And furthermore... I bought a couple of Cosmos last spring at HD. They were about 4 inches tall, and already in bloom. They never got any taller. They should have grown to 3 feet or more.

Recent arrivals from Colliefornia will buy their first warm-weather plants in March. When those plants die, they will buy again in April, and again in May. A retailer's job is not to wonder why, but to sell plants. Supply and demand. Did you see any tomato plants?

Yes: petunias being hung out in the open for sale now was a mistake.

Oregon gardeners have the itch, too.

And new gardeners buy what's available, never understanding why the plants fail.

Fred Meyer, HD etc. aren't nurseries. They're big box stores with plant departments. The plants are just some more stuff they think they can make some money off of - along with nails, underwear, cabinets, lumber ad infinitum. Support independent nurseries if you want something more than an indifferent approach to plants.

Yes, it is too early to plant petunias. The ones you saw likely just came from a greenhouse.