I just bought an ornamental kale and I wanna know if I could keep this as an indoor houseplant, for how long and how often should I water this plant.
alidm, I am sure that you can keep it indoors "but I do not know for how long", quoting my doctor on the question 'will I live?'.
Seriously, the plant thrives in full sun, nitogen and lots of water (like so many leaf crops). Indoors, under the reduced lighting, the watering and nitrogen ought to be cut back. I certainly would not allow the soil to dry out. It will "bolt" at which time the plant should be discarded.