I have some Miracle Grow Houseplant fertilizer that was given to me several years ago. Since it has no expiration date. . .how long can I continue to use it before it is no longer effective? It's a liquid and you only use a few drops at a time so the stuff lasts forever. I hate to throw it away if it's still good but I also hate to use it if it's not going to benefit my plants. I also have some regular Miracle Grow fertilizer for my outside plants. I've had it for a little over a year and there are no "use by" dates on it either. Does fertilizer expire? Thanks! :)
With liquid fertilizers, there might be some crystallization over time. The solubility of fertilizer salts increases with increasing temperature, so heating a container of liquid fertilizer (by putting it in a pot of hot water) should dissolve any crystals. Otherwise, nitrogen fertilizers can degrade through loss of ammonia (a gaseous nitrogen compound) to the atmosphere. The ammonium compounds which are used as nitrogen carriers break down very slowly unless mixed with alkaline substances, but they may lose some weight and value over prolonged storage ... especially if their container is not well sealed. Some organic fertilizers can become moldy. Their nutrients may blow away as spores. -Tony
Thanks Tony. I think to play it safe I'll just get a new container of houseplant stuff. The outside stuff has been kept dry, is newer and is still sealed in the original package so it should be alright.
Straying OT... wild-rose-43, yours is an interesting question. I had asked this not with fertilizers but with rooting powders/hormones. If anyone knows the answer to that, I'd like to know. I ended up buying new powders - just in case.
