Pour the sugar and the water into a pot and bring it to a boil. Be careful with it; hot sugar water is dangerous since the boiling point is a lot higher than water.
Once the sugar as fully dissolved take the pot off the hot plate, add the citric acid and let it cool down just a little bit while you assemble your other ingredients. It is important because the liquid is so hot at this stage that it could crack your jars.
Add the cleaned petals and juice of one lemon to a big jar or split it among smaller jars.
Pour the hot sugary water over your flowers and seal the jars immediately. Store in a dark and cool place for 5-7 days, gently shake the mixture every day.
After 5-7 days, strain the liquid through a mesh sieve and discard the flowers. Store the liquid in clean bottles or freeze it in an appropriate container.
To enjoy this lovely drink, add 3tbsp cordial to 300ml (1 1/4 cups) of water. If you prefer it sweeter, you can add more. The recipe is enough for around 45 glasses.Freeze the cordial in ice cube trays and store the cubes in a container for easy portioning.