Cook com in boiling water, 5 minutes. Remove cobs to ice water. Cut kernels from cob with knife; you should have about 5 cups kernels. Add onion, peppers and celery.
Stir vinegar, sugar, salt, mustard seed, celery seed, dry mustard and turmeric in a large non-aluminum Dutch oven to dissolve sugar and salt. Add vegetables. Simmer 15 minutes, stirring constantly.
Sterilize canning jars, lids, screw bauds according to manufacturer's directions.
Ladle hot relish through funnel into hot jars, leaving 1/2-inch headspace. Cover with lids; screw on bands. Process jars in large pot boiling water 15 minutes; jars should be covered by 1 inch of water. Remove jars to rack to cool. Test seals. Store in cool, dark place at least 2 weeks. Makes 3 pints. Enjoy!
Note: Always follow USDA guidelines for safe canning! https://nchfp.uga.edu/publications/publications_usda.html#gsc.tab=0