According Farmer’s Almanac Naniamo gets an average of 171 frost free days, and the frost free growing season starts on April 28th. Further south in Victoria the average frost free date is April 19th. Expect a first frost around the beginning of November.
Of course many vegetable and herb plants can tolerate frost. Here is listing of Frost Tolerance of Vegetables to help you get started.
It is always interesting to see how Vancouver Island compares to the rest of Canada for frost free dates and growing season length, here is a handy table put out by the Farmer’s Almanac for various Canadian cities.