Caren White is a Master Gardener and instructor at Home Gardeners School. She has been associated with Rutgers Gardens for over a decade.
What is Cast Iron Plant?
Cast iron plant (Aspidistra elatior) is native to Taiwan and southern Japan. It is related to asparagus. Like asparagus, it grows from an underground rhizome. The leaves grow directly from the rhizome rather than from vertical stems.
The plant earned its name “cast iron plant” because it thrives on neglect. It happily lives in the dark corners of your home or patio, rarely requiring water. In fact, if you forget to water it and the rhizome becomes dried out, you can bring the plant back to life simply by watering it and rehydrating the rhizome which will then start growing new leaves.
Cast iron plants grow to 24 inches tall and equally wide with dark green leaves. Newer cultivars have white and green variegated leaves, yellow and green striped leaves or white tipped leaves.
The plants’ flowers are difficult to see because they develop at the base of the leaves. They are a cream color with maroon coloring inside. Bloom time is early summer. You will not see seeds on your plants because the flowers are only pollinated by fungus gnats that are native to Taiwan and southern Japan.
How to Grow Cast Iron Plants Outdoors
Cast iron plants are hardy in zones 6 – 11 so they can be grown outdoors year-round in those areas. They are shade plants. If you plant them in the sun, the leaves will first scorch (turn yellow then brown) and then die. Find a shady corner in your garden or on your patio if growing in containers. The north side of your home should provide enough shade to keep your plants happy.
Cast iron plants are not fussy about soil as long as it is well-draining. Overly wet soil or over-watering will result in root rot which will kill your plant. Let the soil dry out between waterings. Use your finger to determine if the top one inch is dry. If so, then it’s time to water again.
Cast iron plants are heavy feeders which means that they need a lot of nutrients. Plan on fertilizing your plant every two weeks with a liquid all-purpose fertilizer during the spring and summer growing seasons. You can use a time release fertilizer in place of the liquid fertilizer to save time. There is no need to fertilize during the fall and winter when the plant is resting. Don’t worry if you don’t see a lot of growth after fertilizing. You don’t need more fertilizer. Cast iron plants grow very slowly.
How to Grow Cast Iron Plants Indoors
Cast iron plants can also be grown as a houseplant whether you live north of its hardiness zone or not. They are shade plants so they are perfect for a dark corner where nothing else will grow or in a room with north facing windows. They also don’t mind a dry environment, a problem with other houseplants for which you need to either mist or create a humidity tray. Cast iron plants don’t care how dry your house is.
They do care about soil. Make sure that the potting soil you are using has a pH of 5.5 to 6.5 and drains well. The pot you use must have a drainage hole. Over-watering or waterlogged soil caused by lack of drainage will result in root rot which will kill your plant. Wait until the top inch of the soil is dry before you water.
Cast iron plants are heavy feeders. They need lots of fertilizer. Unfortunately, one of the facts of life when growing plants in pots is that every time you water, you are leaching nutrients from the soil. Use a time release fertilizer or water every two weeks with a liquid all-purpose fertilizer. You can fertilize less frequently during the winter when the plants are resting.
Don’t expect to see a lot of growth on your plant. Cast iron plants grow very slowly. In fact, you may only have to repot your plants into larger pots every 4 or 5 years. You will know it is time to repot when you see roots growing over the edge of the pot. Repotting should be done in the spring when the plants have resumed growing after their winter rest.
How to Divide Cast Iron Plants
While you are repotting your plant is an ideal time to divide it if you want more plants or want to share with friends. Just break apart the rhizomes. Make sure that each piece of rhizome has at least two leaves attached. Repot the new pieces in fresh potting soil and water well. Keep your new divisions moist and warm. When you see new growth, you will know that your division has roots and can now be treated like any other houseplant.
© 2020 Caren White
Caren White (author) on June 14, 2020:
I'm glad that you found it helpful.
Danny from India on June 13, 2020:
Caren, this is a very interesting piece related to gardening. I wasn't aware of such a method. Will try at my place as I am into indoor gardening too.