Windowsill Herbs Need Six Hours of Direct Sun or Supplemental Grow Light

… more less Basil, rosemary and thyme want 6+ hours of direct sun or a DLI of about 12–17 mol m⁻² d⁻¹. A December windowsill in London or Hobart's June gives far less, so a light 15–30 cm above leaves for 12–16 h fills the gap.