Can I use neem oil on plants is a valuable question for gardening enthusiasts. Sadly, this oil has an expiry date and must be used within a specified time. Expired oil is unhealthy for plants and might cause more harm than good.
Discover how to tell if neem oil is rancid and other helpful information in the article given below.
- Can You Use Expired Neem Oil on Plants?
- How to Check if Neem Oil Has Expired?
- How to Store a Bottle of Neem Oil Before It Expires?
Can You Use Expired Neem Oil on Plants?
No, you cannot use expired neem oil on plants, and this is because the expired oil becomes rancid and then harms the plants and might even kill them. It should no longer be used to make foliar sprays and soil drenches for household plants and vegetables.
– It Will Be Ineffective
The compound that gives a neem oil spray its pesticidal properties is Azadirachtin. It starts decomposing right from when the oil is cold pressed until it becomes rancid after two to three years. This means that the oil slowly loses its properties over time and eventually becomes useless by the end.
That is why it is wise to buy a small bottle of freshly pressed oil to be used on plants. In short, you should opt to finish this bottle as required in a short span of four to six months, and then buy a new one, so getting a small bottle is a good choice. The oil near or past its expiry date will not help plants with pests or fungal attacks, and this way, it will not be as beneficial as a fresh one would be.
– May Harm Plants
Expired oil from the neem tree turns rancid, and all its active ingredients break down into smaller ones. Some breakdown products are useless, while others might be downright harmful.
When light falls on the oil, the breakdown products include free radicals and oxidative compounds. This way, it will be more damaging and corrosive to the plant and the way that it would prosper as this will lead to hindrance of the plant’s life.
These harmful compounds break down the cell membranes of the plant. They enter the plant’s vascular system and interfere with photosynthesis and gaseous exchange. The oil that is way past its expiry date might even cause severe toxicity and even death of the plant.
How to Check if Neem Oil Has Expired?
Check if neem oil has expired by checking for discolorations, foul odor, and the presence of lumps in it. Before applying neem oil to plants, it is essential to ensure it is still healthy and fresh. Once it has been emulsified, it expires within 6 to 12 hours.
This oil expires when the Azadirachtin compound within it starts breaking down. Neem oil is composed of more than 140 compounds identified so far. The most important compounds that contribute to its pesticidal and anti-fungal effects are Azadirachtin, Nimbin, and Nimbidin. Azadirachtin is the primary compound responsible for killing plant pests, and when it breaks down, the oil becomes a less effective pesticide.
Exposure to high temperatures and moisture in the air speeds up the oil breakdown process. This is why stored oil might last for up to three years, but an open bottle barely lasts six months. Once this oil is mixed with water, it breaks down faster and expires in less than a day.
– Check for Any Discolorations
Simply looking at expired oil will tell you it has turned rancid and unfit. If your bottle is dark, pour some oil into a transparent or white bowl to inspect it closely. Regular oil is yellow or yellowish-brown, while some varieties are even golden or reddish-colored.
If the oil looks pretty dark in color, like dark brown or black, it is most definitely expired. Sometimes the oil is still yellow, but white clouds float in it. This is also a cut sign of contamination and rancidity. You can also compare the current color of the oil to how it was when you first used it.
These compounds are unstable and eventually break into more minor ones over time. As a result, the efficacy and potency of neem oil as a plant pesticide and fungicide decreases. So if you check and see that the color has become much darker in its shade, this is how you will know that it has aged, which is a crucial feature to look for.
Some of these more minor compounds are downright harmful and harmful to plants. Other combinations are responsible for the emanating lousy odor from an expired oil, so be sure that you would dispose of it rather than trying to use it because it will not benefit the plant in any way possible.
– Check for Unfavorable Smells
Neem oil typically emanates a strong and pungent smell similar to that of garlic and sulfur. Some varieties of fresh oil have an earthy aroma that is closer to that of nuts, like peanuts.
Once it expires and turns rancid, it will lose its strong scent and instead smell bad that would be quite foul, and just as you smell it, you wouldn’t want to use suc a product on the plant any longer. An immediate whiff of the oil bottle will tell you whether it has gone wrong, and you should not be used as it can damage the roots.
Neem oil smells last for about two years in an unsealed bottle. Once the oil has been applied to the plants in spray form, its spray lasts around two to three days but is less intense. The smell of pure oil lasts for about five days, which is how long does neem oil smell last. On the contrary, the scent is not the same when the bottle has been left after it is opened, it is less earthy and more pungent.
– Viscus Texture
Oil is naturally liquid and should be uniformly smooth and velvety in texture that seems to be more viscus. This particular oil is quite heavy and denser than most other oils.
The development of lumps and solid grains means that it has gone awful, and even it doesn’t feel the same as the fresh ones are. Another sign is that the oil will separate into different layers clearly visible and vary in color that you will see when you examine thee liquid in a still state, not mixed.
In such a case, you must get rid of it, and when it comes to how to dispose of neem oil, you should see that after it expires or turns rancid, neem oil should be disposed of in a pit away from underground water sources. Alternatively, mix it with an absorbent material like kitty litter and throw it away in a sealed container. Ask if your local waste disposal accepts expired oils or not.
– Use Emulsified Oil Within a Day
Once the neem oil concentrate has been emulsified, it must be used immediately. Studies show that the mixture of an emulsified oil with water tends to expire within 12 hours. It will expire even faster if the surrounding temperatures are higher or it has been exposed to bright light.
Once the emulsified water is mixed with water for a plant spray, it is better not to use it again. That is why we recommend our readers to make only as many solutions as are needed at the time and will not go wasted. Over time, the oil again separates from the water and expires faster.
Emulsification is breaking oil into smaller particles to mix with water. For this, it is either thoroughly mixed with liquid soap or silica powder. Naturally, this means that the already ongoing breakdown of soil is only accelerated further, and it will fail to be doing so because it has expired and is no longer safe.
How to Store a Bottle of Neem Oil Before It Expires?
Store a bottle of neem oil before it expires in someplace cool, dark, and dry before its expiry date. Ensure it comes in a dark, opaque plastic bottle or glass jar with a tight lid. Store it at room temperature, around 80 degrees Fahrenheit, instead of in the refrigerator.
– Store in a Cool, Dry Place
After purchase, keep this oil in a cool, dry, dark place within the house. Ensure that the oil you bought is from a trusted manufacturer with a precise expiration date. Its bottle itself should be dark and opaque so that no light passes through it.
A pantry or a drawer in a dark room or corner is the best place to store oil long-term. Even though the oil bottle has an expiry date, the oil will turn bad faster if the bottle is transparent and is stored someplace well-lit. It will also expire more quickly if its bottle is left accidentally open and exposed to air, so be sure to close it very well and keep it away from lights.
– Protect It From Extremes of Temperature
Ideal neem oil storage temperatures are around 77 to 80 degrees Fahrenheit all year round. Temperatures higher than this will accelerate the breakdown and expiry of this oil. Below 70 degrees Fahrenheit, the oil has begun to solidify into a hard mass that must be melted before use.
However, it will remain stable and potent even at colder temperatures, around 40 degrees Fahrenheit. Neem oil lasts two to five days on plants when used in spray form mixed with water.
The potency of neem solution decreases by 50 percent every 24 to 60 hours on average. That is why it is recommended to use this oil on plants at most twice a week, if you are wondering how long does neem oil last on plants.
– Do Not Store it in a Refrigerator
Storing oil in a refrigerator is not a good idea at all and will only prolong the shelf life up to two to three years. In a refrigerator or a freezer, the oil will turn into a solid mass that must be melted before use.
Never heat this oil to melt it, as it harms the plants, and this is also the same case before they begin to come closer to the expiration date. Instead, leave the oil at room temperature until it turns into liquid.
– Check The Expiration Date
Storing neem is difficult because even properly sealed bottles last only about two to three years maximum. This is only when the oil is bought from the best sellers and stored under perfect conditions.
Once the seal on the bottle is broken, it will deteriorate rapidly and last from six to 12 months maximum, so be sure to store them the right way. After the oil has been mixed with water, it does not last more than eight hours.
To sum it all up, neem oil should never be used on a plant after it has expired, so here we have a little recap:
- Sealed oil has a life of around three years, while unsealed one lasts for barely six months.
- The older the oil, the less effective it is, and it becomes totally ineffective past the expiry date.
- How long neem oil lasts also depends on the conditions in which it is stored.
Expired oil is not an effective pesticide and might cause harm to the plants instead. Be wise and go for a smaller bottle that you can finish within six months.
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