Vegetable Gardening: Container Media
Container gardening is a great way to grow vegetables. You just need to make sure the media you put together will provide a good foundation for your edible plants.
An aerated, well-drained, lightweight soil is best for your container garden. Don't use soil from your garden, because it won't contain enough organic matter and can harbor harmful nematodes.
Soilless potting mixes are a good choice for your container gardens. You can also mix your own media, using a combination of different materials such as peat moss, composted bark, compost, perlite, or sand. The trick is to combine materials that absorb and retain moisture (such as peat moss) with materials that allow water to drain (such as perlite) into a loose, porous medium.
Don't make your potting mixture too light—you don't want top-heavy plants to topple over, or for your plants to be blown over by a strong wind. Avoid fine-textured or heavy potting soils since they usually hold too much water, reducing root aeration and potentially stressing plants.
Make sure containers have drainage holes to allow excess water to escape. Container media dries out faster than soil in beds, so check your plants every day or two to see if they need watering. Young plants can probably go a couple of day between waterings, while larger vegetables and herbs may need moisture as much as once or twice a day. Each time you water, soak your plants until moisture seeps from the containers. Water again once the soil feels dry to the top knuckle of a finger inserted into it.
Remember that the smaller the container, the more frequently it'll need to be watered. On the other hand, deep or large containers require exceptionally large amounts of potting soil. You can reduce the amount of potting soil needed by placing light-weight filler such as packing peanuts, lava rock, or empty plastic bottles in the bottom of a large container. These materials will not affect root growth of most plants but will make the container lighter in weight and easier to move.
It's best to replace the media in your containers at least once a year, and to re-pot plants when they need more room.