Making your own lawn dye is at best a temporary solution to a long-term problem. Patchy grass that grows poorly usually happens because of problems in the underlying soil or lack of moisture and light. If you need to dress up your lawn to help your home's curb appeal or just want it to look better for a party, you can easily make and apply your own lawn dye using a few simple ingredients.
Watch weather reports and choose a clear, windless day with no predicted rain for several days before applying homemade lawn dye. Measure the area of lawn you want to dye by multiplying the length of the area by its width.
Put on rubber gloves to avoid staining your hands. Pour 473 ml (16 oz) of liquid lawn fertiliser in a 22.5 litre (5 gallon) bucket. Add 2.27 kg (5 lb) magnesium sulphate gradually, stirring with the stick to dissolve it into the fertiliser. The magnesium sulphate and fertiliser will boost help boost the green colour of grass leaves fairly quickly -- naturally -- and stimulate growth.
Add 56.7 g (2 oz) of green food colouring to the mix, stirring continuously. Pour the mixture into the sprayer attachment and connect it to your garden hose.
Set the hose on its widest spray setting and spray the lawn evenly, starting at a far corner and working across. Disconnect and refill the sprayer as necessary. This recipe will cover an area of 93 square metres (1,000 square feet), so mix more batches of dye as needed. Finish with a light watering, and let dry.
A variety of commercial dyes or "lawn paints" are available, many lasting up to three months. Choose the right type of grass for your climate and light conditions and follow proper mowing, watering and fertilising procedures to grow a healthy lawn that doesn't need dyeing.
Don't let pets or small children play on a newly-dyed lawn. While it isn't harmful, the dye may stain paws and bare skin, especially if weather conditions are humid.