Watering plants in the midday sun scorches the leaves (water droplets focus sunlight like lenses).
Refuted
Watering in the midday sun won't scorch your leaves — droplets don't focus light onto the leaf, and they evaporate before they could. Water whenever the plant needs it; morning or evening just wastes less to evaporation.
What is actually known
Water droplets on a leaf do not focus sunlight into a burn. A droplet's focal point sits below the leaf surface, not on it, and on a flat leaf the droplet evaporates long before it could do damage — controlled trials find no scorching on smooth leaves. (Densely hairy leaves that hold a droplet above the surface are a rare theoretical exception, not the everyday lawn-and-veg case.) The real reason to prefer morning or evening watering is that far less is lost to evaporation in the heat of the day — an efficiency point, not a scorch risk.
Evidence: not yet confirmed against its 1 source.
what this rests on - one pointer
droplet focal point is below the leaf and evaporation precedes damage; controlled leaf-scorch trials; horticulture-myth literature
When would that grow at your place? →