Here's another thought for "gradual watering" -- somewhat depending on how many plants you need to water... I often use ice cubes to water houseplants, they melt gradually instead of just running through the soil and draining out. (LOL -- I tend to let my houseplants dry out pretty much between waterings, doubt I've ever killed anything by over-watering!!) You might consider freezing some larger chunks of ice, like in butter tubs or whatever, to set next to the plants.
