Sunday 15 September 2013

Can I use general compound fertilizer on my lawn?

Yes you can.

One of the better bits of my lawn
Essentially there is no difference between a lawn fertilizer and a normal fertilizer. If your fertilizer is suitable for general purpose use in your garden it is suitable for your lawn. A granular fertilizer is no more or less likely to scorch than normal rapid release lawn fertilizer. Scorch is easily avoided by applying fertilizer immediately before reasonably heavy rain.
Should I use three-in-one?
The ‘rest of the world’ seems to use this combination of fertilizer, moss killer and weedkiller. Not me. The moss killer is usually iron sulphate and is itself a valuable lawn nutrient. I prefer to fertilize, moss kill or weed kill as a separate operation where and when and if I need to. Using three in one is perfectly sound practice but count me out. 
Do I need to use a fertilizer spreader?
No. It might be convenient for professionals to use a high quality spreader on a large scale but in the home garden with a little practice you can spread very evenly. Sometimes a badly adjusted spreader can cause more scorching than hand spreading! I tend to rather energetically fling my fertilizer. This would be inappropriate with ‘three in one’ as any flying on the borders might damage the plants!
How often should I fertilize my lawn and how much should I use?
This is a little beyond the scope of my article today. Once a year in Spring will be enough for most people although there is some merit in applying smaller doses but more often. If you box off your mowings thereby taking nutrients away there will be more need to fertilize. I mulch mow and take the unfashionable view that too much nutrient means much more mowing! For the record I applied 15gm/sq.meter of 20:10:10 agricultural fertilizer last month. It was my first fertilizer application in two years.

Which fertilizer should I use to feed my lawn?

‘Three in one’ purchased at a garden centre is relatively expensive but for a small lawn lawn the high cost is probably insignificant, For a large lawn the cost can be considerable. I have previously written about buying a 25kg bag of general fertilizer and using it generally! If you have a very big lawn you can achieve the same economy of scale by buying 25kg bags of sports turf fertilizer from a professional horticultural supplier. (Do not be persuaded to buy their amateur products, some suppliers on the net  have an expensive amateur section. Your money is as good as that of any professional!)
I have prepared a table of the relative costs of fertilizers you might sensibly use on your lawn, I have related the rate of application to the one recommended on a packet of ‘three-in-one’ that I examined at a garden centre. I have adjusted the rate of application of each fertilizer to provide the same amount of the most significant nutrient, nitrogen to that of the garden centre product. This will often in practice mean that more phosphate and potash will be provided by the fertilizer than from a normal spring/summer lawn fertilizer. For my sandy soil this suits me fine.
I have assumed for my calculation that you have sought out 25kg bags at a keen price. My figures are heavily rounded. 

Cost of fertilizer for a 1000 square meter of lawn

20:10:10                     20gm/sq.m      £20  
sulphate of ammonia  20gm/sq.m      £25
13:13:20                     30gm/sq.m      £30        
Yaramila complex       30gm/sq.m      £35
Professional sports turf fertilizer         £35
Growmore                  60gm/sq.m       £45
Gardencentre 3 in 1   30gm/sq.m      £100

The 13:13:20 was the general fertilizer recently applied at 12.5gm/sq.m by my expert friend Peter Williams.
I sometimes recommend sulphate of ammonia even though it does not contain phosphate and potash. On some soils it’s sulphur content may be very beneficial.
The garden centre ‘three in one’ was for sale in 7kg bags at £20. Its analysis was 14:2:4
Yaramila complex is the complete all nutrient fertilizer I generally use and it’s NPK content is 12:11:18.

A small trial.
In the interests of bloggery I added a few variations to my fertilizer application. Most of the lawn was fed in mid August with 20:10:10 at 15 gram per square meter (a very low rate but suitable for late summer). For a hundred square meters I doubled this amount and for a further hundred square meter trebled it. The anticipated rain arrived and there was zero scorching on all treatments. Unfortunately it then turned very dry and I cannot therefore show you pictures of an amazing green lawn! I think I can look forward to more benefits of the nutrients when it turns wet. The lawn has been improved by all the three rates of application with at the present time little discernible difference between the three rates. There has been a distinct increase in the need for mowing!
It is too late now in mid September to apply the high levels of nitrogen given by the rates of application in the table. I would not use 20:10:10 until March although low rates of an even balanced fertilizer like growmore would be alright. I think for most lawns in the UK autumn fertilization is of limited value.

Investigating scorching
A few days after fertilizing and when it had turned dry I marked out two squares of one square meter each and applied 20:10:10 and Yaramila complex both at the very high rates of sixty gram per square meter. This was deliberately done when the surface was dry and rain was not anticipated. It was a very hot spell and it did not rain for four days.The August dews were heavy. I imagine dews in the absence of rain are likely to increase the danger of scorching. You can see from the picture that the 20:10:10 did scorch.The Yaramila did not. Although the scorch has now grown out - after a month - and the grass is again green my demonstration does show that the rapid release of nitrogen from 20:10:10 can cause a problem. (I recently described it as lethal in inexperienced hands). Although the Yaramila would have also added a lot of nitrogen  it would seem that its formulation does release its nutrients more gently.

A very high rate of fertilizer

The high nitrate in a heavy dose of 20:10:10 did scorch

The two dark squares are one month after applying heavy doses of yaramila and 20:10:10.

Supplementary notes for lawn nerds
I was prompted to feed my lawn because patches of red thread disease had appeared and was getting worse with heavy autumn dew and very dry soil. This is a disease of underfed closely cut lawns. On the other hand beware using excessive nitrogen rich lawn fertilizer as this predisposes the grass to a worse infection, fusarium! You can’t win!

Red thread disease. Now, four weeks later we have had a period of wet weather. I am pleased to report the fine grasses are making strong new growth
I have ignored in this review the use of much more expensive slow release fertilizers which can give a lovely green sward for very long periods. 

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  1. So are you ab advocate of a closely cut lawn? It does seem that many people prefer short brown lawns to the longer green variety.

    1. You are quite right to chastise me Sue! I don't usually go to the closest cut on my rotary mower but with open day coming up I had! I blame Brenda for wanting it short! I always blame Brenda when something goes wrong as you will have noticed! I have now reverted to a longer cut for the winter. Lawns don't have to go brown with a short cut as long as they are cut frequently.
      Thanks for the kick up the backside Sue

    2. Anytime Roger :) By brown with relation to my neighbours grass I mean scratching most of the grass off down to soil level!!!

  2. My lawn, once installed as sod, was beautiful and deeply green. Now, it is nothing but weeds, so fertilizer is not the answer for it. I would be growing bigger, better weeds! Plus my neighbors are not too happy that I do little lawn maintenance. They spray and spray but after awhile, their lawns get thin and anemic looking. Seems there is no real trick to keeping the grass really green with all those big Norway Maples sucking up the nutrients and water. You wrote a pretty good article for lawn owners, very informative.

    1. Thanks Donna for your interesting comments. I think you often grow different grasses in the States but I think you are up in Niagara where it is cooler like here.
      I know you are not into spraying and in actual fact I much appreciate ecological lawns although this is not very apparent from my post! As Sue Garrett suggests above cutting the grass higher helps where there is drought conditions as under your maples.
      As I write I am sitting in Brenda's son's garden in Gex, France and am looking out on a weedy, er I mean ecological lawn and it looks really nice!

    2. Ps garden walker and talker I forgot to mention for the benefit of other readers that your blog always has the most fantastic pictures!

  3. Where can I purchase Yaramila complex to give my lawn a treat? It is in terrible conditions, moss and little grass, so I will be feeding it with sulphate of lime shortly, then later in the warm weather I thought a feed of Yaramila complex would be beneficial but ma having difficulty in locating a source. All (hopefully) I will need to do then is fill in the dents and tracks made by the people removing a large tree from the edge of the lawn. I must say that I have found you information informative and entertaining, though I don't believe you do any gardening, where would you find the time?

    1. Its a familiar problem I checked on Amazon and e bay and it was all the amateur stuff. I googled yaramila and found plenty of suppliers such as Munroes who were a lot cheaper than my local supplier but I expect there will be a hefty delivery charge for the 25kg bags. It is best to suss out a local ‘trade horticultural sundries supplier’ - I use East Riding Horticulture and collect personally. A local nurseryman splits bags and sells it to his customers,with appropriate warnings that it is twice as strong as growmore and misused will kill your plants!
      It’s worth pointing out that some local trade suppliers have in stock other similar commercial fertilisers from their own suppliers which are just as good. If East Riding were to switch suppliers, for convenience so would I.

  4. In North America, a lot of lawn fertilizer is now supplied without phosphorus. Sometimes it is a result of a law banning it, and sometimes a voluntary decision. The reality is that most lawns in N.A. do not need more P.

    In the past I hardly every fertilized the lawn. I did get weeds and spot sprayed for them. A few years ago Ontario banned all 'good' weed control products so I have started fertilizing to try and stay ahead of the weeds. I only apply nitrogen, and this year started using Urea (45,0,0). You have to spread it thin, but it works like a charm.

  5. Although both laws are frighteningly intrusive examples of the nanny state (Thought that was our problem and you were the land of the free- with all those guns!) the first ban on fertilisers does have a degree of logic. What does Ontario do to control its noxious weed - our equivalent might be ragwort - without MCPA or 24D?
    Surely your excellent urea also makes your weeds grow!
    As a fellow none follower of fashion you might be interested to hear that my January application of N (See 'fertiliser in Winter) seems to have had a beneficial effect on my lawn throughout this season. It gets recycled as I do not remove mowings
    I remember when we took the students to Holland thirty years ago and they had banned herbicides for amenity use (but NOT for food crops in agriculture) the local parks department used their old stock and sprayed very early in the morning!


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