Grandad’s Recipe For Lawn Sand

The Fact Sheet for this segment needs a little editing… 

To read the original go to the ABC Website at:

Grandad, Dad, yours truly and our weed-free lawn
Grandad, Dad, me and our weed-free rye grass lawn

After having recommended this recipe without any hitches for over twenty five years I discovered it has one weakness. In Australia sulphate of potash and sulphate of ammonia are sometimes sold in granular form. Either check they’re in powdered form before buying or put a mortar and pestle to work before using this recipe…

Presenter: Jerry Coleby-Williams [16/07/2005]

Jerry’s recipe for a weed free lawn.

At this time of year, broad leaf weeds or flat weeds in lawns can be a real nuisance. Many years ago, when I was living in London, my grandfather came up with a secret lawn sand recipe. It’s simple, cheap, effective and safe to use.
Buy the ingredients for Grandad’s lawn sand at any hardware store or garden centre. The ingredients include: dry washed sand,  sulphate of potash (crystals) and iron sulphate (crystals). You can substitute the sulphate of potash with sulphate of ammonia. 

It’s essential that the sulphate of ammonia, sulphate of potash and iron sulphate are used in powdered form, not the granular form. Why? Because crystals coat the weed leaves. Granules harmlessly roll off the foliage – a waste of time and money.

Use a plastic bucket and a plastic measuring container because these can be washed after use. Simply mix the ingredients in equal proportions. So put in one cup of washed sand, one cup of the sulphate of potash and one cup of the iron sulphate, and mix these up immediately.

It’s important to use exactly what you make because it doesn’t store well. If it soaks up any humidity, it will become rock solid. Also wear gloves because the iron sulphate can make your hands rusty.

Grandad’s lawn sand is fantastic for controlling a variety of weeds in the lawn. It’s especially good for attacking cudweed, bindii, white clover, cats ear and plantain. Sprinkle by hand aiming directly at the weeds. There’s no need to cover the entire lawn. It’s best to apply just before sunset so that dew fall will activate the mix, or lightly sprinkle the treated weeds to damp them down to start the process. To control all weeds repeat this operation every other week.

Remember lawn sand won’t kill narrow leaved weeds like onion weed, winter grass or nutgrass, or waxy leaved weeds like oxalis or onion weed. If the mix comes in contact with flowers or footpaths, wash it off with water immediately because iron sulphate can stain. Keep a watering can nearby when applying to rinse spills off paths, etc.

If pets or children want to use the garden, water the lawn sand in the following morning. As soon as it’s dry, it’s safe for them to go into the garden. Iron sulphate can stain clothes and skin, so wear thin latex gloves. The sulphate of ammonia is basically a nitrogen fertiliser, sulphate of potash supplements potassium and the iron sulphate is a tonic that provides iron to plants.

These are chemical fertilisers which in this case are used to act as herbicides. Rain and irrigation after they have done their job will disperse and dilute them and they then act as fertiliser.

The objective is to complete the task in mid-winter, particularly in eastern and southern Australia. This prevents the weeds setting seed and starting another generation. The end result to aim for is a lush, thick sward of grass that helps to suppress weeds.

Jerry Coleby-Williams
3rd August 2006


4 Comments Add yours

  1. Robyn Alexander says:

    Is the lawn sand recipe safe with Buffalo grass?
    We laid a new Buffalo turf 6 years ago and it has been full of every weed imaginable ever since.
    Robyn A

    1. Robyn
      This recipe works only on flatweeds as mentioned. Use 2/3 strength.

  2. Erica says:

    This sounds like a fantastic alternative to those nasty weed and feed solutions! I recently bought a house with a backyard that’s more dandelion that grass. I valiantly had a go at manually removing the weeds, but only got through a few square metres before admitting defeat. Is this lawn sand suitable to get the dandelion under control and help promote grass growth, in addition to occasional forking? If so, is it ok to be treating the lawn now, or should I just mow regularly to keep the flowers at bay and commence treatment in the cooler months?

    Thanks in advance.

    1. Dandelions are edible and a good source of Vitamin K. Why not strike a balance?

      Jerry Coleby-Williams’ Facebook page and website are followed by 45 countries. He answers between 8,000 to 10,000 gardening questions free each year. He answers single gardening questions only.

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