British Columbia: Crop Rotation

I'm looking for some advice in managing my garden at work. The garden itself is fairly small, and we generally plant a row or two of garlic, cabbage, beets, turnips, and the remainder potatoes (currently 7 rows). We started over last fall and planted new garlic from two different sources and are now realizing that some of them brought along bulb mites. This is my first year managing the garden, but my understanding is that crop rotation has not been practiced correctly in the past. My question is how should I rotate these crops to ensure everything stays healthy, and is there anything I can do to kill mites/eggs that may be present in the soil?

Thanks in advance!