@roseseek thank you! that makes a lot of sense

@Grace Carroll Zone 10a you're welcome.

I live in a cold zone, but at the western-most edge of the Midwestern US and I consider my spots that get midday dappled shade the best rose real estate in my garden. They get plenty of sun without suffering as much from the intense, drying effect of the sun and winds we have during the hottest part of the day.

Totally agree with roseseek and M Magpie...

I used to live in Southern Arizona and I agree with what others have said here...my experience matches their recommendations. For example, I grew beautiful plants (not roses...this was before I fell in love with roses) on my porch which was completely shaded midday.

I've read blogs from Arizona rose gardeners who grow roses quite well under the shade desert trees like Palo Verde and Mesquite. Even desert native plants (think Saguaro cactus) grow under these trees when they are young. The nurse plants help protect the young plants from the harsh elements and get established.

I am in Arizona and know what the sun can do to many plants, including roses. While I'm not in the hotter regions of Arizona, (I'm higher elevation, 4,350) I still notice that during the hottest times of the year, everything and everyone benefits from a bit of sun protection. Because of that, I'm considering planting some roses near/ under a lovely spreading Mesquite tree in my backyard. However, I'm concerned about the roots of the trees greedily taking all the nutrients and water from my roses. Anyone on this forum in Arizona who can share personal experience on this? I understand that Mesquite trees are legumes and put nitrogen into the soil, so that part might be good.
Excuse me for hijacking this thread a bit....

Mesquite trees are a little different than many other trees because of their roots. They go down far deeper than many other species because of water needs. Up to 40 feet, in fact! Most trees like to keep their roots in the top 3ish feet of soil. So anyway, while many trees can pose annoying root competition problems (story of my life in my garden), I wouldn't worry about the Mesquite as much, as it knows to burrow roots down for reliable water. Yes your roses might share some water with the tree, but unless you're planting way too close to the trunk, you should be okay.

It's not just the leaves and young canes that suffer.

Most of my roses are on a south facing hillside. Spring growth doesn't begin until March and sometimes it takes 'til April for the right conditions. Then, some Mays, we get temps in the 90s for the first two weeks.

I have had horrible sun scald damage on the sides of new canes that face south. It's so wierd, the next spring when I'm pruning, the canes look positively excellent from the north side of the bed. And I do my thing happily. Then I move to the south side of the bed, look to the north and see canes with horrible grey damage. Gray NOT from the age of the canes but from the death of the south facing part of the canes. The north sides do continue to make blooms, the south don't.

Especially with HTs where the leaves aren't very dense, the damage is wherever the sunlight could hit canes .

This might not be a problem where winter kills all canes back to the soil line.

The sun scald damage is actually two-fold. First, once the bark and cambium are cooked in that spot, the tissue above that burn will die because the sap flow stops due to the cooked area. Second: Pacific Flat Head Apple Borers. Nasty things. They lay their eggs at a sun scald spot. They hatch and burrow into the dead area, eating the cambium. They girdle the canes and burrow downward toward the crown or bud union of the plant. Once they reach that, they kill the plant. The pesticide used to kill them once inside a plant is Lindane, a systemic which is concentrated in the wood instead of the fruit, and which you can no longer buy without a license. It used to cost $9 a pint at KMart garden center and was available everywhere you could buy garden supplies. I'm sure you are familiar with the "Caution-Warning-Danger" labeling. Lindane was labeled "Danger, Causes BLINDNESS". Your best defense against them is to maintain a good foliage canopy to protect the canes. In addition, anything you can do to protect them from the scalding direct sun will also assist. Remember seeing citrus and other fruit trees with their trunks painted white? That was an effort to prevent scald and borers. It's "fun" finding a blackened, split section of bark and digging into it and finding the "cocoa powder" colored and textured frass. You can continue mining the damage until you encounter the triangularly headed, puss colored borer. Don't feel safe having found the one as they are like other insects...where there is one, there are MANY. https://extension.usu.edu/pests/ipm/ornamental-pest-guide/arthopods/wood-borers/flatheaded-appletree-borer-pacific

Roseseek,

That makes me thankful for the double barriers of the western mountains and the Great Plains.

Although I don't understand why Glaciated Europe has so many more wild species roses than North America.

All my roses fry at some point every summer, doesn’t matter if DA, HT, FB or climbers. The canes don’t get too much damage but the young new growth and blooms are decimated. I cut them back a bit after the boiling point passes and they recover like nothing happened. My best performers with shade are Moonstone, Princess Elise and Olivia Rose Austin. They grow and continually bloom with only 2-4 hours of sun, although Moonstone is susceptible to powdery mildew, but that can be taken care of easily if caught early. Otherwise you have to cut her back to 12 -18 inches, defoliate and spray until the new growth comes in. Then she’s back to normal. But she’s a powerhouse and consistently pumps out blooms. Last year I put Don Juan and Abraham Darby in part shade so I’ll have to see how they perform this year.