Looking for sun or shade perennials I don't have.

I planted 3 bareroot whips under a pin oak in late 2016. I mulched the planting area with composted stump grindings from a tree removal at the time of planting, and followed up with shredded leaves and wood chips in 2017 and 2018. They've been doing fine without any supplemental watering. They are near the bottom of a small slope in soil that drains very slowly. Standing water even forms at the bottom of the slope after prolonged rain, but hasnt hurt. 2017 was droughty but they were fine. Seems to suggest that with a soil high in organic material, mulch, and shade, they can handle dry periods. A neighboring nursery has some larger specimens in near full sun with a southeast exposure that look good too, but I dont know if they are watering them regularly.

I have one of each--regular size and dwarf. The dwarf is 20 yrs old and about 5/6 ft tall and 8 ft wide. The regular bottle brush is about 10 ft tall and wide it is also 20 yrs old. The dwarf doesn't bloom as well.

Thanks for the lovely photos, bengz6 and tsuga! Quick question, how much water do these typically need? I tend to over-water rather than under, so I don’t want to kill them with kindness. Been trying to keep the soil evenly moist, but not sopping wet, and some of the leaves are yellowing. But it seems like it’s the old sun-burned growth, not the new lighter green growth. Using a moisture meter and my index finger as a gauge.