and thank you for the feedback.
Try changing the parameters you use to search. It helps to understand how the database is organized and how search results are returned.
"Full Sun" is treated separately from "Full Sun to Partial Shade" and many full sun plants are placed in the latter category because they tolerate/enjoy a wider range of exposure. Searching only for "full sun" will not show you the latter plants.
When you do zone searches you have to bear in mind that they only return plants whose limit is the zone specified. For example, searching for zone 6b does not return plants whose limit is 6a or 5b or anything lower than that. There are lots of hardy plants in the database below the 6b limit. I tried searching for xeriscape plants, full sun to partial shade, slightly alkaline soil, whose limit is 5a and there were 15 results. The same search for 6a returned 18 results.
https://garden.org/plants/sear...
Soil alkalinity is likely to be the limiting factor in the search, and I'm guessing that's because a lot of plants do not have specific soil pH preferences specified in the database. If you leave out this detail from the above search, you get 99 results (many/most of which do not have any soil pH listed). As I mentioned before, this list is incomplete for your zone because it does not include plants whose limits are lower than 6a.
https://garden.org/plants/sear...
The database is not complete in all fields for all plants, it is an evolving thing which is continually being improved over time. If you spend some time looking at individual entries (try searching your favorite plants) you will have a better understanding of where the gaps are. If you expect perfection in any plant database, you are guaranteed to be disappointed.
