Vegetables can be grown in all sorts of tubs, broken buckets, even in empty Package boxes. The only requirement is, they should have a drain so that water is not stagnated. Of course depending on the type of vegetable you should see its light and shade requirements.
An inspirational Malayalam movie was released in 2014, How Old are you? which promotes the cultivation of vegetables on terrace in the urban areas, where there is no choice of free-land cultivation. The movie gave a strong message which urges the need of pesticide-free crops and vegetables to be cultivated in our own available spaces, instead of importing from other states. The movie marked the comeback of Malayalam's top actress of 1990s Manju Warrier after 15 years and her presence made a huge impact on Kerala's social life, and the message of the movie was well-conveyed.
You may not believe, the impact of the movie was so huge that during next Onam season, import of vegetables from Tamil Nadu received a huge blow and witnessed huge losses. People became more health conscious and many unwanted lands were converted to vegetable-production. During Onam season, most vegetables supplied here belonged to our own lands. The procedure is still continued, a welcome move from educated Keralites