Maple Syrup Lasts a Long Time Before Spoiling
I don’t know about your family, but in our house, an open bottle of maple syrup doesn’t last long—especially with waffles.
Even if you don’t consume your maple syrup as quickly as we do, it won’t go bad if you store it properly.
Many people first experience the great taste of maple syrup with breakfast. You can quickly get hooked on the great taste and the health benefits of maple syrup and purchase larger quantities for use in all kinds of maple syrup recipes.
You should use maple syrup when cooking. It’s perfect for replacing corn syrup and granulated sugar to make healthier recipes.
Breakfast syrup or pancake syrup is a totally different product. Be sure to check the label for ingredients when purchasing as it’s often burnt sugar water with maple flavor added, and it is not covered in this article.
Look for “pure maple syrup” or “organic maple syrup” on the label before purchasing to make sure it’s the real deal.
Read on to learn some smart storage hacks for larger quantities, how to extend the shelf-life of your pure maple syrup, and what to do if you make your own maple syrup and notice it becomes cloudy or has sediment in it.
Can Maple Syrup Go Bad?
As with any food product, given the right conditions, an open bottle of maple syrup stored at room temperature can go bad within a few weeks.
Unopened maple syrup has a very long shelf life—easily six months to a year and often upwards of a couple of years. After a couple of years, maple syrup might start to darken and lose its flavor.Even if you don’t consume
A new bottle of maple syrup is naturally shelf-stable, without using any preservatives, because of the high sugar content found in the maple syrup.
Refrigerate After Opening
As with many types of food storage, you should refrigerate your bottle of maple syrup after you open it.
Maple syrup can be refrigerated in both plastic containers and glass containers. Store maple syrup in an airtight container.
Why Does Maple Syrup Go Bad
If made properly, maple syrup will last a very long time.
The number one reason maple syrup can go bad is because of mold.
Even though it sounds horrible to mention mold in maple syrup, the FDA considers maple syrup to be low-risk food, relatively free of microbial and pathogenic concerns.
Mold in Maple Syrup
Maple syrup can start to go bad when mold settles on the surface of the syrup. The kind of mold found in maple syrup is non-toxic and is not harmful to your health but does affect the flavor and appearance of the syrup.
Left unchecked, the mold will grow throughout the maple syrup. This is especially an issue when maple syrup is not made to the correct density—that is the syrup is too light (or has too much water content still in it).
Mold easily moves from the surface of the maple syrup throughout the body of the syrup when syrup is not of the right density. When this happens, you can see white wispy clouds in the syrup that resemble a ghost in the glass bottle.
You can easily correct this problem by gently heating the syrup to about 212 degrees Fahrenheit and then pouring the hot syrup through a filter into a clean container.
Use the same filters you used when making your maple syrup. Coffee filters or cheesecloth work too.
Keeping your opened bottle of maple syrup cold also helps prevent the growth of mold.
Let’s Test How Long it Takes Mold to Grow in Maple Syrup
I decided to test and photograph the different stages and appearance of the growth of mold in maple syrup.
For our test, I’m using two different bottles of maple syrup. Both bottles are left open, unrefrigerated, and sitting on our windowsill which receives moderate sunlight late afternoons.
We also keep our house temperatures around 68 degrees Fahrenheit during the day and 64 degrees at night.
The bottle on the left is pure maple syrup—although diluted about 15% more than expected with water to simulate the error of bottling your maple syrup before it reaches the correct specific gravity.
The bottle on the right is 100% pure and made to the correct density.

Mold Begins Growing After Just Two Weeks
It took about two weeks for mold to start a foothold in the maple syrup bottle on the left. Remember that was the syrup we diluted 15% to simulate a manufacturing mistake.
Look closely at the upper right corner of the bottle on the left and you’ll see the white whispy ghost-like structures of mold starting to form.
There are no visible signs of mold in the bottle on the right—the 100% pure maple syrup made to the correct specific gravity.

I don’t know about you, but I think it’s pretty good news that properly made maple syrup can last a few weeks open on the windowsill and not show any signs of mold.
I’ve zoomed in on the mold in maple syrup in the photo below so you can get a good look at what it looks like when it starts growing.

We let our test bottles of maple syrup sit on the window sill for another week. The total elapsed time for this experiment was just shy of one month’s time.
Remember how important it is to make sure maple syrup is finished to the proper specific gravity (density).
The bottle on the left was made incorrectly to a lower density or specific gravity. In less than one month mold has overtaken that bottle.
You can see that the bottle on the right does not have any mold starting to grow; even after one month of exposure to air and room temperatures.

Manufacturing Mistakes When Making Maple Syrup
Pure maple syrup is made by collecting sap from maple trees. The maple sap contains water, nutrients from the tree, and natural sugars.
Boiling maple syrup evaporates nearly 98% of the water in maple sap to create 100% real maple syrup; nothing extra is added.
The best time to collect maple sap is in early spring when the maple sap begins to run.
Sugarmakers (a sugarmaker is someone who makes maple syrup) have to be aware of the final specific gravity, or density, of the maple syrup.
Even pros make mistakes when making maple syrup. Color and density are the two most common mistakes made when making maple syrup, followed by taste and labeling.
Mistake #1: Syrup Too Watery
Oftentimes a hobby or craft sugarmaker boils their sap in pans over a wood fire. To prevent burning or scorching of the syrup, they remove the sap too early from the fire. As a result, the density of the maple syrup is off, and a bit of extra water remains in the syrup.
You can visually determine the density is off by pouring the cooled maple syrup and seeing if it looks runnier than it should be (i.e. not as thick).
Removing sap early when boiling over an open fire prevents scorching, but it also creates one more step for those who make maple syrup at home.
You’ll need to “finish off” the boiling process on your stovetop to ensure you have the correct density.
Mistake #2: Contaminated Containers
Use clean containers when bottling your maple syrup. We don’t recommend reusing containers.
It might be tempting to gift a bottle of maple syrup to your uncle using his favorite scotch bottle, but the chances of contamination are too high.
Used containers also often pass “flavors” of the previous contents to the maple syrup.
Mistake #3: Too Much Headspace in Container
Don’t leave too much headspace when filling your clean maple syrup bottles.
It’s important to fill the bottle to the very top. Don’t leave any extra room at the top of the bottle.
Signs of Spoilage
As soon as you open a bottle of maple syrup the high-sugar content begins to attract moisture.
This creates the perfect breeding ground mold.
Don’t worry, your maple syrup won’t immediately spoil!
You should be able to leave your maple syrup on the counter for a few days—but please, no more than a week.
Signs of spoilage include white wispy clouds floating throughout the maple syrup, off-flavor smells, or a thick film on the surface of the maple syrup.
How to Store Maple Syrup
Be sure to store maple syrup in clean, airtight containers. As mentioned earlier, mold is maple syrup’s number one enemy. That’s why you’ll often hear people say to store your maple syrup in a dry place.
Most people safely store unopened bottles of maple syrup in kitchen cabinets or pantries.
Keep Out of Direct Sunlight
Maple syrup bottles are often packaged with beautiful graphics and large print saying “100% Pure Grade A” on them.
Maple syrup producers, proud of their products, designed the packaging to look great showcased in your kitchen.
You might even be tempted to place it on your windowsill so that you can enjoy the beautiful color of the syrup.
But don’t do it. Extend the shelf-life of your maple syrup by keeping it out of long-term sunlight exposure.
Extend the Shelf Life of Maple Syrup By Freezing It
If you’ve got a large quantity of maple syrup that you want to store for a long period of time, you can put it in the freezer.
This works great for hobby sugarmakers who don’t want to bottle their syrup. You can safely store your maple syrup in large freezer storage containers.
Maple syrup stored in the freezer won’t freeze solid because of the high sugar content. But the maple syrup will expand. Be sure to leave a bit of headroom in your container for expansion. If you do not, your container can crack (especially in the case of glass), leaving a mess in your freezer. This is the only time that you shouldn’t fill your maple syrup bottles to the top.
Footnotes:
- Comprehensive Reviews, United States Department of Health and Human Services, Evaluation and Definition of Potentially Hazardous Foods
- Tucker Diego, Vermont Maple Conference Week 2020, Common Issues Found During Product Inspections