Prepare jars and canner: Wash jars, lids, and bands. Keep jars hot. Set a rack in a water bath canner and add enough water to cover jars by 1–2 inches.
Wash peaches: Rinse peaches well. Use firm-ripe yellow peaches and discard any bruised, moldy, or overly soft fruit.
Blanch and peel: Cut a small X on the bottom of each peach. Boil for 30–60 seconds, then transfer to ice water. Peel once cool enough to handle.
Pit and slice: Cut peaches in half, remove pits, and slice or leave as halves. Keep cut peaches in lemon water or ascorbic acid solution to reduce browning.
Make syrup: Heat 4 cups water with 2 cups sugar until dissolved. Keep syrup hot. You can also use hot apple juice, white grape juice, honey syrup, or water.
Hot pack peaches: For best texture, add sliced peaches to hot syrup and bring just to a gentle boil. Heat through, but don’t overcook.
Fill jars: Pack hot peaches into hot jars. Cover with hot syrup, leaving 1/2 inch headspace. Remove air bubbles, wipe rims, add lids, and tighten bands fingertip-tight.
Process jars: Place jars in boiling-water canner, covered by 1–2 inches of water. Process at 0–1,000 ft: hot pack pints 20 minutes, hot pack quarts 25 minutes.
Cool and check seals: Let jars rest in the canner for 5 minutes, then remove and cool undisturbed for 12–24 hours. Check seals before storing.
