You absolutely need to do four things to have happy, productive containers. 1. Fresh potting soil every year. Never use soil from your garden, it is not airy enough and it may harbor viruses. 2. Adequate water, never let the pot dry out completely. Who wants to take a vacation during the growing season? 3. A deep enough pot. Check on the seed packet but you hardly ever want a pot depth less than 18 inches. 4. Finally, super drainage. Get your pot off the ground so the drainage hole can do its work. Use pot feet, bricks also work well. You will succeed!