@Carolyn22........
I have the same high heat but in an arid climate.
I am a rose nut that has been trained by rose breeders, so I tend to research plants for my climate differently than the average gardener, which drives my gardening friends absolutely crazy. I also tend to relate the breeding development of plants to the breeding developments in the history of roses, because that is what I know best. I want to expand my plant pallet and truly fell in love with heuchs and thought I needed to know more about them, so that I could select the right plants.
I think the current heuchs are very much a transitional class very much like the hybrid perpetuals were in roses. HPs were the first class of roses crossed with the tea roses from China. Over 5,000 new cultivars were developed, but few have passed the test of time simply because the were not good plants. Breeders continued to work with them and gradually developed stronger plants, many of which are still in commerce.
From what I have read, huechs have only been actively bred since the 1980s, which, to me, says they are in the early stages of development.
Since I was trained by rose breeders, one of the things I had to learn was about the species roses used in the breeding of roses. So, my initial research was about species huechs. Yeah ... I developed a spreadsheet ...
, but I haven't created the lineage trees for the non-species heuchs. (I haven't had time ...
)
As I have been learning, I often see that if
H. villosa is included in the lineage of a new heuch, it is said that is an indicator that the new plant will be "heat tolerant". However, that broad statement is not necessarily true because
H. villosa is native to the southeast of the US with a far more humid climate than mine. (Those plants should do well for you, if you go by lineage.)
I know there are several species which are found in arid climates, but haven't finished researching them to find if they have been used in the current breeding programs.
The research will help, but I need to learn about the basics about growing heuchs. There is a lot of contradictory information about culture and none of the information I've found addresses growing the plants in a more arid climate.
My most successful heuch is 'Amethyst Mist'. 'Silver Scrolls' is OK, but not thriving. 'Autumn Leaves' may not make it in my garden. It could be the plant or it could be that I don't know how to care for it properly.
I am gardening in glacier debris which has excellent drainage and the roses, which also require good drainage are doing well, so I don't think it's a drainage issue that is keeping the plants from thriving. My plants are located in a deer protected area as I found out the hard way that my deer don't read and will go after the heuchs as soon as they see them.
'Amythyst Mist', gets more sun than the other two plants, but .... that may or may not be a factor. I just don't know.
Sorry for the long post, it's the only way I know to get more information from the people who actually have grown the plants.
Smiles,
Lyn
