This is the time of year when we begin to look outdoors again, and make a checklist of what needs to be done in the garden. First on my list? Tackling moss on the lawn.
Dampness is an important factor in the growth of moss. Moss is an ancient kind of plant that depends for spore germination on free surface water, and it needs water for continuing growth as it is very vulnerable to drying out. Improving drainage of the lawn reduces dampness and disfavours moss.
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' lower branches can make a big contribution to controlling moss.
Because moss is a very low-growing plant, it can survive well in exposed areas. But 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.
4. Low soil fertility
Moss has a very low nutrient requirement compared to grass and it thrives on poor soils that are low in plant nutrients while grass is weakened. Feeding a lawn with lawn fertiliser, or high-nitrogen fertiliser, promotes growth of grass and its ability to compete with moss.
5. Acid soil and lime
Moss grows better on acidic soils, and the upper layer of soil becomes acidified by rainfall. This can occur at the surface of limy soil too. Dead grass thatch on the soil surface tends to also acidify the soil. Applying some ground limestone can help to reduce acidic soil conditions and improve grass growth.
6. Moss 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.
7. Moss 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.
8. Raking 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 but removes moss, although it produces masses of moss and grass debris, which can be composted.
9. Top-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.
10. Return of moss
Moss will always return if the conditions are suitable - its spores blow in on the air. The aim should be to maintain the balance in favour of grass. Reduce dampness, shade, shelter and soil acidity, and increase nutrient levels. Luckily, moss is mostly green in colour, though it sometimes yellows and is more noticeable. Moss does not wear well under use, for instance, children's play.
What small person doesn't like getting muddy? Check out the gardening and biodiversity for kids workshop at Ballymun's Rediscovery Centre next Saturday from 2.30pm to 4pm for the secrets of herbs and veg. €10 each; eventbrite.ie (due to Covid-19, check for updates).
n Equip yourself with some interesting reading - Plant Tribe by Igor Josifovic and Judith De Graaff of Urban Jungle fame is a beauty, nuggets about house plants, care, styling, plus stunning photos. Abrams, £20, out now.
n Are you a city grower? Learn how to maximise your space, no matter how small, with a one-day course at the Organic Centre in Leitrim, March 28, €70; theorganiccentre.ie