lawns grown from most warm-season grasses, or the cool-season
creeping bentgrass (Agrostis palustris), which produce
stolons and rhizomes, may be established by vegetative means in
late spring and early summer. Lawns can be established by a number
Stolons or runners can be spread evenly over the prepared seed
bed, top-dress with sandy soil, roll, then water. Alternatively,
stolons or runners can be sprigged by planting them in holes or
furrows 25-50 mm deep, 80-150 mm apart, firmed in and watered. Plugs
of turf can also be planted at intervals of 25-45 cm.
Thanks to Bill Walmsley, New Zealand Sports Turf Institute, for
his article which was abridged for the section ‘Perennial
Ryegrass for Lawns and Turf’, and Sam Wakelin for the drawings
in Figure 1, Figure 2 and 3. Thanks also to Robert Lamberts for
the photographs of weeds.