· Brent Wilson's Answer
· Hi Leah - Good question. Because you want a perennial plant that will flower throughout the season for use as a border it makes answering your question a little easier for me:-) There just aren't that many perennials, much less shrubs, that will flower throughout the season. The trailing lantana was one choice but, you're right, some dogs can have a serious reaction to it if they eat too many of the leaves.
Here are some other choices:
Dwarf Butterfly Bush - These are relatively new introductions in the market. The only one I have a couple years experience with is Lo And Behold 'Blue Chip'. I love this plant. It flowers all season, handles blazing sun, and is fairly drought tolerant. I shear off spent flowers once or twice during the season. I've planted about 10 more newer varieties this spring to test them (all the Buzz series and Flutterby Petite series).
Drift Roses - These are also relatively new introductions as well. I love these dwarf roses! Last year, I planted every variety, except for 'Icy' (white) in my landscape. They all performed exceptionally well and flowered heavy in spring and on and off throughout the season. Drift Pink is an eyecatcher. On a couple varieties I have seen a little powdery mildew on the leaves early in the season. I just spray them with Neem oil if I see it pop up.
Homestead Verbena - This one is a trailing plant that flowers heavy in spring and then on and off through the season. It might need a good shearing in mid-summer to encourage blooms until frost. It grows to over 6 feet wide so you might not have the room.
Ice Plant (Delosperma cooperi) - A trailing, ground-hugginng, succulent that grow to about 2 feet wide. The Purple Ice Plant is the only one I know of that blooms from spring until frost.
Hope these suggestions helped,