hello, i usually mix up my nutrients in a watering can and then feed my plants. However because of the seize of the plants there is usually a lot left over in the watering can. I know i should just use less water and nutes when mixing up but i dont really wanna be dealing with fractions of a milimetre. My question is this. Can the nute solution be left in the watering can for several days and then be used on the plants or do the nutes degrade if left for a few days? hope this question makes sense. Thanks

You could probably get away with doing so with a solution of solely chemical salt ferts, but I wouldn't have thought it a good idea with organic nutes due to bacterial/fungal action on them.

Just measure out less when you're doing it - use a measuring syringe or a pipette to measure out small amounts.