In a container,I'd use something like the 5-1-1 mix.The purpose of it,is to be used without any dirt,which will clog the draining and air movement process in the rooting area.
Gravel in the bottom will not do any good.A wick can be placed in the bottom and led out of a drain hole to help.
I also feel and have a moisture meter.Also after watering,lift the pot up and get a sense of what it is when fully watered.By knowing this,it will be easier to tell to water by weight.
Are these two separate trees and where is your location? Brady