Job for the weekend…
With Horticulturist Gareth Austin
This weekend it’s forecast to turn cold after a fantastic week of weather, the sunshine has really warmed up the soil and the growth is coming thick and fast in the garden. Where there was no colour there is now daffodils and other spring flowers appearing overnight. Our Donegal Daily job for the week is ‘Treating moss in the lawn’.
Lawn moss can be caused by a combination of factors – Soil Compaction and Acidic soil being the two main causal agents for moss on lawns. Over a period of years cutting grass – simply the act of walking up and down the same strips compacts down the soil layer in the root zone, thus preventing water flow through the soil, and air from circulating around the root zone of the grass.
The water is then retained near the surface of the soil, creating great breeding ground for moss (aswell as slowing down the growth of the grass, weakening its strength and this in turn allows entry for weeds), as there’s less air in the rootzone the ground doesn’t dry up as quickly and the grass roots grow slowly, giving poorer performing grass, rendering the grass less able to compete with the moss and weeds.
Rainfall is naturally acidic, and over a period of time will acidify soil, this couple with grass being cut and removed depleted the availability of calcium in the soil, when the soil pH gets lower, the growth of the grass slows down as the nutrients become less available, this in turn reduces the grass ability to compete with weeds and moss favours an acidic soil to colonise.
So to combat the moss it’s a two pronged approach, firstly we kill the moss, secondly we try to create conditions the moss doesn’t flourish in.
To kill the moss: Cut the grass, then treat the lawn with Sulphate of Iron (available from Aurivo Co-Op or Garden Centres), after the moss goes black its then time to rake this out as best you can, or better still hire a Scarifier from Letterkenny Tool Hire and give it a run over with this. This will rip up the dead moss and the thatch layer (which is accumulated dead grass), you can then run over with the lawnmower to gather this up.
Then spike the lawn at regular intervals with a garden fork, or in a back lawn get back on the phone to Letterkenny Tool Hire and get a Lawn Aerator on hire, the garden fork creates small holes in the soil which you’re then gonna fill with Sharp Sand (again Aurivo Co-op or Builders Yard).
This addition of sand helps to aerate the ground, and allows the air to penetrate deep into the root zone of the grass. Next step is to apply some Lime over the lawn (handy tip is to give the soil a wee pH test before you do this, this way you’ll know how much lime you need to get a target pH of 6.5). and last but not least is an oversow of fresh grass seed, which you’ll need if you’ve removed a load of moss.
If you leave bare ground then weeds will colonise this, so oversow any bare patches with a mix of No.2 lawn seed mixed with some screened soil or compost.
The whole aerated and sanding the lawn might be something you do every 5-10 years, the liming every 3-4 years but its worth applying some Sulphate of Iron to the lawn every Autumn/Spring, even if you’ve just a bit of moss it’ll knock it on the head, stop it from competing with your grass. Also the Iron will give your lawn a healthy dark green colour, and will control many of the weeds, such as daisies.
Next Week….It’s your Duty to be Fruity!
Gareth Austin is resident Horticulturist with BBC Radio Foyle, a member of the Chartered Institute of Horticulturists and lectures in Horticulture with Donegal ETB. For more see www.garethaustin.com or join Gareth on Twitter @GardenerGareth