It is not a factor of 'sap' being too high in your Azaleas and Fire Bushes, it is that the temperatures are too high and that makes it very difficult to transplant without damage or plant loss. It would be better to move Azaleas while they are dormant in the late Winter. And most Fire Bushes are not perennial so they may not survive the Winter temperatures unless you live in Southern Texas or some place where you have rare freezing temperatures.

Thanks for your inquiry.

Happy Gardening!
The PlantMaster