Many household gardeners accumulate considerable knowledge of plant biology through a range of informal learning sources. This knowledge seldom relates to school biology and is driven by interest, keen motivation and what is termed here "vital relevance." A small opportunity sample of 12 gardeners (6 M, 6 F) is interviewed in terms of their knowledge of plant biology and their motives for learning. They are largely self-educated, their knowledge is quite specific though piecemeal and their motivation has a strong affective dimension.