In this paper, we address the emergence of horticultural practice, agents, spaces and institutions in the two urban settings of Lisbon and Porto, in Portugal, during the second half of the nineteenth century. We do so by following the networking activities of two players: the self-made horticulturist and entrepreneur José Marques Loureiro, who created, in Porto, a commercial horticultural establishment and founded theJournal of Practical Horticulture; and the agronomist Francisco Simões Margiochi, head of the gardens and green grounds department of the municipality, who created the first course on gardening and horticulture, and founded the Royal Horticultural Society, both in Lisbon. Their joint activities were aimed at establishing horticulture as an applied science and to cater simultaneously to an extended audience of citizens. They enable us to enrich the narratives on the emergence and development of horticulture in Europe by calling attention to the participation in circulatory extended networks of actors who are often absent from these accounts. Additionally, they allow a comparative assessment of the outcome of their actions at the national level, and to understand their results in terms consonant with recent historiographical trends on the co-construction of centres and peripheries. Abbreviations:AML – Arquivo Municipal de Lisboa (Municipal Archive of Lisbon).; ANTT – Arquivo Nacional da Torre do Tombo (National Archives at Torre do Tombo).; AHCPL – Arquivo Histórico da Casa Pia de Lisboa (Historical Archive of the Casa Pia of Lisbon).;JHP – Jornal de Horticultura Practica(Journal of Practical Horticulture). Online at:http://www.fc.up.pt/fa/?p=nav&f=html.fbib-Periodico-oa&item=378;BSNHP-Boletim da Sociedade Nacional de Horticultura de Portugal(Bulletin of the National Society of Horticulture of Portugal). [ABSTRACT FROM AUTHOR]