Potted vegetables don't like to have "wet feet," or roots. Make sure your containers have at least one drainage hole to allow excess water to drain away. To aid drainage for containers bigger than about 16 inches in diameter, fill the bottom third of the pot with a materials that will create empty spaces, such as broken shards of terra cotta pots, large stones, or Styrofoam peanuts. The peanuts have the benefit of being lightweight, allowing you to move larger containers from one place to another.
(Globe Staff / Bill Greene)
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