Updated October 2026

How to Make and Can Jam, Jelly and Marmalade

Cook to 220°F (adjusted for elevation), fill hot jars with 1/4 inch headspace, and process 5 minutes in a boiling water canner.

Cook fruit, sugar and pectin to the jellying point, ladle the jam into hot sterilized jars leaving 1/4 inch of headspace, add two-piece lids and process in a boiling water canner for 5 minutes at up to 1,000 feet, 10 minutes up to 6,000 feet, and 15 minutes above that. Use jars that were only washed, not sterilized, and the time becomes 10 minutes at low elevation. That processing step is what makes a jar safe to store at room temperature.

Jam batch calculator

Pectin, acid and sugar

All fruit has some pectin. Apples, crab apples, gooseberries and some plums and grapes have enough to gel on their own; strawberries, cherries and blueberries do not, so they need commercial pectin or a high-pectin partner such as apple. For jelly without added pectin, USDA suggests using about one-quarter underripe fruit. Acid helps the gel form: too little and it never sets, too much and it weeps.

Do not cut the sugar in a traditional recipe. Sugar is a preservative as well as a sweetener, and too little lets yeast and mold grow. For lower-sugar jam, use a "less or no sugar needed" pectin such as the ones from Ball or Sure-Jell, and follow the recipe and processing time in the package, which is longer than for regular jam.

Testing for the jellying point

A candy or jelly thermometer is the most reliable test. Jam is done at 8°F above the boiling point of water: 220°F at sea level, 218°F at 1,000 feet, 216°F at 2,000 feet, and 2°F less for every further 1,000 feet. In Denver that is about 209°F. Check the thermometer in boiling water first.

No thermometer? Use the sheet test (two drops run together and slide off a cool metal spoon in a sheet) or the freezer test (a spoonful on a cold plate gels within a few minutes). Take the pot off the heat while you test.

Canning step by step

1. Sterilize jars by boiling them 10 minutes, adding 1 minute for each 1,000 feet above sea level. Keep them hot.
2. Make one batch at a time. Doubling a jam recipe often gives a soft set.
3. Fill hot jam into hot jars, leaving 1/4 inch headspace. Wipe rims with a damp paper towel.
4. Center new flat lids and screw on the bands fingertip tight.
5. Process in a boiling water canner, with water 1 inch over the jars, for the time below.
6. Cool on a towel for 12 to 24 hours, then check that each lid is concave and does not flex.

Paraffin wax seals are no longer recommended, and inverting jars is not a substitute for processing.

Freezer jam and refrigerator spreads

Uncooked freezer jam made with pectin needs no canner. Let it stand 24 hours at room temperature to set, then keep it up to 3 weeks in the refrigerator or up to a year in the freezer. Spreads set with gelatin and sweetened with sugar substitutes must be refrigerated and eaten within a month.

Marmalade

Meyer lemons, Seville oranges and grapefruit make good marmalade in winter. Peel the fruit with some white membrane attached, since that is where the pectin is, slice the peel thin and simmer it covered in water for about 30 minutes until tender. Add the fruit, boiling water and sugar, boil rapidly to 8°F above boiling (220°F at sea level), skim and process as for jam.

Picking your fruit

Strawberries peak in late spring, blackberries and peaches in midsummer, and Concord grapes in early fall across much of the country. In Florida and the Gulf South, strawberries come in late winter. Our strawberry growing guide has timing by region.

Troubleshooting

• Soft set: too little pectin or acid, a doubled batch, or undercooking. Remake small batches with added pectin following a remaking guide.
• Stiff or gummy: overcooked, or too much pectin.
• Crystals: undissolved sugar, or cooking too slowly.
• Mold: discard the jar. Mold on jam can produce mycotoxins, so scraping it off is not safe.

Store sealed jars between 50 and 70°F in a dark place and use within a year. Refrigerate after opening.

Sources we checked (October 2026): USDA Complete Guide to Home Canning (2015) and So Easy to Preserve (University of Georgia, 6th ed.) through the National Center for Home Food Preservation: General Information on Canning Jams, Jellies and Marmalades, Berry Jams without Pectin, Berry Jam (Uncooked), Citrus Marmalade, Testing Jelly without Added Pectin, Sterilization of Empty Jars, Storing Home Canned Foods.

Common questions