Despite popular misconceptions, all types of pepper are considered a "low acid" food, and cannot be preserved with water-bath canning unless an acid, typically vinegar, is added to the peppers. However, the vinegar's pickling effect creates a flavor that many people enjoy. This method is also one of the best ways to retain most of the peppers' crunchy texture.   Note: Because this process can be complicated, reading all the instructions is recommended before you begin. A water-bath canner will make this easier. If you have a pressure canner, see tips for a way to preserve peppers without pickling first. Put sturdy, undamaged canning jars and lids through a hot dishwasher cycle, or place them in a pot of water and simmer, below boiling point, on the stovetop. This helps keep the jars clean, and prevents them from shattering when boiling water is poured into them. You'll need tongs to remove jars and lids from hot water. Peppers should be prepared for preservation by washing them, removing the stems and seeds, and cutting them to the size you wish. Using larger jars or non-canning jars may be unsafe for this recipe. Leave about 1/2–1 inch (1.25–2.5 cm) of head space at the top of each jar. About 1 lb (0.45 kg) of peppers is typically required for each 1 pint (475 mL) jar. Vinegar can be used as a preserving fluid for peppers, provided it's the correct type of vinegar. Try to use a high-quality vinegar with at least a 5% acetic acid content (or 50-grain strength).). Avoid using homemade vinegar unless you can be sure it meets this level of acidity. Clear liquors will preserve the original color of the pepper, while cider and wine vinegars can darken the peppers but will otherwise work just as well. A typical canning bath batch of nine pint jars (or nine 500 mL jars) requires at least 9 cups (or 2250 mL) solution. At least 1/3 of the solution should be vinegar to safely preserve the pickles, but the other ingredients are up to your taste preferences. Here are two suggestions:  For bell peppers, use 3 cups (700 mL) vinegar and 3 cups (700 mL) water, and 3 1/2 cups (815 mL) sugar. Add 4.5 tsp (22.5 mL) canning or pickling salt for flavor, unless you want to make a low-sodium version. Optionally, add 9 peeled cloves garlic for flavor. For hot peppers, or a mix of hot and sweet peppers, try 5 cups (1200 mL) vinegar, 1 cup (240 mL) water, and 2 tbsp (30 mL) sugar instead of a tarter result. Optionally, add 2 tbsp (30 mL) canning or pickling salt, and 2 cloves of garlic. Transfer the vinegar and water solution to a large pot over medium or high heat. Wait for the mixture to reach a rolling boil, then immediately remove from heat. Boiling helps eliminate germs and microbes that can contaminate the preserved peppers. If you accidentally leave the solution boiling for more than a couple minutes, you may wish to add a little more vinegar and bring to a boil a second time. Over-boiling can destroy some of the acetic acid in the vinegar, which is the main preservative. Pour your hot mixture of vinegar, sugar, and water into each pepper container until the peppers are fully covered by liquid. Try to still leave about 1/2 inch (1.25 cm) of space at the top of the jar or container. Run a knife around the rim of each jar to dislodge air bubbles. Use a damp, freshly cleaned cloth to wipe the inner rim of each jar for additional cleaning. Seal the canning jar according to the manufacturer's instructions, typically by placing the lid on top and screwing the rim over it and the jar. Fill a water-bath canner, or a large pot with a metal rack on the bottom, about half full of water. Heat this until it is almost boiling, then lower the sealed jars onto the rack. Move the jars so none of them are touching each other, or the sides of the container. The water must be deep enough to cover the jars with at least 1–2 inches (2.5–5 cm) of water. The jars must be boiled for a certain amount of time, to create a safe environment for preservation. Start timing the peppers once the water begins boiling, not when they are lowered into the water. If the boiling is interrupted, you must begin timing from the beginning.  If you are at a high altitude, start with the times below, then add an additional 2 minutes per 1,000 ft (300 m) above sea level.  Boil hot peppers for at least 15 minutes in jars up to 1 pint (500 mL). Boil sweet peppers or bell peppers for at last 10 minutes in jars up to 1 pint (500 mL). Safe boiling times for larger jars have not been established for these recipes. You may be able to find another pickled pepper recipe with a recommended boiling time for 1 quart (1 L) jars. Store your finished peppers in a cool, dark place, no warmer than 75ºF (24ºC). Under these conditions, the pickled peppers can typically last for one to two years. Once you open a jar, keep it in the refrigerator until the peppers are eaten. Do not eat pickled peppers from a jar with a rounded or bulging lid, or if the peppers have turned brown or black.
Follow this process to preserve peppers safely for up to two years. Wash and heat canning jars and lids. Wash and prepare the peppers. Fill clean canning jars 1 pint (500 mL) or smaller with peppers. Select a strong vinegar. Mix vinegar, water, and optional ingredients. Bring this mixture to a boil. Add the hot vinegar mixture until the peppers are submerged. Clean and seal the jars. Place the jars on a rack in a pot of hot water. Learn how long to boil the jars. Allow to cool.