Moss Control

By The Groundsman - Issue 14 (1995)

You won’t need me to tell you that we have had the wettest winter since records began, and those of you who know anything of the ways of nature will be looking apprehensively at the lawns to see what havoc has been wrought in the close season. With the mild November and December, leaves were still on the trees on Boxing Day, and I can only hope that those of you who enjoy winter play used the besom to good effect! So let’s hope that you have no soggy rotting leaves to contend with, in addition to the moss, which I’ll wager is there in profusion.

It’s almost inevitable that you’ll have cushion moss, the tiny upright stems packed closely together, which thrive on closely mown lawns. The golden feathery stems of the trailing mosses will be around the root system of any trees adjacent to courts. And then there is the possibility of the upright mosses. All will have thrived on the continually damp conditions of this winter, as waterlogged patches, probably around the hoops, almost always develop moss.

But too much moisture is not the only high risk factor, as moss thrives equally well on infertile but well drained soil. Skimping with the summer and autumn feeds last season, as well as over acidity, combined with compaction will all have added to the reasons for an abundance of this unwelcome plant amongst your fine fescues. So what are we to do about it?

There are two recognised courses of action. Lawn sand will burn out moss and at the same time provide a boost to grass growth. It must be applied strictly in accordance with your supplier’s instructions, as the active ingredient, ferrous sulphate, can scorch the grass if carelessly used. It only kills the top growth, leaving the root system intact. But lawn sand will keep in check a wide variety of your lawn weeds as well as the moss. Additionally its other ingredient, ammonium sulphate, will give the lawn a good healthy vibrant look, as any brown patches will he greened up.

Use on a sunny morning, when the grass is still moist from dew, and when there is prospect of fine weather for 36 to 48 hours. You mustn’t mow or walk on the lawn until it rains, as, perish the thought, you will need to get out the hose, as the product does need watering in. Once the moss dies off, it’s time for the scarifier to gouge out any thatch and the dead debris.

Easier to use, but considerably more expensive, is to water on a dichlorophen product. As with the lawn sand, the lawn will need scarifying in two weeks after application. But is there anything we can do to prevent moss in the first place - for remember, moss is a symptom of neglected or misused turf! Well, firstly, improve the drainage. This means hollow tyning in September, before top dressing followed by overseeding. Secondly, remember that your fine grasses have equal needs to any other living organism - consequently, a correctly balanced diet of nitrogen, phosphates and potash is vital, spring, summer and autumn. Next, reduce shade, by pruning branches from trees, but better still, remember, trees in the immediate proximity of your lawn spell out what the law refers to as "an indifferent lawn". And finally, cut the grass at the correct height.... and if I follow this last requirement, you will only grumble that the lawn hasn't been cut!! The truth of the matter is that this near shaving of lawns only weakens fine grasses, which then have difficulty in competing with the moss plants in the early spring. So, if you cannot close a lawn in September, and carry out the above work, and insist on closely cropped grass, then face the inescapable task of attempting to eradicate moss each April. Ah well, it keeps me in a job!