Soooo, you have a landrace Durban, crossed with unknowns?

If so, you no longer have a landrace, you have a hybrid. Crossing strains to get favorable traits from the parents.

Anywho, I'm not sure of the question. Depending on what it's crossed with, it sounds Sativa-ish. So, warmer temps, more light, less nutes, are generally in order for Sativas. But again, it depends on what it's crossed with.

 IBL's and Landraces are still just marijuana plants. Grow them like you would any top shelf bud.