During the winter your grass can become yellow due to stress and the harsh weather conditions. If you want to green up your lawn during this time of year normal fertiliser really isn’t all that good for the grass while it is in its mostly dormant state.
The best products to add to your lawn are iron, usually with sulphate of iron, and also magnesium this is best done using Epsom salts. You can get these in most garden centres and Epsom salts are also available in pharmacists but this can be quite expensive.
To do this you will need a garden sprayer and a set of kitchen scales. Measure your lawn and weigh out 15 grams of sulphate of iron and 15 grams of Epsom salt for every square metre of lawn put this in a bucket and dissolve it in as much water is as you can I usually try to go for 15 litres of water for every 50 square metres of lawn, this is a backpack sprayer full. Don’t get any grains in the sprayer as this may clog your nozzle.
Diluting it means it will be applied more evenly and stop patching, walk over the lawn evenly going along then up and down the lawn until all the measured amount of iron and Epsom salts are on the lawn. In a week or two you will have a much greener healthier looking lawn.
Things to be aware of are these; more is not better here if you add more iron than the recommendation it will turn any moss in your lawn black which is not a bad thing for the lawn but wont look good over the winter which is the thing we are trying to achieve. Also iron stains stone and concrete very easily leaving rust marks which are a pain to get rid of so be careful around paths etc and if you do get it on there wash it off immediately with loads of water.