Concentrated fertiziler - how long is it good for?

[JeffreyR]

I have been using an MSU dry fertilizer and mix it up for each round of watering. With the few plants I have, I may be measuring eights of teaspoons. Then I have to wait for it to dissolve.

I've read that a good approach is to mix up a batch of concentrated liquid fertilizer and then dilute that as needed to make your watering solution. You only have to measure the powder once, it gets dissolved, and you are much less likely to make errors due to measuring small amounts.

My question is, do I have to worry about that liquid fertilizer concentrate spoiling or going bad in some way?

I’m growing mainly Phals, indoors, at the present time, and they are doing well... Consistently growing new leaves, spikes, roots, flowers. Very little in the way of pests or disease.

Thanks in advance for helping a beginner.