Garden Relish

8 bell peppers, red and green, ground or finely chopped in food processor
4 cups ground green tomatoes, or finely chopped in food processor
4 cups ground pickling cucumbers, or finely chopped in food processor
3 cups ground onions, or finely chopped in food processor
3 1/2 cups cider vinegar
2 cups sugar
2 tablespoons pickling salt
2 tablespoons mustard seeds
1 teaspoon celery seeds
2 tablespoons mixed pickling spices in a tied cheesecloth bag