I am growing some of the tropical plants from Australia-Deplanchea, Melicope, Tecomanthe vines, etc. I am wondering, can these plants from tropical Australia be fertilized with a fertilizer that has a higher level of Phosphorous? Or are they sensitive to it like the more western species? Or is it just the Protea- type that are sensitive to P? Or is it more complicated than that? It is hard to find many Australian plants, with a few exceptions in Florida.
I think it's safest to stick with low phosphorus levels for Australian natives. Like with everything else, it's never simple. I want to get some Tecomanthe but there doesn't seem to be any in nurseries around here. I've seen (photographed) Deplanchea flowering out in the wild, but that's another one that I never see in nurseries.
I have 2 Tecomanthe, maybe 3. one of which has white flowers instead of the usual pink. It got very large last summer so am hoping for the best. My Deplanchea is about 10 feet (2.5 m) and has never flowered. I have seen them flower at 2 feet so don't know what is going on, Talked to a friend in the rainforests of Queesland and he said the only ones you need to be careful with P are the various gerera from the Proteacea family, Grevillea, Bankia, etc.
I'll just have to keep looking for some Tecomanthe. The Deplanchea needs sun. They're a marginal rainforest plant, in that they usually grow on the margins where they're in a lot of sun.
For definite the Proteaceae but there are quite a lot that are rainforest plants as well. I just err on the side of caution and keep the phosphorus levels on the low side. I think my biggest problem is keeping the potassium and magnesium levels up. That seems to be a common issue in high rainfall areas.
The person in the rainforest, is that at Cow bay, in the Daintree?