I am growing pole beans indoor for the winter. I planted them in Miracle Grow potting soil in pots about 10-18" deep. I'm pretty sure they have enough space. My question is when and if I should fertilize, and with what?
I doubt they'd need fertilizing. Though, if they actually reach maturity, I suppose you might try a one time watering with 25% strength of normal recommended dose of Miracle Grow.
Generally such experiments fail, but mainly due to the need for more intense light than what one can provide indoors.