Carefully rinse the rose petals and snip off white bases. Place the petals in a bowl and gently mix in half the sugar. Cover the bowl and leave overnight.
The next day, put the remaining sugar and the water on to boil, stirring to dissolve the sugar. Add the lemon juice and boil for a further 5 minutes.
Leave aside to cool until just warm, then stir in the rose petals. Put back