The Problem With Lawn Sand for Moss Control

If you're wondering whether you can use lawn sand as a source of ferrous sulphate to control your moss, I would say 'Yes - but there are considerations'.

Several have asked why I make such a big thing about using 'ferrous sulphate'. Why don't I just say 'Lawn Sand'?

Simple. Ferrous (iron) sulphate can be bought in various forms:

• as the chemical - ferrous sulphate, sulphate of iron, or iron sulphate


• combined with sand and feed as spring or autumn lawn sand - often with a weedkiller thrown in

I know it seems to be getting complicated. But it's not really.


Basically, if you can, I recommend you buy it on its own, not as lawn sand. This is not because lawn sand will not kill moss. It will - very well (don't forget to use the autumn lawn sand at this time of year; you can use spring lawn sand up till the end of August). And with the feed and the weedkiller, it is good value-for-money. But there is a problem:

GIVING SEVERAL APPLICATIONS

Because it is difficult to kill moss completely at one application (some of the dormant spores germinate later), the lawn might need more than one treatment, maybe even more.

Obviously, if the ferrous sulphate comes complete with feed (as it does in lawn sand), then this too will be added more than once. This is the problem, especially at this time of year. And of course, even if the lawn could cope, there is still the cost of the feed (and probably weedkiller) to be considered.

FANTASTIC HEALTHY TURF
I have found Vitax 'Green Up Mossfree' (based on ferrous sulphate crystals) to be especially effective, not only at killing moss, but also in conditioning the lawn. Although it looks bad for a day or two, it soon becomes fantastic healthy turf.

In previous years, I have used it in August at the first sign of moss (as already outlined elsewhere). Because there is no feed, it can be given at this time and the blackened moss raked out.

This is a great plus. Because in August the lawn is still growing strongly. So even if there is much moss, the turf will green over again before the winter. Otherwise it means staring at something resembling the dark side of the moon until next spring.

And there is still time to re-seed if necessary (this should be left one month after treating moss). If moss is treated in September or October, seed might not germinate till the following year.

So the pluses so far are:

• It can be used as early as necessary to nip moss in the bud before it becomes too established and unsightly
• Further treatments can be given right through the winter, if necessary, without further raking (since there won't be much moss)
• Re-seeded turf will rapidly green up the same year, usually within a few weeks

And there's more:

• easy to store
• can be applied by watering can (you don't need a spreader)
• can be used at any time of year, even in the summer (and you don't need one for spring and another for autumn)

CAN ALSO BE USED AS A SPOT MOSSKILLER
Once I have treated the whole lawn, I treat the odd re-emerging patches with some of the mixture in a hand spray. This kills the moss without leaving dark green feed patches.

Some have said that 'Green Up Mossfree' is not available in their local garden centre. Can ferrous sulphate be bought in any other form apart from as a component of lawn sand?

SEVERAL FORMS
Yes. It can. Ferrous (iron) sulphate is the same chemical as 'sulphate of iron' (used as a plant tonic). However, as you'll see, we need to watch the strengths, which differ for different products (wouldn't life be simpler if manufacturers made their products uniform? I suppose that would be too easy).

If you're lucky and have a horticultural supplier nearby, you can buy ferrous sulphate in 25kg (55lbs) bags. But you will need to ask about the application rate. It is not as strong as 'Green Up Mossfree' (I often feel this can be diluted anyway - 'Green Up' contains 55.5% w/w ferrous sulphate, more than twice as strong as some products).

THE NEGATIVES
There don't seem to be many:

• this way works out more expensive because you will then have to buy an autumn lawn feed. I would say it is getting rather late now for weedkiller
• Green Up contains no sand to help keep the turf open

If you can't buy 'Vitax Green Up Mossfree' ask your supplier to get it for you. You won't regret it. It really is that good.