I agree with @past times with mold issues. it is sort of relative to the time you water them in relation to sunrise however. weather you are on the coast or inland plays a part in it too. If my schedule dictated that I was doing a water only watering I would do it shortly before sunrise, if my schedule dictated that I was doing a "nute" watering I would do it well before sunrise so the water could carry the nutes deeper and wider to penetrate all or nearly all of my root structure. Mold is a bitch hands down! however by the time a mold spore lands absorbs the necessary moisture matures releases more spores and multiplies within about 4-5 hours of sun between 10am and 5pm the mold should be a thing of the past. "in my experience and opinion"