can I buy a simple shallow plastic or wood rectangular cart, maybe they come 5 inchs high and 5 feet wide by say 3 feet long, dump potting soil into it and grow herbs? tomatoes?
Sounds a little shallow for tomatoes. You can grow them in there, but do not expect great production. Herb on the other hand should do well in a shallow environment. (Rosemary may require deeper soil). I would say that most Italian herbs need good drainage
, especially rosemary. By Italian, I mean sage, oregano, thyme and Rosemary. I give those the best drainage. A raised cart/bed will benefit those the most. Thouh, my Italian parsley does not seems to be bothered by poor drainage.
Keep in mind that a raised soil system will require water more frequently.
Good Luck. By the way, what did you order?