How much cleanup you must do will depend on how wet and rainy conditions are. Unless it rains and the petals become gummy or moldy, you won't need to clean them up. They will blow away or decompose. But If they are really piling up and are unsightly because they are showing mold, then definitely rake them and dispose of them off your property. Moldy blooms can harbor botrytis, a petal blight. My favorite lazy cleanup technique is to rake them onto the lawn the day the mow & blow guys come. Then it's all chopped up with the grass and goes into the compost.