I tend to kill plants when I have them I either over water them or under water them. For that reason I never have them long. I tried some sunflowers earlier this year when all of us from the forums were planting them but I didn't have much luck. I got a few to bloom and they withered and died shortly after. I've thought about trying some easier to care for plants such as the marble queens you own. Might give that a try and see how it goes. Yours look very happy and well cared for.