Under certain circumstances
when a lawn becomes patchy, a mixture of desirable and undesirable grasses
and is overrun with broad leafed weeds the only option left open to the
home owner is to take the drastic measure of a total renovation of the lawn.
Investigate and identify the factors
that have contributed towards the problem
One of the most important factors to consider before one embarks on
such a drastic and costly measure is why the lawn is in the conditions that
it is in the first instance. If the factors resulting in the poor condition
of the lawn are not clearly identified and rectified then the whole costly
exercise will most probably be a total waste of effort and money.
On analysis of the factors that have led to the lawn being in the condition
that it is in, one will find a combination of physical and cultural factors
which combined caused the problem.
The two most frequent factors are the improper
preparation of the area to be planted to lawn and improper management
of the lawn.
As regards improper preparation the most common factors that I have
observed to be significant in particular on the heavy low fertility clay
soils found in many parts of Auckland are.
- The failure to provide adequate drainage.
- The failure to incorporate organic material
into the soil.
- The failure to add gypsum and super phosphate
to the soils.
- The failure to prepare the seed bed by
tilling the soil on which the seed is to be sown.
The most frequent factors encountered as
regards the improper management of lawns are.
- Cutting the lawn too short or scalping
in many cases right down to the growing point or below.
- The periods between grass cutting are
too long, no more that one third of the leaf blade should be removed at
any one time.
- The failure to fertilise in particular
lawns that are under heavy stress due to being cut too short.
- Providing no or insufficient water during
hot dry spells.
If these factors are not addressed it is pointless to renovate your
lawn.
The process of renovation
The entire area must be sprayed with glyphosate (Roundup) to ensure
that all existing grass and weeds are killed off. Some time needs to be
allowed to ensure that all the grass and weeds are dead, any areas missed
must be re-sprayed.
Any ground modelling, drainage work or the installation of irrigation
that is required must be done now.
Thereafter the whole area is to be covered with a layer of suitable
organic matter, such as lawn mix from Living Earth to a depth of between
50 mm and 75 mm, an application of super phosphate at the rate of
50-100 grams per square metre and gypsum at the rate of 500- 1000 grams
per square metre is also required. The seedbed is then prepared by tilling
the entire area with a rotary hoe followed by a light rolling with a roller.
The seed bed is then given a final levelling to give a good even surface.
Seeding of the lawn area can be done by means of a rotating disc or
drop spreader, or by means of hydromulching. Spreading seed by hand will
not give satisfactory results. When seed is spread other than by means of
hydromulching the seed would need to be lightly worked into the soil surface
with a rake and would need irrigating.
A lawn can be established at any time of the year although the best results
are obtained in spring and autumn.The optimum time to establish cool-season
turf grasses in the Auckland City area is during the autumn this is
when nature establishes cool-season grasses; therefore, the best results
with the least amount of work occur at this time. Do not delay
seeding or the grass may not establish sufficiently before winter allowing
winter growing weeds to become a problem.
Choosing the grass variety to be planted.
In the Auckland area the most frequently planted grass planted
in full sun situations is perennial Rye grass. Perennial Rye grass (Lolium
perene) is winter growing, a winter-hardy turf grass capable of withstanding
temperature and moisture extremes. During hot, dry periods it tends to
become dormant and lose colour. If high quality is desired during the
summer period, lawn irrigation is often necessary. Perennial Rye grass
performs best in full sun, for shady areas a mixture of perennial Rye
and chewings Fescue (Festuca nigrescens) usually give the best results.
Bent or common bent (Agrostis capillaris) also known as browntop is to be
found in many cool-season grass mixes planted in this region.
Fertilizing, Watering and Mowing
Apply a high nitrogen fertilizer over the lawn and water it
in completely, this will not be necessary with hydromulching as the fertiliser
is added to the mulch mix. To ensure proper germination you will
need to keep the seed moist. This means watering three to four times
daily. Light, frequent watering will yield the best results.
Perennial Rye will germinate
in approximately 1-3 weeks. Four to five weeks after germination,
apply a quick release nitrogen fertilizer at a rate of 30-40g/square metre.
Repeat this procedure at four to six weeks intervals until the lawn is
fully established, thereafter follow the recognised fertilizing practice
for established lawns.
Mow your new cool-season grass as soon as it is 50-70mm tall
with the mower set at 50mm. Continue to mow at that height until the
lawn is well established, thereafter the cutting height can be lowered
gradually to between 25 and 40 mm.
The root system of your new turf will continue to grow and strengthen
even if the grass blades have virtually stopped growing for the season.
In the spring you will be rewarded with a quick thickening, healthy
lawn.
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