Rick .... I've searched for this kind of information for a while and it's good to know that others find it as difficult to find specific information, too.
The only genus of plants that I know well happens to be roses ... a woody plant. Knowing the botany of the plant has helped me select roses that do quite well in my hot summer temps. It's not the availability of water that creates heat stress, but how the plant moves moisture through the plant. A rose can be well watered, but if the transpiration rate is higher than the plant can pull moisture up to the top growth, the plant will experience heat stress and will start discarding growth it cannot support. Many roses go dormant in periods of high temps. Often a rose will abandon leaves it cannot support, because it is in survival mode. Over time, I've learned what plant characteristics a rose must have to thrive in my climate, but now I want to expand my plant pallet and had hoped others would know more about heat zones than I do.
Porkpal ... no the Sunset zones do not help. They, too are geared towards cold tolerance. I am in Sunset zone 7. My summer temps are generally in the 90s to low 100s and I believe the heat stress is a far greater issue for selecting plants than cold hardiness. Other than tropicals, it seems that there is a wide range of plants that can handle my cold temps during the winter.
Danita ....... Thanks for the link, I think it's easier to use than the book. California has all 24 Sunset zones and all 11 AHS cold hardiness zones.
I have no shade in my gardening area ... the area protected from deer ... and my full sun in Heat zone 8 is very different from full sun in Heat zone 4 or 5 like Rick has in Washington.
Since most nurseries don't supply heat zone information, I'll have to ask about specific cultivars on the various forum.
Thank you all for taking the time to reply.
Smiles,
Lyn
