Fertilisers must be applied with caution, preferably by fertigation using formulae suited to the soil. Protea and leucadendron are adapted to well drained, nutrient-poor soils and winter rainfall. They are vulnerable to Phytophthora root rot and fungal leaf diseases associated with summer rains. Waratahs, by contrast, are adapted to summer rainfalls. They are less vulnerable to phosphorus toxicity, but they do require deep, free draining soils.
Proteas are more vulnerable to frost than leucadendron and waratah.
Leucadendron colour develops better in cooler climates. All commercial varieties do better in acid rather than alkaline soils, the ideal being a pH of 5 6. There are about 20 commercial varieties, not all of which will do well at any particular site. It is important to choose target crops with care, and put in a trial plantation in parallel with the target planting so failures can be replaced with cultivars more likely to succeed. Other cultivars and hybrids are available that might do better at your site.