Does Roundup Go Bad Or Expire – SOLVED

If you’re anything like me, you’re constantly looking for ways to improve your lawn and garden without spending a small fortune. One of the best ways to save money on lawn care is by avoiding waste. It’s also a great way to minimize your impact on the environment.

Roundup is extremely useful when applied correctly. However, it can be expensive. So it’s tempting to make a single bottle last as long as possible.

Does Roundup go bad in storage? It’s only natural to wonder, especially when buying such products in bulk. Below I’ll explain whether or not Roundup will expire and provide some tips and tricks for proper storage.

Does Roundup Expire?

Roundup does not expire overnight the way, say, milk does. But it does lose its efficacy over time. Fortunately, Roundup products last for several years after purchase when stored properly.

If a bottle of Roundup is starting to go bad, you might notice the consistency change or a marked drop in how well it kills treated weeds. It is generally still safe to use such products but you may not get the expected results — i.e., you may need to treat the area several times or apply more product than previously required.

Roundup Shelf Life

The suggested shelf life of Roundup varies between formulas. Most formulas available at this time are advertised with expiration dates of either 4 or 8 years after purchase. Take note that formulas within the same product line do not always have the same shelf life.

Below are some of the most popular Roundup products and their expected shelf lives according to the manufacturer. While this list offers a brief overview of the average Roundup shelf life, you should always reference product labels or other official sources when handling and storing these herbicides yourself.

  • Roundup Ready-to-Use Weed & Grass Killer III — 4 years
  • Roundup Weed & Grass Killer Super Concentrate — 8 years
  • Roundup Weed & Grass Killer Concentrate Plus — 8 years
  • Roundup Ready-to-Use MAX Control 365 — 4 years
  • Roundup Concentrate MAX Control 365 — 4 years
  • Roundup Ready-to-Use Poison Ivy Plus Tough Brush Killer — 4 years
  • Roundup Concentrate Poison Ivy Plus Tough Brush Killer — 8 years

Does Roundup Go Bad Once Open?

Roundup will not immediately go bad after the bottle has been opened. On average, however, the product will not last as long as it would unopened.

While concentrated or pre-mixed Roundup kept in the original container usually lasts for several years, the same isn’t always true of product mixed after opening. I also don’t recommend storing any type of Roundup in a separate sprayer or similar container.

Most Roundup formulas are surprisingly resilient to changing temperatures during storage. However, it’s still best to store such products somewhere they will not be exposed to extreme heat or cold. This one simple step will maximize the lifespan of bottled Roundup, regardless of whether it is opened or not.

How Long Does Roundup Last Once The Bottle Is Opened?

Unfortunately, it’s impossible to know how long a bottle of Roundup will retain its strength once opened. Storing the opened bottle in a temperate location away from direct sunlight will likely make it last as long as possible.

If significant time has passed since the last time you used a particular bottle of Roundup, I recommend conducting a test patch before treating the intended area. Apply the product to a small area per the label and wait for the advised length of time for results to appear. If you do not see the expected results in the test area, it’s likely that Roundup has lost its potency. 

How Long Does Roundup Last After Mixing?

Again, how long you can expect Roundup to last after mixing varies between formulas. Proper storage after mixing also plays a large role in how well Roundup keeps in this situation.

As a general rule, diluted Roundup should not be stored for longer than 6 months. Even within this timeframe, it’s possible for diluted Roundup to lose its potency shortly after mixing. Personally, I prefer to mix only as much product as needed at a time rather than risk storing any leftover solution.

The good news is that mixed Roundup likely won’t cause any harm even if it goes bad. However, you won’t get the desired weed-killing results following its use. To prevent wasting valuable time, I suggest testing any mixed and stored Roundup before treating the intended area.

Will Roundup Go Bad If It Freezes?

Glyphosate has a very low freezing point — about -20°F, according to the University of Maine — and generally retains its potency once thawed out. In my case, I opt to store Roundup and other garden chemicals in my basement rather than my (unheated) garden shed.

You can safely store regular Roundup outdoors through winter as long as the container it’s kept in can withstand freezing. Be sure to let Roundup warm to above 32°F before pumping and spraying.

Some Roundup formulas contain more than one active ingredient. While glyphosate will hold up to freezing and thawing just fine, other chemicals may not fare as well. I recommend double-checking the label of your herbicide for storage guidelines for more information.

Does Direct Sunlight Affect Roundup?

Since Roundup is usually sold in opaque packaging, light exposure in and of itself is not a big problem. The real issue with storing Roundup in direct sunlight is the heat.

Roundup stored under high temperatures can evaporate. You might find that Roundup stored in a hot, sunny location thickens or clumps up in the bottle. This makes the product much harder to apply and could impact its overall efficacy.

How To Store Roundup At Home

For the best results, I recommend the following when storing Roundup at home. Adhering to the advice below will ensure safe storage and that all products retain their strength for as long as possible.

  • Store Roundup in the original bottle even after opening. If using the original bottle is not possible for some reason, select an opaque, airtight container instead.
  • Ensure the original label is stored with the product, even if it is no longer in its original container.
  • Store Roundup in a cool location away from direct sunlight. Keep away from freezing temperatures if possible.
  • Mark Roundup and other garden chemicals with the date of purchase so you can easily check how old they are.
  • Keep Roundup and similar products out of reach of children and pets.

You may also be interested in reading How To Dispose of RoundUp Safely

In Summary: Does Roundup Go Bad?

Technically speaking, Roundup can and will expire. But you can expect a bottle of Roundup to last for several years before showing any signs of going bad.

Even if you accidentally do use an old bottle of Roundup on your lawn or garden, chances are there won’t be any negative side effects. Expired Roundup will lose its potency but that’s usually it.