Making strawberry jam from fresh-picked fruit is one of the most satisfying things you can do with a big haul. Three ingredients, about two hours of active work, and you'll have jars of jam that last a year and taste completely different from anything at the grocery store.
This guide is written for beginners — no prior canning experience needed.
What you'll need
Equipment:
- Large heavy-bottomed pot (at least 6 quarts)
- Water bath canner or large deep pot with a rack — a Ball canning starter kit (Amazon.ca) / Amazon.com includes the canner, rack, jar lifter, and funnel
- Ball mason jars (Amazon.ca) / Amazon.com — half-pint / 250ml jars work best for jam
- Ladle
- Kitchen thermometer
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Ingredients (makes about 6–8 half-pint jars):
- 8 cups crushed strawberries (about 10–12 lbs whole berries)
- 6 cups granulated sugar
- 1 package (1.75 oz / 49g) pectin (regular or low-sugar)
- 2 tablespoons lemon juice
Understanding pectin
Pectin is the natural starch that makes jam set. Strawberries are low in natural pectin, so you need to add it — otherwise your jam will be runny.
Commercial pectin comes in two forms:
- Powdered pectin (most common) — whisked into the fruit before cooking
- Liquid pectin — added after the jam comes to a boil
Either works. The instructions on the pectin box are specific to that product — follow them over any general recipe. Different brands have slightly different ratios.
Step-by-step instructions
1. Sterilize your jars
Place clean jars in your water bath canner, fill with water to cover, and bring to a boil. Boil for 10 minutes. Keep jars in hot water until ready to fill. Place lids in a small pot of hot (not boiling) water.
2. Prepare the strawberries
Hull the strawberries. Crush them one layer at a time using a potato masher — you want chunks, not a smooth puree. Measure out 8 cups of crushed fruit.
3. Cook the jam
In a large pot, combine crushed strawberries and pectin. Bring to a full rolling boil (a boil that doesn't stop when stirred) over high heat, stirring constantly.
Add all the sugar at once. Return to a full rolling boil. Boil hard for exactly 1 minute, stirring constantly. Remove from heat.
Skim off any foam with a metal spoon.
4. Test for set
The wrinkle test: place a small plate in the freezer before you start cooking. Drop a teaspoon of jam onto the cold plate, wait 30 seconds, then push it with your finger. If it wrinkles and holds its shape, it's set. If it runs, cook for another minute and test again.
5. Fill the jars
Remove jars from hot water. Using a canning funnel, ladle jam into jars leaving ¼ inch headspace at the top. Wipe the rims clean with a damp cloth. Place lids on jars and screw on bands until finger-tight (not too tight).
6. Process in water bath
Lower jars into the boiling water bath. Water should cover jars by at least 1 inch. Bring back to a full boil and process for 10 minutes (adjust for altitude if needed — add 1 minute per 1,000 feet above sea level).
7. Cool and check seals
Remove jars and set on a towel, spaced apart. Don't move them for 12–24 hours. As they cool, you'll hear the satisfying "ping" of the lids sealing.
After 24 hours, check the seal: press the center of each lid. If it doesn't flex up and down, it's sealed. Any unsealed jars should go in the fridge and be used within a month.
Shelf life
Properly sealed jam keeps in a cool, dark place for up to 12 months. Refrigerate after opening and use within a month.
Troubleshooting
Jam is too runny: It may still set as it cools — wait 24–48 hours before worrying. If still runny, you can reprocess: open jars, pour jam back into pot, add another half-package of pectin, bring to a boil, and re-jar.
Jam is too firm/gummy: Too much pectin or overcooked. This batch is still fine to eat — use it as a spread or stir it into yogurt. Adjust pectin amount next time.
Jar didn't seal: Put it in the fridge and use within a month. The jam is fine, just not shelf-stable.
Foam on top: Normal. Skim it off before jarring. A small amount of butter (½ teaspoon) added to the pot helps reduce foam.
Other fruits that make great jam
Once you know the process, the technique works for nearly any fruit:
| Fruit | Notes |
|---|---|
| Blueberry | Naturally higher in pectin, may need less added |
| Peach | Peel first; pairs well with ginger or vanilla |
| Raspberry | High-pectin fruit; makes a beautifully firm jam |
| Blackberry | Strain some seeds if preferred |
| Cherry | Pit first; traditionally made without added pectin |
Frequently asked questions
Do I need a special canner? You need a large, deep pot with a rack to keep jars off the bottom. A dedicated water bath canner is inexpensive and convenient, but any large pot that fits your jars works.
Can I reduce the sugar? Yes, but use a pectin designed for low-sugar recipes (like Ball's low-sugar pectin). Standard pectin requires the sugar to gel properly — you can't just cut it in half.
How many strawberries do I need? About 10–12 lbs of whole strawberries yields 8 cups crushed, which makes 6–8 half-pint jars.
Is homemade jam safe? Yes, when following proper water bath canning procedures. The combination of sugar, acidity, and heat treatment prevents bacterial growth. Don't skip the water bath processing step.
Where can I find strawberries to pick? Browse u-pick strawberry farms near you — farm-fresh strawberries are at peak ripeness and make noticeably better jam than store-bought.