Can You Reboil Runny Jam if It Doesn’t Set? | What to Do

runny jam upside down jars

If you are a jelly maker, whether you are a novice and are just learning the ins and outs of jelly making or are a pro who has been making jelly for years, occasionally at least one batch of jam or jelly will not set properly. I have had this happen several times over the years and can give you some hints as to how this can be prevented and some suggestions for what you can do if it does happen.

To fix or “re-set” runny jam or jelly, pour the contents of each jar back into the pot. For 6-8, 8-ounce jars, add another 1/2 cup of sugar mixed with a half box of pectin (or 2 tablespoons of bulk pectin). Reboil for a couple of minutes more and prepare the jars as you would normally, fill and reseal.

Another idea is that if jam or jelly doesn’t set properly, you can just keep the product as is and use it as a syrup, sauce, or topping. Even so, the best way to deal with this issue is to make sure you follow a checklist when measuring and adding ingredients that should help ensure this problem doesn’t happen again.

Of course, sometimes the stuff simply does not firm up as it should. The rest of this article will give more details on the subject.

What to Do When You Have Jam or Jelly That Doesn’t Set

Did this ever happen to you? You had a gallon of your favorite fruit and decided to make it all into jelly. At the end of the day, after boiling the fruit, straining and measuring the juice, and making 3 batches of jelly, you discover that one batch just did not set. It is still the consistency of half-set jello. Sometimes you may realize that you made a mistake and added the wrong amount of one of the jam-making ingredients, but more often than not, there just isn’t anything you can put your finger on that caused the problem and kept the jelly from setting.

If your jam or jelly doesn’t set properly, more than likely it did set somewhat and is the consistency of half-set jello. Here are some options for what you can do with this jiggly jelly:

  • Just Spread It As Is
    This jelly is perfectly good and actually spreads better on a sandwich or a piece of toast than fully-set jelly. Once refrigerated, the consistency will be even more firm. You can use the jelly as it is and enjoy the easy spreading.
  • Use the Thin Jelly as a Sauce or Topping
    It would make a wonderful, fruity-tasting syrup for your pancakes, a fantastic topping for your ice cream or cheesecake, or just heat it to spread as a sauce on your pork roast.
  • Or, Retry Making It Set with the Process Below

Step-by-step process firmer jam or jelly:

  1. Prepare your chosen type of jars as you would for any jelly by washing in hot, soapy water and rinsing well. Make sure you use high-quality mason jars and avoid cheap the cheap ones. Here are the jars I recommend, they come with everything you need including lids and rings.
  2. Place jars in a pan of water, bring the water in the pan to the boiling point, and allow them to boil for the entire time the jelly is cooking. This will sterilize the jars.
  3. Bring another pan of water to a boil, then reduce heat to simmering and place lids in that water until needed.
  4. Open all the jars that did not gel.
  5. Pour the jelly back into your jelly-making pot (Click the link to see the one I recommend), or Dutch oven. I do not recommend using a pressure cooker.
  6. For 6-8, 8-ounce jars, add another one-half cup of sugar mixed with a half box of pectin (or 2 tablespoons of bulk pectin). Stir until pectin is dissolved.
  7. Bring to a boil, reduce to medium heat, and cook for 2-3 minutes more.
  8. Turn off the burner, skim any foam from the top of the jelly, and pour it into prepared jars.
  9. Wipe the jar rims with a clean damp cloth before affixing lids to make sure there is nothing on the rims to prevent a good seal.
  10. Affix the lids that have been in hot water for at least ten minutes.
  11. Move the jars of jelly to the prepared surface and leave untouched until completely cool.

Checklist to Follow When Making Jam and Jelly

  1. Use a Well-Tested Recipe
    Jelly making is not a hit-and-miss affair. A gel is formed when the right ratio of fruit juice, sugar, acid, and pectin is combined. If you start adjusting the amount of any of the ingredients, the jelly may or may not turn outright. Also, you cannot use the same recipe for all kinds of fruit. This is because all fruit contains some natural pectin, but not the same amount. For example, when making apple jelly which is high in natural pectin, the ratio of ingredients should be 5 cups of juice to 7 cups of sugar with one package of fruit pectin and no added lemon juice or any other type of acid. But, when making blueberry jelly which is very low in natural pectin, the ratio should be 3 & 1/2 cups of juice to 5 cups of sugar with one package of fruit pectin and 1 tablespoon of lemon juice. The recipes found on this site are tried and true and can be depended on to produce a good jelly when directions are carefully followed.
  2. Measure All Ingredients Exactly
    Use the same measuring cup for juice and sugar to ensure the proper ratio of ingredients. I recommend a measuring cup that measures all the way to the top because the hash marks on most measuring cups make it difficult to get the same exact measurement every time.
  3. Cook for the Designated Length of Time
    Using a timer is the best way to do this. I, for one, can’t be trusted to remember just what time the jelly came back to the second full rolling boil. In addition to the necessity for using the right ratio of ingredients to ensure the jelly sets properly, the jelly must come to a full rolling boil and remain at that temperature for a certain length of time.
  4. Proper Storage
    Make sure the pectin has been stored properly and is fresh when used. It is best when the package is kept closed and stored in a cool, dark storage area such as a cabinet or pantry. In case you’re wondering about what type of pectin I use, click here to see the Amazon listing.
  5. Use Dry Jars
    Make sure no water has gotten into the jars before pouring the jelly. If you add a little water, you no longer have jelly, just colored and sweetened liquid. Does it sound like I know what I’m talking about?  Yep, if it can be done, I’ve done it!
  6. Don’t Play Peekaboo
    When the jelly has been poured into the jars and lids affixed, place it in a prepared area where it can remain untouched until completely cool. In other words, leave it alone and don’t keep checking it. (This is the hardest part for me. I want to keep picking it up and looking at it.) Sometimes, it takes up to 48 hours for the set to be complete, so put it in an area where it won’t have to be moved for a couple of days.

What Causes Jam and Jelly to Set?

Jam and jelly reach the right consistency and become set under just the right conditions.  Those conditions include:

  • Ingredients
    Juice, sugar, acid, and pectin – There must be the right combination or ratio of these ingredients for a set to occur.  Fruit naturally contains acid and pectin, but the amounts differ in the different types of fruit, and the amounts vary by the ripeness of the fruit. This is the reason for the different jam and jelly recipes for different types of fruit. As I mentioned before, the recipe for mayhaw, apple, crabapple, and concord grape jelly is 5 cups of juice, 7 cups of sugar, and 1 box of fruit pectin because those fruits are high in natural pectin. But, the recipe for blueberry and blackberry jelly is 3.5 cups of juice, 5 cups of sugar, 1 tablespoon of lemon juice, and 1 box of fruit pectin because these berries are low in pectin and need the addition of lemon juice because of low acidity. Fruit contains the maximum amount of pectin when it has just reached the ripe stage, but as it continues to ripen more, the pectin amount decreases.
  • Heat
    The ingredients must reach a hard boil, or full rolling boil, for the jelly to set, and that temperature must be maintained for a certain length of time.
  • Time
    The hard-boiling point must be maintained for at least one minute for a set to occur.

How Long Does It Take Jam and Jelly to Set?

There is no set answer to the question of how long it takes jam and jelly to set.  There are just too many variables. Even the weather can affect the way jam and jelly sets.  If it is raining or the humidity is extremely high, it can take longer for the jam and jelly to become firm. Most sources say that it can take between 24 and 48 hours.

Jam or jelly takes about 3 or 4 hours to set under average conditions. If you have followed the recipe exactly and have left the jars of jam and jelly alone after having finished a batch, on a dry, sunny day, they should be set by the time they are completely cool.

Having made a lot of jelly and a good bit of jam in the past few years, I have fine-tuned my process for jelly so that most jars are completely set within 1.5 to 2 hours.

Pro Tip: My process includes adding extra pectin, 4 tablespoons of bulk pectin rather than the recommended 3 tablespoons, and cooking for 9 minutes rather than the standard recipe of cooking 1 minute and then processing in a boiling water bath for 5 minutes. I leave out the boiling water bath process completely for jelly. For jam, I cook for 3 minutes and use the boiling water bath for 10 minutes. Jam is easy to burn if you try to cook much longer than that.

Even though your jam and jelly may be firm after 3 or 4 hours or if you follow my recipe for jelly and your finished product is firm in 2 hours or less, I would still recommend that you let it sit for at least 24 hours before moving the jars just to ensure you are getting the best set possible.

Important: If it isn’t set as firmly as you would like after 24 hours, I would just let it sit, undisturbed, for another day. After 48 hours or so, if your jelly or jam still doesn’t have the desired consistency, then you can decide whether to try to “fix” it, or just use it as is.

If you do not have a boing water bath canner, here is the one that I recommend.

Are There Any Types of Jams or Jellies That Cannot Be Reboiled?

Any jelly can be reboiled to obtain a firmer consistency. However, jam is more difficult to reboil because it can scorch the fruit. If your jam is runnier than you would like, only reboil it for 1 minute, stirring continuously so that it doesn’t burn.

You may not want to try forming up jam at all. Because jam is full of fruit and naturally thicker than jelly, I don’t mind it being a softer set and usually don’t bother trying to fix or reboil it. This is because jam is full of fruit and naturally thicker than jelly.

There should not be a problem reboiling any types of jelly to obtain a better, firmer consistency. I made several batches of pepper jelly recently, one of which didn’t set as it should have. So, I reboiled that one batch, and it turned out just fine. It seemed to me that it may have been a little too firm, but the person I made it for liked it that way, so all was not lost.

Pro tip: If you are making jam using gelatin or jello as a thickener, boiling gelatin for too long will weaken its gelling ability, so if it doesn’t set properly, you cannot reboil it.

How to Fix Runny Freezer Jam

If your batch of freezer jam is runny and you would like to thicken it up a bit, use the process listed above to fix it. There are many different freezer jam recipes, so you may have to adjust the process a little.

For example, as mentioned above, if you are making a freezer jam recipe that uses gelatin or jello as a thickener, it cannot be reboiled, so it would be better used as is or just add a little more of your thickener. Most freezer jam recipes only make about 4 eight-ounce jars, so for that amount, you would only need to add 1 additional tablespoon of pectin.

Can I Use Tapioca as a Thickening Agent?

We all know that fruit pectin is the most widely used thickening agent used in jam and jelly, but I’m sure some of you have wondered, as have I, whether tapioca could be used instead of the pectin. Pectin is found in fruit, mainly apples, and tapioca is extracted from cassava tubers, so they are both natural carbohydrates. And, because tapioca has no common allergens, is easily digested and cholesterol-free, contains fiber, iron, manganese, calcium, and vitamin B, and is low in sodium, it should be a healthy product to use in your jam and jelly.

Tapioca can be used as a thickening agent. It is a natural substance that absorbs liquid and thickens and gels. It is a healthy and flavorless replacement for other types of thickeners.

Here is a good recipe to use when you try the tapioca as a thickener for Jam:

A Quick Recipe for Homemade Refrigerator Jam Using Tapioca as a Thickening Agent

  • 2 cups prepared Strawberries (washed, trimmed, and chopped)
  • 1/2 cup Honey
  • 1 teaspoon Lemon Juice
  • 1 package Fruit Pectin or 2 tablespoons Chia Seeds or 2 tablespoons Tapioca or 2 tablespoons Cornstarch
  1. Place strawberries, lemon juice, and tapioca in a Dutch oven or other pot (not aluminum), and bring to a boil.
  2. Add honey and return to a boil, boiling for 2 minutes, stirring frequently.
  3. Reduce heat, and cook over medium heat for 10 minutes, stirring frequently and skimming off foam. Use a potato masher to mash the fruit while it is cooking.
  4. Pour into prepared jars, wipe jar rims and affix lids, and set on a towel to cool.
  5. Once the jam has cooled completely, place in the refrigerator, ready to use.

Once the jam is made, it will keep for at least 6 months in the refrigerator or for a year in the freezer. Any alternative sweetener can be substituted for the honey, and the amount of sweetener can be adjusted to taste. Chia seeds or fruit pectin can be substituted for the tapioca to thicken the jam, or this recipe can be made without a thickener by cooking it an additional 10 minutes. Don’t use gelatin or jello to thicken the jam if you are going to store it in the freezer as the liquid would begin to separate when thawed.

Can I Use Cornstarch as a Thickening Agent?

Cornstarch can be used as a thickening agent. It is a natural thickener as it is a product of corn.

It is another thickener that could be used in jam.  This is a product that most of us have in our cabinets on a regular basis and could be used as a substitute for the pectin in the recipe listed above for homemade refrigerator jam. Use 2 tablespoons of cornstarch as a thickener in this recipe.

Jello and Gelatin can be used as a thickener as well, click here to read more.

Can I Reuse Lids from Unset Jelly?

If you have to recook jelly that does not gel, it will probably be alright to reuse your lids, but I do not recommend it. However, if you are making the jelly for your own use, go ahead and reuse the lids as you can always immediately refrigerate any jars that do not seal properly, and use those jars first.

Does Runny Jam or Jelly Last Just as Long?

The consistency of jam and jelly has nothing to do with its shelf life and will last just as long as if it were set perfectly. So, not to worry, if you decide to use that runny jam or jelly just as it is or save it to make a sauce or a topping, you can rest assured that it will last for at least 2 years in your pantry.


Making jam or jelly is a fun hobby that can last a lifetime and with experience comes perfection. If you would like to fine-tune your jelly-making process, I would recommend following all of these tips. Doing so will ensure that your jam or jelly has the best chance of setting firmer and faster, and more importantly, tasting delicious.

  1. Use a good recipe
  2. Measure exactly
  3. Cook for the specified time
  4. Use fresh pectin
  5. Make sure no water gets into the jars before pouring the jelly
  6. Give them 24-48 hours to cool and set

After it cools, if a batch of jam or jelly doesn’t set properly, there is no reason to stress over it. You can either use it as it is as an easy spreader or follow my simple directions for a quick fix and then enjoy the fruits of your labor. Enjoy the process and be sure to comment if you have ideas on how to make everything go smoother (or less smooth in this case).

For more, don’t miss How to Make Jelly, Jam, and Preserves: A Complete Beginner’s Guide.

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Anne James

Hi, I'm Anne but my grandchildren call me Jelly Grandma. I have over 50 years of experience as a Southern cook and am a retired librarian. I love sharing what I have learned. You can find me on YouTube as well! Just click the link at the bottom of your page. I hope your visit here has been a sweet one.

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