by Nebula Haze
How long before nutrient water goes bad?
If you’re growing cannabis plants with nutrients, you may wonder, “How long does a nutrient solution last before it goes bad?” Will old nutrient water hurt your plants?
Making nutrient water can be time-consuming so you might want to make extra to use in the future. How long can a nutrient solution be stored before it needs to be tossed?
A few factors determine how long your nutrient water lasts before you should make more.
- Lasts a long time in a closed container with minimal air – Nutrient water is best stored in a container that’s filled to the top (as little air as possible) with the cap is on tight
- Countdown starts when nutrient water is stored with air – Once you’ve used up some of the water, there will be air in the container even if you close it tight. This closed environment with air and nutrient water creates a perfect home for microorganisms that make your water go bad
- Mineral-based nutrients last longer – Organic nutrients tend to go bad faster than mineral-based nutrients, but all nutrient water will go bad once the wrong environment is formed (microorganisms like nutrient water too!)
As long as your container is filled to the top and closed tight, nutrient water acts a lot like milk. It stays fresh a long time before you open the container. But just like milk, once it’s opened you’ve started a countdown until it goes bad. Also like milk, if nutrient water smells bad or looks different, it’s bad regardless of the “best by” date or how long it’s been stored.
So your nose and eyes are the final judges. If nutrient water looks weird or doesn’t pass the smell test, it’s time to make more.
Plants react poorly to bad nutrient water
How to maximize nutrient solution storage
Mixing nutrient water is time-consuming but making 1 gallon takes a similar amount of work as 5 gallons. That means you can save time by making a lot of nutrient water, then water plants as needed. This section will teach you how to make your nutrient water last as long as possible so you don’t have to make it as often.
1.) Cap on or off?
It may not seem like this would matter much, but the cap of the nutrient container actually makes a difference when storing nutrient solution. Here’s what to do to maximize storage.
- Screw the lid on tightly when the container is full (or close to full) to keep air out. A full container of nutrient water with the lid on tight kept in a cool dark place lasts for a long time. I’ve kept nutrient solution like this for weeks.
- Keep the cap unscrewed when nutrient solution is low because making it airtight at this point would trap too much air in the container. At this point, the nutrient solution will last longer if it gets access to fresh air. If nutrient water is trapped in a container with a lot of air, it creates anaerobic conditions that encourage microorganisms to grow. You’ll immediately be able to smell their yucky musk when you open the cap.
A completely full container of nutrient water with the cap on tight (and stored according to the instructions below) will last a long time.
Once the nutrient solution is low, the cap traps too much air inside and should be kept unscrewed to keep nutrient water from getting smelly
2.) Keep in cool place
Don’t let nutrient water freeze, but if you can keep the water under 70°F / 20°C then it will last a lot longer. The microorganisms that invade your nutrient water grow much faster in warm water.
3.) Keep nutrient water in the dark
Some of the stuff that can grow in your nutrient water uses light for energy like a plant. Keep your nutrient water in a dark place (you can even just throw a dark towel over the container) to make the nutrient water last longer.
Keep your nutrient water stored in a dark place and it will last longer
4.) Use mineral nutrients (i.e. no organic ingredients)
An ingredient is “organic” if it came from a living thing, and nutrients with organic ingredients tend to go bad faster. They’re more likely to be colonized by various bacteria, mold, and other microorganisms. On the other hand, mineral-based nutrients (sometimes called chemical nutrients) tend to last longer because there is no organic material. However, they’ll go bad eventually too.
I’ve recently been using the new 3-part 100% mineral-based nutrient system from Fox Farm called Cultivation Nation. So far my cannabis plants have been responding well to these nutrients but I’ll have more to say once I’ve finished a few grows with it (stay tuned).
I’m currently using the mineral-based nutrients from Fox Farm’s new Cultivation Nation trio. It does not contain any organic ingredients.
Cannabis plants have responded well so far!
5.) Take care of nutrient bottles
Sometimes your nutrients can go bad in the bottle. They might start growing something (especially with organic nutrients) or the chemical compounds might start crystalizing (especially with mineral nutrients). When nutrients “go bad” the problem is that some of the nutrients become unavailable to your plants. As a result, plants will get nutrient deficiencies even if you’re measuring out nutrients properly.
Keep bottles of nutrients fresh as long as possible
- make sure new nutrient bottles have a protective seal
- tightly close nutrient bottle lids after every use
- store bottles upright
- keep in a cool, dark place (but don’t let them freeze)
Always toss nutrients that…
- smell bad
- appear cloudy
- crystals have formed
- look/smell different from when you first opened them
This plant experienced nutrient deficiencies because the nutrient bottle had gone bad (crystals had formed, pictures below). Once the grower got a new bottle of nutrients the symptoms stopped spreading.
Double-check any nutrient bottles with crystals forming around the lid. It’s possible the liquid inside may have crystalized too (which makes nutrients unavailable to your plants).
Here’s an example of nutrients gone bad to crystallization. The nutrient solution on the left side is normal (mostly clear). Nutrients on the right side have gone bad (visible floaters when you stir)
That’s it! Now you’re an expert on this subject 🙂
Ready to learn more about growing?
