People often associate the sight of deep-green grass with a healthy lawn. While light green grass may be the first sign of a nutritional deficiency, light shades of green may be the result of insufficient amounts of sunlight. Understanding the cause of your light green grass can help you determine the best way to restore your lawn's lush form.
Grass is the most common ground cover in parks and yards. Some varieties of grass, such as Kentucky bluegrass, make suitable surfaces for gardens with pet and people traffic, while other grasses, like Timothy grass, are useful as livestock forage and erosion control along roadsides. While different varieties of grass naturally vary in colour, grass that appears lighter than its normal colour can signal the presence of a lawn problem. Unhealthy grass may appear paler than usual, fade from dark green to light green or take on a yellow hue.
The most common cause of a light green lawn is a lack of nitrogen. Nitrogen is an important nutrient for grass growth. A lack of nitrogen can result in slow growth and light colours. Over time, lawn grasses can deplete the soil of available nitrogen. Nearby trees and shrubs may also rob nitrogen from the topsoil surrounding the grasses' roots. Annual applications of lawn fertiliser can replace missing nitrogen and help grass quickly return to its normal shade of green. Applying nitrogen fertiliser in the spring will help green up the lawn and encourage rapid growth.
Most lawn grasses require a majority of daytime sunlight. Grass that grows in shaded areas beneath trees or on the north side of structures can lose its deep green colour. This can result in different shades throughout the lawn, with the pale grass limited to areas with inadequate light. Removing the lower branches from overhanging trees, as well as thinning out the canopy, can help restore sunlight to the underlying grass and deepen its colour.
Diseases that change grass colour are usually limited to specific spots within the lawn, rather than widespread areas. A disease known as yellow patch causes spots of light green grass that measure about 5 to 7.5 cm (2 to 3 inches) across. As the disease progresses, the light green colour turns to yellow and brown. Sclerotinia dollar spot is another disease that causes light patches of grass that fade from green to pale yellow. Some types of rust disease can also cause light-coloured patches. Treating these conditions with a fungicide can help restore health and colour to your lawn.