Oh my goodness Karen I can't imagine having flooding like that! My house is on a hill so even when we get waterfalls (& have to sweep water out the front door) it doesn't wash my garden away. I'd be devastated!
I'm happy to see that your veggie garden is doing well! So far I've only harvested lettuce, kale & spinach. The tomatoes & melons just got planted.
Have you thought about retaining walls or seriously raised beds (2-3 feet tall)? A terraced garden perhaps? I just don't know how I'd cope with that much water. That just seems like an impossible situation. I do hope at least some of the flowers bloom well for you. Not sure what is up with the color changing plants but if the flood water changed the pH of your soil that might explain some of it.
