Most insecticidal soaps can be used up to the day of harvest with a washing. If your product has other ingredients in it, you will need to go by what the label says.

What's eating your greens, do you know? IS will only work if it is still wet when it comes into contact with the susceptible insect.

Spray in morning or evening per rhizo's caveats. Only works if you contact critters, little repellency.

Dan

With salad greens, the munchers are most likely a caterpllar of one kind or another. Some dine during the day, others at night. Go out & look. Dispatch on sight.