Kris, sory to see the loss of your "Queen". I have about 10 I started from seed 2 years ago.
I have never kept them in shade, but rather in direct sunlight. They have endured 2 summers now and are looking very healthy.
I watered them heavily twice a week, fertilized in April, July, and October with Slow release brand.
I also threw about 50g of Epsons Salt (Magnesium Sulphate) into the top soil and mixed it in.
The medium I used was regular potting mix. I think it may keep the soil somewhat more moist than your river sand.
They grow well here. I've seen some growing in redish clay near one of our golf courses.
I plan to plant them in spring next year.