Phytophthora species are important plant pathogens especially due to their ability to invade and change ecosystems. However, information regarding their diversity and distribution is not available in many parts of the world. In these areas, surveys of botanical gardens can provide opportunities to detect novel plant-microbe interactions on both indigenous and exotic plants. Three botanical gardens and one historical urban garden in the Western Cape Province of South Africa were surveyed to establish baseline information of Phytophthora species diversity in the Cape Floristic Region. Eight described species (P. amnicola, P. asparagi, P. capensis, P. cinnamomi, P. chlamydospora, P. lacustris, P. multivora and P. tropicalis), the known but as yet unnamed P. sp. emzansi and 3 putative hybrids were recovered. Forty eight of 103 samples collected were positive for Phytophthora species and P multivora was the most frequently isolated species. Three species (P. amnicola, P. asparagi and P. tropicalis) had not previously been reported in South Africa, although hybrid progeny of P. amincola had been found in two previous studies. These results highlight the value of botanical gardens as areas for baseline data collection and early warning systems.