Answer: Generally, the soil will need some enrichment and renewal each spring. You will probably find that the soil in small containers is quite depleted and that the texture is deteriorated by the end of the season as well. Larger containers may only need to have part of their soil replaced, depending on which plants you grow in them. To reduce leaching over the winter, you could store them under cover such as a tarp, but there is no harm in letting the soil freeze -- in fact, it may help cut down on insect pests if it does freeze. However, if you have used terra cotta pots you should be aware that they will crack or possibly shatter if allowed to freeze while moist or full of moist soil so you will need to protect those away from freezing temperatures.
Since you are new to container gardening, you might wish to read up on it a bit because there are some special techniques that can be very helpful. One book I really like is "Container Gardening for Dummies" by Bill Marken, ISBN 0-7645-5057-8 -- it includes tips about everything from soil mixtures to suggested plant varieties. Enjoy your containers!
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