This is how to make the 'plant' I copied it from another site but it's the same as I used to do.
1/2 oz dried yeast
1/2 pint water
sugar
ground ginger
juice of 2 lemons
Put the yeast into a jar, add the water, 2 teaspoons sugar and 2 teaspoons ground ginger and mix well. Cover the jar with a lid or clingfilm. Each day for 7 days add 1 teaspoon sugar and 1 teaspoon ground ginger. Finally, strain the mixture, add the lemon juice to the liquid and reserve the sediment. The liquid is now ready to use. For future use, keep the sediment and divide equally between 2 jars. To each jar add 1/2 pint water, 2 teaspoons sugar and 2 teaspoons ginger and proceed the process all over again, as previously.