Answer: Sound slike your garden is going great guns! The soil should be very rich, so you may not need to add any fertilizer this season. You could run some basic soil tests and see what the results show, or you can keep an eye on the plants and let their performance be your guide. Although unlikely given the mix you used, it is possible that rain will leach some of the nutrients.
As long as you are replacing the soil mix form year to year, you should be able to leave the bins in place since rotation is geared toward preventing soil based problems and managing fertility levels. (Make sure to use that great leftover compost on your ornamental plants!) However, do be sure to clean up and remove all plant debris in the fall to limit any chance of carryover of insect or disease from year to year.
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