This paper explores the semantic motivation of English phrasal verbs with the particle out whose constituent verb refers to processes and activities performed by or to plants and their prefixed Serbian counterparts with the prefixes iz-, s- and raz-. The cognitive approach to the semantics of phrasal verbs and prefixes is employed, which entails observing their meaning through the notions of conceptualisation, image-schematic structuring and spatial schematisation. It is shown that there is a high degree of correspondence in the concrete and abstract senses of the contrasted English and Serbian lexemes owing to the same spatial configurations which structure the constituent English and Serbian satellites (the particle out and the prefixes iz-, s- and raz-, respectively). Additionally, various conceptual metaphors stemming from the domain of PLANTS, inherent in the constituent verb, play a prominent role in the extension of the phrasal and prefixed verb meaning in both languages. The conclusion underlines the benefits of using the cognitive semantic approach in the contrastive studies of particles and prefixes.