Water Retentive Polymers
About the only drawback that comes from gardening in containers is their daily need for water, but these days even that hassle has been eliminated by a little invention called the water retentive polymer.
When the polymers are dry they look like old-fashioned ice cream salt, but when they are wet they become soft, full of water and gelatinous.
They are great for container gardens because as the plants need moisture they draw water from the granules, which act like a water storage system.
These polymers are easy to use and a little goes a long way. Another advantage is that you don't have to fertilize as often because you won't flush all of the nutrients out of the soil by watering everyday.
You can find water retentive polymers at your local garden center, sold either in individual packets or I like to buy potting soil that includes both water retentive polymers and slow release fertilizer. It's a great way to make container gardening even easier!