Better to use water retentive granules mixed into the compost from teh start and then water generously in the evening so they can soak up the excess and release it by day. In very hot or windy spells, water again early morning before going to work or doing other jobs.
Most hanging basket plants are half hardy and aren't going to enjoy being doused with ice cubes although they're better than nothing.
Well, we'll have to agree to disagree. I don't use any chemicals agains aphids or other pests apart form wildlife friendly pellets for slugs and snails.
Soapy water is indiscriminate and bad for beneficial insects such as hoverflies and ladybirds which will eat thousands of aphids and maintain a balance if left alone. I feed the birds all year and the parents hoover up aphids and caterpillars to feed their young in the nest. More natural balance.
I dunk hanging baskets ina big bucket to give them a good soak.
Just keep watering in the evening - forgot to put gel crystals in my baskets this year but I'm finding that watering in the evening seems to work OK for them.