Being in the Sandhills is a challenge. The weather patterns changing does not help. We just upgraded from a zone 7 to an 8....This so far has worked for me, it does sound weird, but it works. I use plastic bags, the ones from food shopping. I dig the hole much larger than needed, line with these crumpled up bags, cover with the original sand & then add compost & the plant. I'm not worried about root rot as the roots seem to find their way thru just fine. Plus less leeching of nutrients thru the sand. I have only been here for 5-6 years now so I don't know long term...But for now it seems to work.

Also on the cheap side are those heavy plastic storage containers at Walmart & such. I drill several holes in the bottom, then completely bury the container. It's not hard because it's all sand. Not a rock or pebble to be found! This is also good if you have Voles! {little, evil, hungry,monsters!}