Answer: In general terms, there are always rodents wherever there are people. Fencing the garden would possibly help keep from attracting any new critters to the area, and using an enclosed compost bin would do the same. Good garden maintenance and sanitation should keep it from becoming a magnet for scavengers: Keep weeds and plant debris cleaned up to eliminate hiding areas, and pick all ripe produce immediately. Remember too that many rodents are nocturnal and would not be apparent during the day.
Many schools have successful gardens, so the problem is certainly manageable, and hopefully won't get in the way of your new venture. The benefits of gardening for schools and communities is well documented.
For specific information about rodent and other possible problem animal populations you might contact your county extension office for suggestions, as well as naturalists at local or regional parks. They should be able to help you assess the impact of your project on the local animal population and make control suggestions should any seem necessary.
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