A full-sun species must not be placed in ground the gardener has marked as shaded.
Well established · costly if ignored → warn
How it works
Photosynthesis. A crop whose light minimum is full sun is below that minimum in shade and underperforms. Declared exposure — a wall, fence, or building the engine cannot see — distinct from the computed neighbour-shadow.
What to do about it
Plant it somewhere you have not marked shaded, or use that ground for a species whose light minimum is part sun.
The evidence
Evidence: settled without a trial - photosynthesis.