Beware Of Moss In Lawn

The increasingly heavy overnight autumn dews in the UK create ideal conditions for moss establishment (or re-establishment!). Spores which have lain dormant during the summer months become active and can soon overpower even the healthiest of lawns. So we need to beware. Now is an ideal time to get down close to the turf and examine it carefully for strands of moss.

If moss has previously been a problem, I recommend an application of ferrous sulphate (19% soluble sulphate of iron) at 1 ounce per gallon of water per 10 square yards (35g per 4.5 litres water per 9 square metres). With the right rose, it doesn't take long to apply with a watering can (you might need to experiment with different ones to get the delivery rate right). I would give this treatment whether you can see any moss or not; any present will turn black almost instantly. You might be amazed at how much there is.

REPEAT TREATMENT IF NECESSARY
I dealt with moss treatment in great detail last year (see last autumn's lawn posts). But I didn't make it clear that we need to keep an eye out for moss re-establishing after a month or two. If it does, then repeat the treatment. You can do this as many times as necessary.

If you keep 'nipping it in the bud', you will keep it in check without disfiguring the lawn. i.e. the dead moss will quickly grow over, so there should be no need to rake.

RAKE OUT IF NECESSARY
If moss is really bad, then now is the time to kill it off and rake it out. There is still time for the turf to at least partly recover before winter. This way it will not look as unsightly as it would if left till later, or - even worse - next year.

Dealing With Moss In A Summer Lawn

Apply Summer Feed First (should control it); Mosskill Later, If Necessary


Treating a lawn for moss is rather like a doctor treating a sick patient. The first thing to do is control the suffering - usually with drugs or other chemicals - then work on changing, if possible, the conditions which caused it. And just like any sickness or ailment, treatment can be applied AT ANY TIME. It's just that some times are more cosmetically amenable than others. Now, the summer, is such a time.

Before I go any further, can I apologise to those of you who tried my autumn moss treatments described last year (click 'moss' link at side), but have found moss re-growing in their turf this year. It's my fault, not yours. I should have made things clearer. In case you are sick of hearing about moss and don't want to read further, here is a quick prognosis:

• keep zapping moss as soon as visible, any time of year
• rake out some of moss if it looks bad
• apply liquid lawn feed (usually all that is necessary)

All pests, diseases and disorders have one thing in common: They are all extremely resilient and enduring, able to resist the most adverse conditions and re-establish at appropriate times. The ways they do this is a fascinating study in itself - one which would teach we humans a thing or two, but this is for another day.

MOSS NEEDS REPEATED TREATMENTS
Consequently, moss is difficult if not impossible to eradicate AT ONE ATTEMPT; it has to be ground down over a period of time with REPEATED TREATMENTS. But hold on. I'm not talking about all the hard work you did to aerate and loosen your turf. I'm talking about another dose of ferrous sulphate in water.

NIP IT IN THE BUD
I'm sorry I didn't make clear that you need to watch the turf closely for signs of regeneration, then nip it in the bud. This is what I did with my lawn. The moss problem reduced significantly, right from the off. But I then wanted to change the conditions to eradicate it completely.

AUTUMN TURF TREATMENT HAS NOT BEEN WASTED
This is where the turf aeration and top-dressing comes in. It hasn't been wasted. And it's not even absolutely necessary to contain rampant moss - another dose of ferrous sulphate will do this.

As the battle continues, moss is contained to a smaller area of lawn, perhaps just the odd patch or two. This happens fairly quickly. So what I did then was apply ferrous sulphate with a hand sprayer; but if it had spread too far, I treated the whole lawn (this is what I did early last November). Having said this, however, always bear in mind that there will always be much more moss in a lawn than that which is visible. This always seems to be the case. So watch that it doesn't become rampant again once your back is turned.

TREATING SUMMER MOSS

MOSS USUALLY STOPS GROWTH IN SUMMER
Because moss usually thrives in wet conditions (some mosses thrive in dry ones), as the lawn surface dries, it dies back because, unlike the grass, it has no root structure to access water deeper in the turf. This is why you should never water a lawn too frequently with small doses. Water heavily at longer intervals (see last year's lawn posts). It gets the water deeper down for the grass roots, but allows the surface to dry.

HIGH NITROGEN FEEDS USUALLY KILL MOSS
After recent rainfall in parts of the UK, lawn recovery can be enhanced by applying a summer feed. Although this can incorporate a mosskiller (ferrous sulphate), it should not be necessary unless the weather (and turf) is very wet for prolonged periods. To give you some indication, I don't think I have ever used a summer lawn feed with mosskiller.

WHICH TYPE OF FEED
The choice is between granular or liquid feeds. (See 'Choosing A Lawn Feed')

Liquids
Liquids are ideal at this time (they can also contain ferrous sulphate mosskiller), because they soak the grass leaves. When wet, the feed is taken into the plant, so starts working almost immediately (granules take about 2 weeks). But there's another benefit. As they dry on the moss, it tends to be killed (due to plasmolysis).

Liquid feeds also have the benefit that they are more controllable, especially if the weather suddenly turns dry. All this was dealt with last year.

WHAT ABOUT THE UNSIGHTLY DEAD MOSS?
Mosskiller instructions and gardening programmes always advise removing the dead moss by raking. But this is hard work and is usually not necessary.
Many believe that this removal prevents the moss re-establishing from spores (moss's equivalent of seeds) left on the ground. This is not true. Only the heavier metal salts (such as mercuric chloride (no longer available)) will kill the spores (it also kills almost all your soil micro-organisms, as well).

Others say removal makes room for air and light to enter the turf. Well. Maybe it does. But lawn grass will almost always grow through it very quickly. And because moss is soft tissue, it soon breaks down in the turf (unless it's a dry summer, or the turf is very acid).

GIVE IT A LIGHT RAKING
I found that a compromise works well. Rake out some. But you don't need to be too thorough. And only do this if it looks unsightly. It's really determined by cosmetics.

JUST A RECAP

So, starting now, follow last year's moss posts through from beginning, just like last year. Otherwise:

• keep zapping moss as soon as visible, any time of year
• rake out some of moss if it looks bad
• apply liquid lawn feed
  

And, don't forget. KEEP NIPPING IT IN THE BUD. YOU WILL BE SURPRISED AT THE RESULTS.

Moss-Free Spring Lawn After Autumn Treatment

My lawn hasn't looked like this in spring for ages. No moss whatsoever. I'm really pleased. Although I fed it a couple of weeks ago, I have resisted cutting it till now to help root growth. Leaving the grass longer both provides more food for root growth and prevents stress. This last point has been apt this year; things are getting very dry.

Gave it a quick comb with the raker (scarified lightly at half walking pace)
to remove the dead grass. Quite a lot came out but it hardly showed. Great. Autumn moss treatment definitely pays dividends.

P.S. Don't throw your rakings away. They make an excellent soil conditioner and moisture retainer. We shall soon be digging them into the soil.

Glyphosate Safe On Moss On Flags

Glyphosate is normally used as a safe systemic weedkiller which is inactivated on contact with the soil. It is supposed to be very safe to all animals (including us) and can, apparently, be used around fish ponds without damaging the fish.

What I didn't know, however, is that it also works on moss - Moss on the flags that is, NOT ON THE LAWN.

Of course, it will work on the lawn, but because it is non-selective it would also kill the grass - and we don't want that (not after all the years I've spend keeping it alive!).

I always have a problem with moss growing on some shady flags, because the birds use it for nesting. And by the time they have finished, the season is nearly over. Consequently, moss builds up year by year.

WHAT ABOUT TEMPERATURE
As outlined elsewhere, glyphosate is extremely good on all sorts of weeds. However, it works best in warm weather, usually in late April or early May when the weeds are growing actively. Of course, the moss is growing now; so I have treated a small patch to see how it goes. About 8 hours of dry weather is needed so that it doesn't get washed off before it can be absorbed.

BEGINNERS NOTE:
'Tumbleweed' and 'Roundup' are trade names for glyphosate in the U.K. But you needn't use a brand name; you can use a cheaper generic brand. Look at the label, usually the front one. Glyphosate will be stated as the ACTIVE INGREDIENT, along with its strength. The cheapest way is to buy the concentrate, make it up yourself and apply with a hand sprayer (e.g. old kitchen cleaner spray).

ALWAYS USE RUBBER GLOVES WHEN USING WEEDKILLERS AND PESTICIDES, no matter how safe they are supposed to be - they can be absorbed through the skin!

No Moss In Lawn: Feeding Delayed

Following last autumn's treatment, then a single treatment with ferrous sulphate mosskiller in November, the lawn now seems to be for the first time completely free from moss.

AUTUMN TREATMENT
Of all the things I did last autumn, I think lowering the acidity by adding ground limestone had the most effect. I say this because this was the first time I had done it; I had been thinking of doing it for years, but always shied away on the grounds that it might make the turf susceptible to fusarium disease, and also might create a worm cast problem. So I did it in the end out of sheer desperation.

Thankfully, the news is good on both fronts:

• There seems to be less disease than usual
• There is only one worm cast since the treatment (I did get occasional ones before this)
  

DELAYED SPRING FEEDING
I usually feed with a spring feed with ferrous sulphate mosskiller at this time of year, but I came unstuck last year when the weather turned nasty. So I have decided to delay feeding a week or two longer.

Moss in Lawn

Spotted a strand of moss in the lawn two days ago, so treated whole lawn immediately with 20% ferrous sulphate at 1 ounce per gallon of water per 10 square yards (35grams per 5 litres per 8.5(approx) square metres) . First moss this autumn. Moss usually establishing strongly in mid August and, if left untreated, would be rampant by this time.

I feel liming (reduction of acidity) has improved things. Very tempting to give more lime to see if moss removed entirely. But because of disease risk, best take it gradually by adding no more than 35 grams per square metre (1 oz limestone per square yard) at one time.

As you can see, the damage is not too bad. Can tolerate this over winter. Because grass not cut short, it tends to hide any black stuff (dead moss). I haven't cut it since before it was aerated. As stated elsewhere, 'sulphate of iron' is ferrous sulphate (19%). Application by watering-can at the above rate should do the job.

Definitely worth looking very carefully for any signs of moss (there was so little in mine, I could hardly find the spot after leaving and returning) and killing it before it gets established and reproducing. This treatment should hold it at bay for a month or two. Should be well ahead by spring. Unless . . ..

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.

Dealing With Moss

Reply to comment:

'Can u please tell me that how can we treat this disease.....
By Acidity on Testing the Soil Acidity on 12/09/10 '

Thank you for your comment.

Moss control in my lawn has been covered in several posts throughout the year. I used to have a really bad problem, but after applying the treatments outlined it has almost disappeared. In fact, it hasn't made any appearance this year so far.

If you click the 'moss' link at the side, you will see some of the posts. But to give you an indication of the techniques, they are really concerned with the following:

• controlling acidity
• preventing waterlogging and creating aeration (spiking)
• starting treatment at an early stage
• chemical control with ferrous sulphate
• removal of dead moss by raking
• thatch control

The standard way to deal with moss is with a mosskiller such as ferrous sulphate. This can be bought commercially as 'Greenup'; it also sold as a component of lawn sand, which is used as a spring feed.

Now is a good time to start with moss control, if it is present in a lawn. Have a read of the posts and let me know if I can help you further.

Best wishes,

Jimini

Lawn Action in August

Reply to comment:

'What action do you take in August?
By Anonymous on Moss in Lawn on 25/08/10'


Thank you for your comment. As far as the lawn is concerned, if you look in the blog archives, you will see that I posted a 'Moss Alert' on 6th August which alerted readers to the dangers of moss getting hold at this time of year. If you look at the post, you should find links back to other lawn articles which will outline moss and other lawn jobs. Also, if you look at the categories at the side and click the 'lawn' link, you should find all the lawn posts.

There was also a lawn posting yesterday which was written before I read your comment.

The Lawn in August

August is in many ways a strange month, certainly as far as a lawn is concerned. Temperatures are still reasonably high, and provided there is sufficient moisture in the ground, growth should be quite strong. It is therefore a good opportunity for a lawn to recover from the hot often dry summer months (especially this year). High nitrogen (these should also contain some phosphates and potash (P and K)) feeds can be given up till the end of the month, which will really help the lawn recover.

However, there is also a downside. Overnight dews combined with high temperatures provide an ideal breeding ground for fungal diseases. You will see that I have had problems with 'Dollar Spot' disease (apart from the blight on the tomatoes). This has been largely dealt with by raking it out somewhat prematurely. This operation has been mostly successful, though there is still a little bit left. This disease is not fatal (it only affect the finer grasses, anyway); it merely disfigures the lawn for a while.

And of course, there is moss, the bane of my life (one of them). Warm dewy nights are also ideal for spore germination. Moss is sneaky and can suddenly appear, as if from nowhere, as I am sure you are well aware. So I really do advise you to be on the lookout for it.

I limed my lawn this summer (see 'Keeping it Sweet') to help with my moss problem. And, touch wood, this seems to have worked, at least so far. Usually I have had moss before now. But the lawn seems clear. Hope I haven't spoken too soon.

Removing acidity (by liming), and improving drainage, can each help tremendously with the moss problem (liming is best done early in January).

If you look back at the summer lawn posts, you will see that I spiked the lawn to aid water penetration (look under 'lawns', 'watering' and 'water conservation'). Water penetration can be prevented either by a thatch on the surface or by compacted dry soil beneath. Spiking, or pricking punctures the surface to allow the water through it.

A good technique is to go further than this and push a fork further down into the soil (as I did in the summer). If it is wiggled around, in the right conditions, it will break up compaction. But there is a downside: The soil needs to contain the right level of moisture, otherwise it can do more harm than good (this will be explained soon). Furthermore, because it breaks the root system, we need to be sure that the grass can recover quickly enough by growing new roots. For these reasons, I do not recommend deeper tining at this time (best to wait till further in September). Stick to pricking, spiking or shallow tining if you can.

If the soil is really hard - so hard that water just cannot penetrate (as it has been this year) - I push the fork deep into the soil just to make a hole, but do not wiggle it. This way, root damage is minimised, and the water has more chance to get deeper down to where it can begin wetting the lower levels.

The other thing which is good is Hollow Tining (provided the ground is not too hard), which I briefly touched on in a previous post.


If there is one thing I want to teach you about growing, more than any other, it's that we need to do things when the plant dictates, not the calendar. I know there are good arguments for doing things at the appropriate time. But nevertheless, this should be dictated by the plants. Times have changed. Seasons have changed. Methods and opportunities have changed. Equipment has changed. It's all changed from how it used to be years ago. We need to bear this in mind, yet still consider the wisdom from the past.

As the autumn progresses and the nights draw in further, the lawn detects this and changes its growth pattern from producing leaves to producing roots for next year. I have just given my lawn a feed which should be enough for leaf growth this year and give the grass a good start into the autumn when we can concentrate on the roots.

So, to sum up, make sure the drainage is good on your lawn and that water can penetrate down into the soil, ensuring any winter rains can get away without waterlogging the surface. Get on top of the moss, rake out any thatch and dead grass if necessary.

I hope this will be useful.

Best wishes,

Jimini

Moss Alert

This is the time of year (especially with the wet weather) when dormant moss spores sitting in the lawn spring to life and establish themselves unnoticed. By the time you realise moss is there, its removal will leave an usightly mess - and a much much bigger mess if you ignore it until next spring, as encouraged.

Best be aware and nip it in the bud as soon as you see any sign at all (get down close and look carefully). If moss is found, I suggest spraying full lawn with ferrous sulphate as we did earlier. You'll be amazed at just how much moss is actually there (its now black colour makes it stand out). But by treating it this early in the season it can be raked out, if necessary, and the turf will have time to recover before the winter. And you will have that lovely rich green colour from the iron salts.

If you're lucky and you don't have much thatch or dead grass, you might not even need to rake, not yet anyhow. The grass should soon cover up the dead moss which will just rot down. Never mind about the spores; as stated elsewhere, normal mosskillers do not kill them; there's nothing you can do about it.

Keeping it Sweet

Excessive thatch on a lawn can be caused by over-acidity on the surface. Acid rain, ammonium fertilizers, ferrous sulphate, and breakdown of old dead material all contribute to acidity. Whilst a certain amount is necessary (pH 5.5 to pH 6.0), too much acidity restricts the activity of the micro-organisms which break down the old thatch materials; it is also conducive to moss.

For the first time, have spread about 35 grams of limestone flour per square metre (1 oz per square yard) on dry lawn surface. Hope this will help reduce thatch without raking (which destroys the turf and leaves it open to water loss).

Note: Lime must be in the form of ground limestone (calcium carbonate, not the stuff they put on walls and houses), the finer the better. Although slower acting (can take 2 or 3 years), this is the safest way. Must be careful not to add too much, as this could make lawn disease-prone. Could do with some more rain now, to help the breakdown process.

Will be interesting to see how much moss develops this autumn. I used to use 'growmore' granules (7-7-7), which contains a proportion of calcium carbonate. I never seemed to have a moss problem then. However, I have since discovered that this might be a cause of thatch, not a cure (because it contains too much phosphorus). Just when I think I've found a solution. . ..

Moss in Lawn

Moss can look lovely in the right setting; it looks positively awful in the lawn, especially as it dries out and turns brown during the summer months.

If left untreated, it can quickly colonise a lawn, replacing the grass almost completely. This is especially a problem in damp shady conditions.

I don't think I need tell you what moss is. But here's something you might not know:
The time to tackle moss (if indeed you decide to do this) is not in the spring, as most growers suppose (and as most gardening books recommend). No. The time to tackle it is in early autumn (August in the UK) when it recommences growth during the warm dewy nights. At this time it can be nipped in the bud and kept under control.

This is not to say that it cannot be controlled in spring - it can. Modern moss killers will turn it black before your very eyes - literally. It can be killed in seconds. However, as you might be aware, killing it is not the problem; the problem is the unsightly mess that is left behind.

Gardening books tell us to rake this dead moss out immediately. Nothing wrong with this. But unfortunately it leaves a lawn devoid of grass, resembling the leftovers of a nuclear holocaust. And it can look this way for several months until the grass has had time to get going and fill in the bare patches.

Many gardeners think that raking the moss out in this way will prevent its re-establishment. I don't think this is true. I think just the opposite. Disturbing it too much will help spread the spores (the moss's equivalent of seeds) to other uninfected parts of the lawn. These will lie dormant till autumn.

It is supposed that moss killers kill these spores. Not true. As far as I know, only mercuric chloride (the old-fashioned moss killer, no longer available) will kill spores. Ferrous sulphate, the common moss killer, will not.

When we consider as well the enormous effort needed to rake a lawn efficiently, added to the above, I think there has to be a good case for leaving it alone.
This might sound horrific, but it is not so silly as it seems.

Since we cannot kill the spores and prevent re-infection, and since the moss dies out anyway in dry weather, what benefit is there in killing it off in the spring?

Provided it is not too unsightly, and that water can pass through it to the lawn, my suggestion is to leave it alone (and green) for now and concentrate on reviving the remaining grass so that it will be ready to take over as the warmer months approach, filling in as the moss dies back, and subsequently hiding its brown colour. This avoids the unsightly mess. It also saves us much time and effort whilst avoiding adding chemicals to the soil.

The moss will rot down in the turf as it dies back, leaving the grass. Then we can tackle it when it resumes growth in August. Hopefully, by that time we should have a decent lawn.

That's the theory, anyway. I have used this principle for several years. It has worked well for me. I hope it will work for you.