pre-mixing fert and storing it

[MichaelNYC]

I use MSU fert (powder form that I dilute in water) and sometimes have leftover batches that I save for the next watering session. I wonder if this leftover stuff loses its efficacy?

The reason I ask is because I have mixed batches of Physan 20 and discovered that it quickly loses its potency in a matter of days.

But, then, you can buy liquid fert, which must originally come from solids, and its okay, right?

Any opinions would be welcome here. Thanks.

[Bikerdoc5968]

Physan-20 and RD-20 which are exactly the same products made by different companies specifically state on their label that: "Fresh solution should be prepared daily and when solution becomes visibly dirty." To the best of my knowledge, fertilzer remains stable. If your container is kept warm and there is evaporation, the concentration of the product would, obviously, change. Like you, I mix batches and hold it for the next time as do many commercial growers....what pain to mix exactly current needs everytime! But others may hold different opinions....

[Grandma M]

I usually mix up enough for 5 or 6 waterings. I stir it each time to make sure it is mixed well just in case anything sinks to the bottom of my container. I fertilize with each watering.

[MichaelNYC]

Thanks Biker and Grandma.

Oops, that Physan 20 label is now required reading!