Marseillais

Basil commonly develops downy mildew (often first seen as yellow patches on upper leaves with gray-purple growth on the underside). Improve airflow by spacing plants and watering only at the soil line, then remove badly infected leaves early to slow spread. If mildew keeps recurring, consider switching to a resistant growing bed and avoid dense, wet foliage conditions—basil is very sensitive to persistent leaf wetness.

Harvest once plants are about 6–8 inches tall and have formed several sets of true leaves, typically around 45 days to maturity. For best regrowth, pinch or cut stems just above a leaf pair (at a node), taking no more than about one-third of the plant at a time. Stop harvest if flowering starts to show heavily, because flavor declines as Ocimum basilicum shifts energy from leaves to blooms.