It is often a dream of home owners to have a beautiful patch of bright green lawn in their backyard. Many people will be have been watching the cricket and admiring the beautiful condition of the outfield turf covering the Melbourne Cricket Ground. Some people are a little less enthusiastic about the wicket. With the Commonwealth games beginning in April at Carrara Stadium on the Gold Coast, this might be a good opportunity to talk about grass sporting surfaces and how they are maintained. In some cases you can apply these techniques in your backyard, but there are important differences. Usually the sporting grounds will have the benefit of full sun, whereas your backyard might not. Also resources like plentiful supplies of recycled water and a large maintenance budget might not apply to your backyard. There are still some techniques the home gardener can apply which will result in a great looking lawn. The Gold Coast universities like Griffith University in Southport or QUT in Brisbane, face a similar challenges it terms of pedestrian traffic wear and the need to provide an aesthetic green space for students to relax.
The first step with any garden project is the planning. Sketch your garden on a piece of paper include any large trees and shrubs. Plan out where the drainage and irrigation will be installed as this will be the first step in the construction of your garden lawn. Plan the level you want the finished lawn to be and any edging to be used. Decide the direction where you want the surface water to drain towards. New lawns will require regular watering, so if possible avoid planting in summer. Early Autumn is the best time to plant your lawn in most parts of Australia. Take note of any areas of the lawn that have only a few hours of sunlight. These areas may require a shade tolerant grass. If you have high traffic areas which will result in wear patches in the lawn, use pavers.
What are the alternatives?
If your yard is steep or very shady, consider using a non mowing solution instead. This might mean using mulch, pebbles or gravel. Another solution is to use low growing ground covers or succulents. Two native sustainable alternatives to lawn grasses are Dichondra repens and the Native Violet Viola hederacea. Some exotic herbs can also be used such as mint, thyme or chamomile. If the area is difficult to access with a mower, or if it is too steep for even the Honda self propelled mower, then the alternatives should be considered. These alternatives will save you a lot of time and money in the long term
Native Violet (Viola hederacea)
Topsoil and Lawn Aeration
Sporting grounds will normally have a thick layer of friable topsoil with a thick drainage layer underneath. The grounds are usually quite flat so sub soil drainage is very important. For your backyard or frontward lawn, the ground can be sloped a bit more to aid with drainage. Depending on the usage and also the makeup of the layers below, you could probably get away with as little as 100 to 150mm of topsoil for your garden lawn. For example green couch Cynodon dactylon, the roots will penetrate the ground up to 1.5 metres deep with much of the root mass at around 600mm deep. For this reason the layer below the top soil needs to be suitable for root growth if you want your lawn to be drought tolerant.
Levelling the topsoil
If the lawn is not reasonably flat, mowing will create bald patches on your lawn. Once a friable sandy loam topsoil has been laid, it can be levelled out using a pine retaining wall sleeper with a rope attached with screws. Aim to level the topsoil around 12 millimetres below the edging to allow for the height of the grass. The actual allowance will depend upon the variety of grass and whether it you are using a roll out grass or growing lawn from seed.
Will gypsum help?
Gypsum is the most widely used calcium additive for garden. If you really do need gypsum, you can save money by buying it in bulk from your landscape supplier. If the subsoil has a hard clay layer the moisture and the roots might not penetrate or your lawn and you could have poor drainage. Some clays will respond to the addition of gypsum. This will be the case if the clay you have is a flocculant clay. Clays like montmorillonite with high levels of exchangeable sodium will generally be improved by digging in some gypsum. You can perform a simple soil test your clay by putting it in a jar with some pure water, then stirring to create colloidal mix. The mix will appear cloudy.You then add some Epsom salts or gypsum to the mix and watch what happens. If the clay then forms flocculant, or larger, particles that sink to the bottom of the jar leaving a clear layer of water, then your clay is flocculant. Individual clay particles are made up of fine flakes smaller than 0.004 mm. Depending on the type of clay, the fine particles are held tightly together by either weak bonds in the case of kaolinite or stronger bonds if the clay contains positively charged metal ions such as sodium, calcium or potassium. The negatively charged clay particles will repel each other but the individual flakes will bond to each other.
If your garden is in one of the Gold Coast suburbs such as Carrara, Robina, Pimpana, Norwell or in some parts of Ormeau, Woongoolba or Stapylton, you might have some soil salinity to contend with. This could also be the case if you are by the sea in Biggera Waters, Runaway Bay or Hollywell. If you are close to the beach you could get sea water spray on your lawns and gardens. With saline soil, gypsum will also help as the calcium in the gypsum will remove sodium from the saline soil.
The disadvantages of gypsum
After an application of gypsum, you should follow up later with slow release fertiliser like Neutrog. Upsurge.This is because gypsum can increase leaching of iron and manganese resulting in a deficiency of these nutrients. Lawns deficient in iron will be pale in colour. If your soil is acidic, the gypsum can result in a magnesium deficiency. Use Dolomite Lime instead. It will increase the PH and add magnesium. If you are in the sandy dunes area of the Gold Coast, gypsum applied to these soils can reduce the uptake of vital zinc, copper and phosphorus. Whilst gypsum can remove sodium from saline soils and improve heavy clay soil structure , it has no direct positive effect on soil fertility. It is also important to keep in mind, most urban soils are not improved by additional gypsum. If you do have the type of soil that benefits from gypsum, apply it regularly at the rate of 200 grams per square metre for top dressing or at higher rates if you are digging it in.
Soil PH. Acid or Alkaline.
If you are on one of the parts of the Gold Coast, like the canal estates developed from mangrove and tea-tree wetlands, you may have acidic soil. This might be the case in Gold Coast suburbs like Hope Island, the Merrimac floodplain around Carrara and in the Robina Lakes system around Mermaid Waters. The disturbance of these mangrove soils during development can expose acid sulphate to the air resulting in a low PH (acidic) soil. When developing gardens in these areas, a PH test is often a good idea. If your soil is acidic, then organic matter can act as a buffer to stabilise changes in PH. Gradual applications of agricultural or garden lime will help if your soil PH is too low. I would recommend Dolomite lime for neutralising acid soils on the Gold Coast as it also adds magnesium.
It doesn’t matter whether your soil is acid or alkaline or if it is a sandy soil or a clay soil, organic matter will help. If you are digging in organic matter for a lawn, make sure it is really well spread. We have done this in the past with a rotary hoe. If your organic matter is in pockets in your soil, it will rot down over time and leave dips in your lawn. Try to keep the extra organic to less than 20% for this reason. Some sources of organic matter would be mixed animal manures, cane mulch, a manure crop or stable manure. You can even use potting mixes. Ideally the organic materials will be well composted before applying. Applying organic matter will help to reduce water usage and feed your lawn grasses. You will not see much use of organic matter on sporting fields as the priority is to create a safe even surface.
Not many home lawns get as much traffic as a golf puting green, but if you look at the putting greens at the Royal Pines in Benowa they are always looking great. If you have an existing lawn that is showing some signs of wear, consider some of the following suggestions to improve the look of your lawn. One of the lessons we can learn from the curators of sports grounds is aeration. Lawn aeration removes cores from the soil and leaves it on the surface of the lawn. Lawn aeration will ensure oxygen, fertilisers and water will get to the roots of the lawn grasses, where they are most needed. The first step is to mow the lawn as low as possible without damaging the grass. This will depend on the variety of the existing lawn grasses and how flat your lawn is. Often this will show any high spots in your existing lawn. If it is difficult to penetrate the soil with the aerator, try using a soil wetter like Seasol Super Soil Wetter and Conditioner followed by regular light watering of the soil. Use the aerator with the hollow tines and put extra holes in the high spots on your lawn.
By mowing your lawn to a lower than normal setting, followed by a thorough aeration, you will have removed a fair bit of the thatch build up. More thatch can be removed using a special detaching rake. When replanting, look for species and varieties that do not build up too much thatch in the Gold Coast climate.
Lawngrass from seed.
Following the aeration, lawn seeds can be spread over the parts of the lawn requiring repair. Look for grass seeds species suitable for south east Queensland like Green couch or Bermuda grass Cynodon dactylon or Queensland blue couch Digitaria didactyla. These varieties will take about a month to grow. Fast growing Rye grasses can be used if you are planting in the cooler months, but generally cool season grasses will not be a long term drought tolerant sustainable solution.
Top dress the lawn with a sandy loam and level it off with the back of a rake. For smaller repairs, a fine potting mix makes a good lawn top dress. The lawn can then be fertilised with chook manure like Neutrog Rooster Booster or with Neutrog Seamungus soil and plant conditioner. If necessary, top dress with some gypsum. Water with a fine mist using a soil wetter or a soil conditioner like Neutrog GOGO Juice.
Roll out Lawn
For instant effect, a roll out lawn can be used. This should be rolled out on even topsoil as soon as it is delivered. Start with laying the lawn along any straight lawn edges you might have in your garden design. Take care not to stretch the lawn rolls and push each roll firmly together without gaps. Top dress with a sandy loam or sand to fill any gaps or low spots. A lawn roller will help to even the surface and keep the lawn roots in good contact with the soil. Another advantage of the roll out lawn is that you can use drought resistant hybrid varieties that cannot be grown from seed. On the Gold Coast consider varieties like Oz-E-Tuff. For shady spots take a look at Sweet Smother Grass. If you do want a golf putting green in your backyard, the grass varieties are generally bent grass, fine fescue and winter grass cultivars and varieties for cool temperate and, dwarf couch grass cultivars and varieties for subtropical to tropical and zoysia varieties for tropical putting greens.
Your new or repaired lawn will need watering every day for a month. To save water use a soil wetter to minimise run off. Water in the evening to reduce losses due to evaporation. A liquid fertiliser high in nitrogen and iron will keep your lawn looking green. For best results, keep your lawn mower really well maintained and serviced regularly. Worn parts on your mower can result in uneven mowing. Give your new lawn about a month before mowing for the first time to avoid ripping the new grass out. Set your cutting height so that you are taking 15mm or less with each pass of the mower. Sporting grounds often use a cylindrical or reel mower, but there are a few things you can do to get a great finish with a rotary mower. For the sporting ground effect, try mowing a second time at right angles to the first direction. Some mowers have provision for a second set of blades, this will give you a finer cut. Keep the blades as sharp as possible for the best possible result.
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Alternatives to lawn
Gypsum and Clay soils