I have a 3 to 4 foot tall rosemary plant hedge I have growing in my median strip between the sidewalk and the street curb. They have grown quite well and bloom several times a year. I have always watered them in the hot dry summer but I wonder if it is necessary or do they like a dry environment. They do seem to grow quickly for rosemary variety. I am not sure of the species but they were in the bargain shelf at our local big box store. I notice that now as they have become larger they tend to keep other weeds and grass from around their base.

It sounds like you have doing everything right! I'd continue that path. Other than maybe keeping it pruned. In some climates Rosemary can be difficult but your success proves otherwise. I would keep watering in that zone in summer as that can be tough conditions for any plant. Would love to see a photo... &

I water my plant every week or two during our annual summer drought, when we get no rain at all. It's probably a bad idea to let your rosemary go the whole summer without water.