Gerry Daly’s ten tips on how to deal with moss this spring

  • 1Dampness
  • Dampness is an important factor in the growth of moss. Moss is an ancient kind of plant that depends on spore germination and surface water. It needs water for continuing growth as it is very vulnerable to drying out. Improving drainage of the lawn reduces dampness.
  • 2Shade
  • Areas of lawn that are shaded tend to take longer to dry out and the availability of moisture promotes moss growth. However, heavy shade eventually kills moss because it needs some light for growth. Reducing shade by pruning trees can make a big contribution to controlling moss.
  • 3Shelter
  • Because moss is a very low-growing plant, it can survive well in exposed areas. Sheltered places provide ideal conditions, with slower drying of the soil surface and more moisture in the air. Reducing shelter, if that is possible, can help to reduce moss.
  • 4Low soil fertility
  • Moss has a very low nutrient requirement compared with grass and it thrives in poor soils that are low in plant nutrients and where grass is weakened. Feeding a lawn with lawn fertilizer, or high-nitrogen fertilizer, promotes growth of grass and its ability to compete with moss.
  • 5Acid soil and lime
  • Moss grows better on acidic soils and the upper layer of soil becomes acidified by rainfall. Dead grass thatch on the soil surface also tends to acidify the soil. Applying some ground limestone can help to reduce acidic soil conditions and improve grass growth.
  • 6Moss control
  • Moss can be controlled by applying sulphate of iron, also called ferrous sulphate. This pale-green fine salt can be applied directly, mixed with sand or dissolved in water. It acts by dehydrating the moss, turning it brown or black very quickly. It affects grass slightly, but it soon grows out. Almost all moss-control products are based on sulphate of iron, but there is also a product called Mo-bacter, an organic lawn feed with bacterial action.
  • 7Moss and weed control
  • Combined feed, weed and moss control products, known as 3-in-1 products, are convenient and easy to use, ideal for relatively small areas, but they work out quite expensive over large areas, where feeding, moss control and weed control can be done separately.
  • 8Raking and scarifying
  • Raking out moss helps to reduce it, but does not clear it and it is slow, hard work. Scarifying is another term for raking out moss and it can be done with a motorised scarifier or a device fitted to a lawn mower blade. This is not essential and produces masses of moss and grass debris, which can be composted.
  • 9Top-dressing and re-sowing
  • After thorough raking or scarifying, with sulphate of iron applied before or after, it can be beneficial, though not essential, to top-dress the lawn with fine top-soil. This provides new rooting material for the grass and grass seed can be sown over the area.
  • 10Return of moss
  • Moss will always return if the conditions are suitable. The aim should be to maintain the balance in favour of grass. Reduce dampness, shade, shelter and soil acidity, and increase nutrient levels.