Growing vegetables isn't so difficult as long as the conditions are right. I've been growing tropical vegetables like spinach and kang kong in these small planters measuring about 17x17cm. Vegetables thrive as long as they receive enough sunlight and water. It is important to choose a growing medium that provides good drainage.
The best thing about growing kang kong is they continue to grow after each harvest. I leave about 2 cm of stump and new leaves will grow very quickly within days.