Carrots need very deep long containers, and the dirt should be very clean, no pebbles or the carrot will deviate in shape. Thin well after the sprouts appear, I mean, make sure they are spaced well enough around. There is a hybrid variety that grows in little balls like a radish.
Strawberries grow best in a terracotta strawberry pot, the vines need something to settle on, anything tiered will do. I have stacked 3 different sized flowerpots each filled with dirt (obviously), smallest on top (again, obviously) and it looks awesome!! You can use an old kitchen plate on the bottom pot to handle and balance the weight of the upper two.
Baby's breath I always had trouble with, it blooms, then dies, and it's seeds quickly grow up and they too bloom again in the fall, not too pretty when it's not in bloom. I started growing Alecea ( I think) instead.
I'm not sure about gardenias, but my poppies love dry crappy soil and seem to do best there in the hot sun.
Broccoli is hardy with nice green succulent leaves, shouldn't have a problem, just make sure you have a proper nutrient balance, same with the spinach.