You covered a lot of issues so I will address them as you mentioned them: "The main problem, though, is that they turn a very sickly shade of green in the late winter; they seem to darken to a more normal shade after I fertilize with Hollytone in the spring. Basically I am unsure whether the color is 100% a nutrition issue, or whether (as seems more likely) sun stress is contributing, too. I haven't tested my soil yet and need to...anyway, its composition is EXTREMELY sandy and probably is deficient in easily-leached out minerals/elements. I also ought to know my soil pH and I don't...Lavender grows very well in the same area, though, and I know it likes an alkaline soil. That's not good for rhodos, I know." I think your rhododendron is living from Hollytone to Hollytone and due to the sand, nutrients are leaching out A uniformly pale green is a lack of nitrogen. I would recommend replanting with a good soil mix of high humus acidic soil. Don't fertilize after the spring since that causes other problems. "My question is, would it help or hinder my rhodos if I started using a richer media as a mulch? I'm thinking composted cow manure, which I have a lot of. Is damage from overfeeding likely with rhodos? I have no experience with aluminum sulfate, but would topdressing with this help with the pH issue that I think is likely?" Several really bad ideas. Don't use cow manure or other manure as mulch. Aluminum sulfate kills rhododendrons and azaleas. It is good for hydrangeas but kills most other plants if used repeatedly. Powdered sulfur is the best for lowering the pH and it lasts. "I also am wondering about using a foliar spray containing iron and/or magnesium to help them green up. Is that a good idea, do you think?" The chelated iron foliar sprays will make it look better, but you need to fix he soil. "Please help me. I know I goofed by planting these here, but the funny thing is, they ALMOST do well in this location. If only the baby shade trees planted in the front yard in front of the rhodos would hurry up and grow...cart before the horse, I'm afraid." English Roseum will take full sun, but planted in sand is a real challenge. It doesn't hold nutrients or moisture. Replant using a good soil mix. Rhododendron have shallow roots, so be carefull to get a nice large root ball, but remove the lower part and replace with good soil. Here is a link that might be useful: How to care for rhododendrons and azaleas.

Thanks Kate--I guess I've been very much on the fence about whether they'll tolerate the cold here, will just have to see I think. The flowers look so gorgeous I think I have to try anyway, so I was going to put in 4-5 and see. I'm essentially zone 6 in the backyard, so maybe I'll have success with them if you have. Do you winter protect? My neighbor did lose some HTs from year to year but he planted the bud union above ground and didn't winter protect. My Austins always seem significantly hardier and I was hoping these, although marketed as HTs, were more mixed lineage and would be hardier too. The beds are a bit elevated, which hurts cold-tolerance but helps keep things well-drained. But I can bury the bud unions and throw on some bark mulch or leaves in the fall, which may help. Okay, Peter is officially on the list, and I think I MUST have Liv and Yves Piaget--the flowers look too wonderful to pass up. Every weekend the ground stays workable I keep fixing up the beds to accommodate more roses...so now I have room for another order from Roses Unlimited!

Gunnera and darmera are really similar, and I've tried them both - I like plants with big dramatic foliage. I don't have a wetland, my yard is a small in-town lot (1/3 acre) but I dug out a small low spot in a shady border in hopes of providing the kind of area bog plants would tolerate. Maybe next time I've got energy to spare I'll re-dig it and line it with plastic - probably would have to remove about 2 feet of soil for that to work well, so to be honest I probably won't ever find the time. There are 2 awesome clumps of gunnera, about 6' tall, in the Jardin des Plantes in Paris. They're growing in standing water, which is how I got the idea for my little wallow. I thought I had a photo of them, but I can't seem to find it.

I could talk old roses for hours, but I'll stick to one example. The town of Havilah, Kern County, CA, was more ghost town than the original county seat the first time I visited in the 1950s. On a drive through the mountain community I could easily identify where old homes had been by the roses wrapped around woodpeckered fence posts or climbing up crumbling chimneys. The mining petered out in the 1870s. People left, old log homes collapsed, the roses stayed, surviving snow and droughts. Perhaps my experience with old style roses is why I want to encourage these viburnums to thrive in spite of years of inappropriate care. I'm not in California any more, so I have to learn to care for what will grow here.