Pick the rose petals just before starting, so they're fresh. Boil 6 pints water and pour over all ingredients except yeast and pectic enzyme, stirring gently to dissolve sugar. Cover with cloth or plastic wrap and set in warm place for 24 hours. Add pectic enzyme, yeast and half remaining water. Set aside until vigorous fermentation subsides (7-10 days), stirring daily. Do not exceed 10 days. Strain liqueur into secondary fermentation vessel, top up to neck with water, and fit fermentation trap. Rack after 30 days, then again after additional 30 days. Bottle when clear and store in dark, cool place. It will be fit to drink after 6 months, but will improve enormously after a year.