Sorry, probably too late now, unless you put in some mums (or asters) for the fall. I can’t recall the name but there’s a beautiful fall variety of black-eyed Susans that are an annual in my zone (7a, Mid-Atlantic). They’re smaller but will do the trick. They will be in the stores in August or September.

Look around at your local nurseries or box stores to see what they’re showing and you like, always checking the tag and internet (maybe the store keeper; box store workers don’t always know) to see if they’re deer resistant.

See what you like that your neighbors have. If you can’t talk with them, take close up photos and use the plant identifier on your phone. Try to be sure about the variety; for instance a zinnia can be very short or very tall. That’s so with many general varieties, so take the time to check. Also, their habit: do they grow upright or spill over the sides of the container? If they come over the sides, will they intefere with mowing the grass, etc.? Since your container isn’t very high, you might lose the beauty (along with some) of the flowers that have cascaded to the ground.

Call the office of your local Master Gardeners; tell them your specific circumstances so they can give you the best advice. They won’t be allowed to recommend specific stores, probably not even specific brands, but could explain the different varieties for instance of petunias and even speak to whether that would need to be deadheaded.

For next spring, try annuals of lantana, shorter varieties of zinnia, petunias. Marigolds are profuse bloomers, but do and look better when cleaned. They will catch your eye from a long way away.

Try to ascertain how deep their roots go; a 9” pot is not deep. It also may not be deep enough to provide protection through the winter.

Also consider how tall the flower will be at maturity; anything too tall might not be supported in a relatively short pot. (Think how it will look; will the flowers be in a pleasing proportion to the pot?)

Observe the light in your intended area: will it have full (6+ hours of) sun? Not shaded by other things like a tree or bush or wall?

Finally, be careful about overfilling the pot with many plants; check the width expected at maturity. A 19” wide pot could be filled with just one plant; choose something that will last from spring to fall, and will knock your socks off and make you smile (without ever getting tired of it) every time you see it.

"Finally, be careful about overfilling the pot with many plants; check the width expected at maturity. A 19” wide pot could be filled with just one plant; choose something that will last from spring to fall, and will knock your socks off and make you smile (without ever getting tired of it) every time you see it."

Ditto on both points.

Deer will not touch marigolds, Madagascar Periwinkle or Russian Sage, Russian Sage is a perennal in the ground (not sure about in a pot for you). Most herbs are also good (lavender, rosemary, sage, etc.). Good luck with deer in the yard.

Angelonia. It answers all your requirements and then some.

I love angelonia!

This is one lantana plant in our brick mailbox, planted in June.

The one above has purplish flowers, there are many about to open when the photo was taken.