How to can strawberry jam

Spring signals the arrival of strawberry season here in North Carolina and one of my family’s favorite treats is strawberry jam. We live five minutes from a large family farm that grows and sells strawberries locally. I paid $36 for three large buckets of strawberries that weighed out to about 18 pounds of fruit. While you might be able to buy strawberries on sale at a better price, chances are they aren’t freshly picked that same morning. Nothing beats the flavor of fruit picked ripe from the field, the morning it is canned.

Canning jam doesn’t take special equipment. Any heavy stock pot can be used for water bath canning. It helps to have a funnel with a wide spout specifically for pouring the jam into canning jars. It also helps to have a jar lifter, but heavy grilling tongs will also work. Otherwise, all you need is fruit, sugar and canning jars.

Strawberry jam can be made with or without added fruit pectin. I prefer to make it without added pectin, but it takes longer to cook down and bring to the gelling point. If I’m in a hurry I will use a pack of Sure-jell to speed things along. I’ll include both recipes here along with tips based on my personal experience.

Strawberry jam without added pectin

  1. ripe-7557290Fill the sink with hot soapy water. Place 8 half pint or 4 pint canning jars and screw bands and soak until needed. The jars need to be hot before the fruit is added or you risk breaking the jar.
  2. Place flat lids in boiling water and keep hot on a back burner.
  3. Pour enough water in stock pot or pressure canner (used as a water bath) to a depth of two inches above the tops of the jars. Bring to a boil before the fruit reaches the gelling point.
  4. Start with two quarts of fresh, ripe, unblemished strawberries. Wash them thoroughly and allow to drain.
  5. Carefully cut away the cap (leafy end) and core of each berry with a sharp paring knife. 
  6. Working with one layer of berries at a time, cut and crush the strawberries with a potato masher. If you don’t have a potato masher you can pulse chop the berries in a blender or food processor, but be careful not to puree them. Jam is supposed to have bits of fruit in it.
  7. You should have about five cups of crushed strawberries when finished. Pour the fruit into a six or eight quart pot. 
  8. Measure exactly six cups of sugar and set aside in a separate bowl.
  9. Bring the crushed fruit to a rolling boil and add the sugar all at once. Add 1/2 teaspoon butter to help reduce foam.
  10. Stir until the sugar is dissolved and bring the mixture to a boil.
  11. Turn down the burner and simmer until the gelling point is reached.* You will need to tend the jam constantly, stirring occasionally to prevent burning.
  12. Rinse a few jars at a time in hot water and fill each with hot jam up to 1/4 inch from the top of the jar.
  13. Clean rim of canning jar with a wet paper towel. If you prefer use a spoon to scrape the pink foam from the top of the jam. This is harmless sugary froth, but the jam looks better without it, especially if given as a gift.
  14. Secure flat lid and tighten a band around each jar.
  15. Place jars immediate into the boiling water and process for 10 minutes. Make sure the water covers the jars by at least two inches.
  16. Remove from water and allow to cool at room temperature for 24 hours.

*clean-9808955Knowing when the fruit has reached the gelling point can be tricky. If you stop simmering the fruit too early you will have syrup instead of jam, too late and you wind up with soft strawberry candy. Both can be used. Syrup or jam that is too soft goes great on pancakes or ice cream. Strawberry candy is yummy dipped in chocolate or rolled in confectioner’s sugar. However, if you want jam, then knowing how to recognize when you should stop cooking the fruit is essential.

The gelling point is reached when the strawberries and sugar reach 220°F (104°C) and the mixture begins to thicken. Using a candy thermometer isn’t always accurate. I usually test the jam by taking a small plate that has been in the freezer and placing a drop of jam on it. If the fruit thickens immediately it is ready to ladle it into the jars and process.

Strawberry jam with added pectin

If you aren’t feeling comfortable with figuring out when the jam has reached the gelling point or you want to save a little bit of time, use added fruit pectin. I use Sure-jell and have very good results. In my experience, jam with added pectin foams a little more. 

Steps one through seven are the same as above. You will need exactly five cups of crushed strawberries.

  1. Measure exactly seven cups of sugar into a large bowl. Set aside.
  2. Stir in the package of Sure-jell powdered pectin into the crushed strawberries and mix well. Bring to a rolling boil. You may add 1/2 teaspoon of butter to help reduce foaming if you like.
  3. After the fruit and pectin have reached a rolling boil, add the sugar all at one time. Stir until the sugar is dissolved. Bring back to a rolling boil.
  4. Allow the jam to boil exactly one minute, then remove from the burner.
  5. Ladle the hot jam into hot jars, filling 1/4 inch from the top.
  6. Wipe the rim of the jar with a wet paper towel and secure the flat lid with the screw band.
  7. Place the jam-filled jars into the boiling water and process for 10 minutes.
  8. Remove from boiling water and allow to sit at room temperature for 24 hours.

Once you’re comfortable with the process the steps become automatic. It takes less time to set up. The instructions to wash the jars in hot soapy water before filling with hot jam serves a dual purpose. The hot soapy water not only cleans the jars, but helps prevent them from breaking when filled with boiling liquid. Likewise, the lids placed in boiling water are not only sterilized, but the the wax that will hold the seal on the lids is softened. Don’t skip these important steps.