How to Maintain a healthy green lawn
Not much beats the sight of a beautifully manicured, green lawn. It is the jewel of the garden and the perfect canvas upon which the gardener may paint the floral colours of his, or her, choice.
Once the lawn is established there are some common-sense rules that should keep it in good nick.
Since we live in a water-scarce region irrigating the lawn in the early morning, or in the evening, prevents wasteful evaporation.
The general rule is to water about 2,5cm a week in the cooler months of the season, increasing the application to about 5cm a week as it gets hotter. The easiest way to check the application rate is to place a rain gauge under the sprinklers and measure the time it takes to reach the required level.
Once a week watering encourages a deeper root system, which helps to establish the plant and keeps the lawn going through a hot, dry patch. Frequent, light irrigation keeps the roots shallow and doesn’t really let the grass gain the traction it needs.
The leaf is the production factory of the plant; healthy, functional leaf area is part of what keeps a healthy root system. Mow down too hard and the plant will lose health.
Nurserymen advise setting the mower blades high and mowing a third of the height of the grass or leaving 9cm to 10cm of leaf behind. Mowing once a week in summer is usually sufficient and sharp mower blades for a clean cut are also recommended. To keep the lawn even, change the direction every time you mow.
Gardeners who test their soil will have a better idea of soil pH and of the fertilisers they need to use. The three primary nutrients (macronutrients) for the lawn are nitrogen, phosphorus and potassium or N, P, K and their ratios are shown on every bag of fertiliser.
Nitrogen gives grass vigour and a healthy green colour, which is why yellowing lawns may indicate nitrogen shortages. However, too much nitrogen can compromise root growth by over stimulating leaf growth leading to more mowing and shallower roots. Autumn is thought to be the best time for nitrogen application. Phosphorus is important for root growth and flowering, and potassium promotes plant health and is involved in the regulation of water pressure and stress tolerance.
During the growing season some garden experts recommend fertilising with 5 : 1: 5 (at 36%) for thicker lawn growth with others advising ratios of 3 : 1 : 2.
Organic fertilisers and compost are thought to be better than synthetic fertilisers for soil health in the long term.