Sclerotinia diseases, including white mould in lentils and stem rot in canola, are becoming significant challenges for broadacre farming in southern Australia. These diseases target multiple plant parts—such as leaves, stems, pods, and flowers. The pathogen forms black sclerotia, resilient resting structures that remain in the soil for 5–7 years. These diseases cause yield losses and grain quality issues due to contamination with sclerotes. Despite its increasing prevalence, there is limited information on the morphological characteristics of Sclerotinia isolates and how to differentiate them from similar fungal species in laboratory settings. The primary species responsible for these diseases in pulse and canola crops are Sclerotinia sclerotiorum and S. trifoliorum. This study assessed seven molecularly identified isolates of these two species, collected from lentil and canola crops, across six broadacre cropping regions in South Australia. The isolates were cultured on Potato Dextrose Agar (PDA) in small Petri dishes (diameter: 55 mm), and their mycelial growth, sclerotial formation, size, and distribution were documented over a period of more than a month, with observations commencing at four days after plating (DAP). All isolates, except S. trifoliorum, exhibited rapid mycelial growth, reaching the edge of the plate by 6DAP. Initial sclerotial formation was observed at 6DAP in most isolates; however, their distribution patterns varied. Some isolates formed sclerotia along the plate edges, others distributed them across the plate, and some exhibited both patterns. S. trifoliorum first developed sclerotia on the initial plug, with limited distribution across the plate in later assessments. These distinct sclerotial formation patterns remained consistent across six replicates. Sclerotial size also varied among isolates, with S. trifoliorum producing larger but fewer sclerotia compared to S. sclerotiorum. Furthermore, mycelial colony morphology in S. sclerotiorum exhibited notable variation, including white powdery, white smooth, light grey, dark grey, and white colonies with white specks, all of which were consistent across replicates. These findings enhance our understanding of the morphological diversity and growth behaviour of Sclerotinia isolates on artificial media. The observed sclerotial formation patterns may also provide insights into species distribution and survival in the field. This study offers valuable diagnostic characteristics that can aid researchers in distinguishing Sclerotinia isolates from other fungi in laboratory cultures.