I have used MG for tomatoes that I could swear was 5 years old. I have fertilizer for flowers that are even older. Today I found the tomato plants looking pretty sad. We had 3.5 inches of rain or more in one weekend, over 4.5 inches in the last 2 weeks or so, followed by temps in the 90s. The leaves looked pale with some dry brown areas of speckling. The definitely looked like they needed some nitrogen. I had some left over MG pink stuff and 2 containers of Urban Farms Texas Tomato food. One container was 3 years old and had been stored in the garage. The second container is two years old but I stored it in the house all winter. I shook the 3 year old TTF for a minute or two and there was no sediment on the bottom. Ask me how I know. I spilled some on my shirt and pants trying to tip it far enough to see the bottom. Then I found the one I stored in the house, I didn't bother to shake that up because I decided to use the MG for the first application simply because it has more nitrogen in it and I thought that they really needed a good shot of nitrogen.

But since I am going to try to fertilize more regularly than I usually do this year, would you bother using the old TTF? I am almost out of MG so I am going to get some just because I like to keep a little on hand. But that TTF is expensive. I hate to throw it out, but I would rather do that than go through the effort of using something that isn't going to help the plants much. I need to start putting a date purchased or opened on stuff when get it or use it the first time. That is how I know one TTF is 2 years old, because I did put the date on it. I only bought it twice, two years in a row, and the one in the house is dated 2019 so I know the other one must be 2018.

Besides the TTF, should I throw everything else out? I have old fish emulsion, Bloom Booster blue stuff for flowers, all in one Bayer fertilizer for roses that I stopped using because I heard it was bad for bees. I have several bottles of that. I would have to find out when the town is collecting stuff that can't be put in the trash to even get rid of that. Seriously time for a clean out but I just am not sure what to toss and what to keep. Hence the resulting pile up of old stuff.

Sue, if you are worried about it - get rid of it. Otherwise use it. As an Internet friend - that's my advice - same advice I would give to a 56 year old friend. (My age).

Looking at the labels [mention]Sue_CT[/mention], I do not see a lot that would turn into something toxic. The TTF maybe less effective due to die off of some of the Mycorrhizae, but the NPK and trace minerals should not be affected. Your choice not a lot I see to worry about. Fish emulsion should still be good unless it got some water in it, which would dilute solids and allow bacterial growth and would have an obvious non-fishy smell. If you want to post photos of labels, some may be able to give you clearer directions

Not so worried about anything turning toxic as much as just being ineffective, except the Bayer, which contains insecticides. I don't think that can be disposed of in regular trash, but I will check the label. I have never seen "use by" dates or anything on fertilizer, so maybe it is good and effective forever. I just didn't know.

I agree with Whwoz, unless it got wet and funky, NPK and minerals should be good indefinitely.
I have odds and ends of stuff way older than 2-3 years and still use it as needed.
OTOH I also have odds and ends that did get rained on or funky, and those belong in the compost pile.

I have used TTF that sat in my garage for a year (one reason I quit buying the gallon jugs!) and it certainly didn’t hurt anything.
You should be fine to use it up even if the live beneficials have died off.

[mention]Sue_CT[/mention] I did some Google research and many reliable sources agree that dry fertilizers do not expire unless that contain insecticides or herbicides and in that case they expire in 4 years.

Is TTF a liquid? If so, the sources say that an 8-10 year expiration is reasonable. Shake before using.

Worked 11 years in fertilizer manufacturing. Those who say that it's still the same if dry are correct. If it has gotten wet, some nitrogen may have been lost. Phosphate would remain the same and some potassium might be lost if it was wet to the point of leaching. In short, use it as if you bought it yesterday. The plants won't care how old it is.

Martin

Awesome, everyone, thanks!

We've been using the same container of 24-8-16 All-purpose Miracle Gro for many years. The copyright date on it is 2007; so, it's probably no older than that. Unfortunately, I haven't compared it to new Miracle Gro (which probably has a different formula anyway), but it was still capable of burning plants in 2015 or so (I haven't used it inappropriately since then).

Yeah, I haven't been much for using all-purpose fertilizer, but I'm trying to be more diligent about it, lately. I even fertilized most of my houseplants, today (with the Miracle Gro, in the soil).

Microelement chelates will degrade in time especially with light exposure. The main NPK will mostly remain the same, one should definitely not just throw chemical fertilizer, you can use it for your less important plants if you feel like your favorites aren't getting the best.