Hi Dave,

You really don’t have a Cast Iron Plant. If the leaves are solid green, your plant is a Dracaena janet craig. If there is a faint yellow stripe in the leaves, your plant is a Dracaena Corn Plant Dracaena massengeana) It looks like the leaves are turning a muddy brown color; is that right? That would indicate the plant needs more water. At this point I would cut off the top leaves and include about 5″ of stem; remove bottom leaves that are dying.  Plant it in a 6″ pot of good soil (I like Miracle Gro potting soil). Be sure there are drip holes in the bottom of the pot. Water well, until the water drains out the bottom of the pot. Place in medium bright lightVery few houseplants should be placed in direct sun. High light refers only to bright indirect light since direct sun often burns the leaves of indoor houseplants. An area that is too hot and dry encourages Spider Mites and causes blooms to quickly fade. A northern exposure really doesn't provide enough light for high light plants. These plants need to be placed directly in front of an east-facing window, within 1-3 feet of a west-facing window, and within 5 ft. of a south facing window. A high light area has over 300 ft. candles of light., no direct sun. Do not feed. Water again when the top 50% of the soil has dried out. Do not feed until the spring. Water the stem section that remains in the original pot well, until the water drains out the bottom of the pot. Follow the same instructions as I gave you for the new cutting. New growth should appear in about a month.

You can see a picture of a healthy Dracaena janet craig and read all my care tips for it in the Popular Houseplant section of the website.

https://www.houseplant411.com/houseplant/dracaena-janet-craig-plant-how-to-grow-care