Answer: Whenever you spray something, it is a good idea to test the spray on just a couple of leaves and wait a few days and make sure there are no ill effects, then go ahead and spray the whole plant.
If using a soap, it is important to use a commercially formulated insecticidal soap and read and carefully follow all of the label directions. A solution of half soap and half water would be way too strong to use on any plant -- no matter what kind of soap you were using.
Having said that, now that the damage is done, you will have to wait and see if they recover. I'm really sorry about your morning glories.
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