I've covered everything I can in anticipation of the coming cold event (36 hrs below freezing, low of 20F). I've used 1000 sq ft of frost cloth covering large shrubs and palms, but dont have enough to cover my raised beds. I have drip irrigation and microsprinklers in all my raised beds. Does anyone have an informed opinion on whether its better to leave it on or off overnight from the standpoint of providing warmth. I'm talking about doing this for relatively tall perennials (Hibiscus, Angelwing Jasmine, etc)where the water will only contact the base of the plant. I wouldnt contemplate doing it on low growing annuals like pansies or snapdragons.