How to Care for Cast Iron Plants (And Keep Them Healthy)
Cast iron plants are aptly named due to how resistant they are to various forms of neglect. Although they’re one of the easiest plants to care for, unfortunately, this means they are also one of the easiest plants to forget. To help you avoid that pitfall, here is a step-by-step guide on how to ensure your cast iron plant is as healthy as possible!
Cast iron plants grow best when they’re 1) in terracotta pots 2 inches larger than their roots, 2) in well-draining soil, 3) watered when almost fully dry, 4) given 6+ hours of indirect light, 5) around temperatures of 60–75°F, 6) in 40% humidity, 7) fed liquid fertilizer in spring and summer, and 8) rarely pruned.
Aspidistra elatior, or cast iron plants, have served as reliable and handsome houseplants since the late 1800s. After reading this detailed care guide, you’ll probably see why!
Here’s a summarized knowledge card on cast iron plants and their growing requirements.
Common Name | Cast iron plant |
|---|---|
Scientific Name | Aspidistra elatior |
Perennial/Annual | Perennial |
Ideal Planter | Terracotta pots 2 inches larger than plant roots. |
Ideal Soil | Well-draining soil with 40% coco coir or soil, 30% orchid bark, and 30% pumice. Soil pH must be between 6.5–7.5. |
Ideal Watering | Water when the soil is almost completely dry. Reduce water in the winter. |
Ideal Light | 6+ hours of indirect sunlight near curtained north or east-facing windows. |
Ideal Temperature | 60–75°F. Avoid temperatures under 40°F. |
Ideal Humidity | 40% |
Ideal Fertilizer | Use general water-soluble fertilizer every month in the spring and summer. Avoid fertilizing in the winter. |
Ideal Pruning | Pruning can be done in the spring but is best avoided. |
More information can be found below. Without further ado, let’s continue!
1. Planter
Cast iron plants grow best in terracotta pots no more than 2 inches bigger than the plant’s root system to prevent overwatering. Once the plant’s roots are seen through the drainage, repot the plant in a container two sizes up.
Cast iron plants rarely grow over 3 feet (91 m) tall and can handle being potbound, so they don’t need large planters.
It’s best to keep them in pots only a couple of inches larger than their root system, as these pots are less likely to retain excessive moisture.
Another great way to avoid high water retention is to grow them in containers made of porous materials, like terra cotta. Conversely, plastic or glazed ceramic pots hold more moisture and are a better choice for those who often forget to water their plants.
Regardless of what type of pot you select, it must have drainage holes. Aside from allowing extra water to drain, these holes will let you see whether the plant needs to be moved.
At some point, their roots will outgrow the pot eventually. By that time, you’ll see the roots start to grow through the drainage holes.
When this happens, your cast iron plant is ready to be repotted and moved to a planter 1–2 inches larger than the previous one. These plants usually grow slowly, however, so you’ll only have to do this every 3–5 years!
2. Soil
Well-draining soil mixes with amendments like pumice and orchid bark are required for healthy cast iron plants. The soil does not need high levels of nutrients and can be between 6.5–7.5 pH.
These plants aren’t picky when it comes to their growing medium and don’t need anything too rich, so you don’t need expensive high-quality soil to grow them.
What you do need to worry about is root rot, since it is one of the most common fatalities of Aspidistra elatior. To combat this ahead of time, I suggest using a well-draining potting mix.
A good soil mix that can be made at home for cast iron plants would include 40% coco coir or regular soil, 30% orchid bark, and 30% pumice or perlite.
Moreover, you can grow them in various pH levels between 6.5–7.5 and use whatever soil amendments you have available. Just make sure it provides plenty of aeration and doesn’t hold on to moisture for too long.
3. Watering
To prevent overwatering, cast iron plants must only be watered when their soil is almost completely dry. These plants are drought-tolerant and must be kept out of soggy soil. Water them during the day with tap water or distilled water and avoid watering them during the winter.
Thanks to their rhizomes, these incredible plants are drought-tolerant and can survive more than a week without water if necessary.
Ideally, though, it’s good practice to water your cast iron plants as consistently as you can. You can water these plants during the day with regular tap water and water them from the top to flush out excess minerals.
Alternatively, you can water them with distilled water or rainwater. These are great options that contain lower amounts of minerals and sodium.
It’s usually safer to underwater Aspidistra elatior specimens rather than overwater them. Allow the roots and soil to dry out almost completely before watering them again.
When in a pinch, you can always insert a wooden skewer in the soil and pull it out to see how wet or dry the stick is to determine the soil moisture. You don’t want to water your plants in the winter, however, as they tend to go dormant.
For full accuracy, use this moisture meter from Amazon to help you properly water your cast iron plants.
4. Light
Cast iron plants are perfect for low-light homes and can survive with 6 hours of filtered sunlight daily. Their foliage cannot handle direct sunlight and grow best in partial shade near eastern or northern windows.
Sometimes called the beer plant due to their ability to tolerate dark bar-like settings, cast iron plants can survive in a wide range of lighting conditions.
Unlike many other houseplants, cast iron plants can be positioned up to 5 feet (1.52 m) away from north or east-facing curtained windows. These are pretty shady locations, but your plants will still be happy there!
Many cast iron plants cannot handle direct sunlight. You can grow them in almost any part of the house, as long as they receive at least 6 hours of dappled sunlight.
5. Temperature
Although cast iron plants can tolerate a wide range of temperatures, they are not frost-tolerant and must be protected from 40°F or less. Keep them in warmer temperatures between 60°F and 75°F for healthy growth.
Unless you live in an extremely hot or cold climate, you probably don’t have to worry about temperature requirements.
Every day temperatures around 60–75°F (15–23°C) will be perfectly fine for this low-maintenance plant.
But if the temperature consistently drops below 40°F (5°C), the cast iron plant could potentially die, especially if wet.
The foliage of cast iron plants are sensitive to frost and can be damaged by winter winds. Avoid drafty rooms with cold windows. Entryways and hallways can also be a source of cold wind and are not ideal.
6. Humidity
The ideal humidity range for cast iron plants is around 40%. This plant species does not need extra maintenance and can be grown in a room with a humidifier if needed.
Many households in the US have an average humidity level of around 40%, which is completely fine for cast iron plants. However, this will depend on where you live and your climate, so this number could vary daily.
Misting may be tempting, however, this does not effectively boost humidity and can invite mold or increase the odds of the plant getting a fungal infection.
Read more in our article: Orange Mold Growing on Indoor Plant Soil? (The Different Kinds and Causes)
In the scenario your humidity is too low, consider using this humidifier from Amazon that automatically works in the background!
7. Fertilizer
Since cast iron plants are not heavy feeders, they only require monthly feedings in the spring and summer with a 10-10-10 general liquid fertilizer. Granular fertilizer can also be used. Avoid feeding during the winter to prevent fertilizer burn.
Remember, these plants have a reputation for thriving in poor conditions and do not need anything fancy. They can easily be kept healthy with a well-balanced 10-10-10 fertilizer.
Pro Tip: Many plant owners have noticed more lush green growth in their cast iron plants after using kelp fertilizer. Fish emulsions can also be used for similar results!
Winter fertilizing can lead to fertilizer burn and damage the plant while it is inactive, so hold off on the fertilizer during the colder months.
Alternatively, you can also mix a teaspoon of granular fertilizer in the soil when repotting them or sprinkle it over the top of the soil for consistent feeding.
8. Pruning
Cast iron plants are best pruned in the spring and summer with clean scissors. For optimum results, avoid pruning this plant as its foliage tends to grow slowly.
These plants are truly the definition of no-fuss and can live in houses for years without pruning. It’s recommended not to cut more than a few leaves at a time unless absolutely required.
Cast iron plants are known to be quite slow to replace lost leaves. If you must prune them, I suggest doing so while its actively growing, in spring or summer.
Maintain a tidy appearance by removing spent and withered leaves with a clean pair of shears. Cut it as close to the soil as you can and keep as much foliage as possible.
With the right care, you won’t need to prune your plant very often at all!
FAQs
Are cast iron plants toxic?
Unlike many houseplants, cast iron plants are non-toxic to humans, dogs, cats, and birds. These plants are used mainly for ornamental purposes, however, and are best left uneaten.
Can cast iron plants grow outside?
Cast iron plants are commonly used for landscaping and can be safely grown outside. However, they are not frost-tolerant and will die when exposed to 40°F for long periods. If possible, it is recommended to bring them indoors during the winter or cover them with a thick blanket for protection.
Summary of How to Care for Cast Iron Plants
Cast iron plants are popular houseplants that can survive neglect and need little attention. To keep them healthy, however, they are best grown in terracotta pots with drainage holes and well-draining soil that is watered when almost completely dry.
These plants can grow in various lighting conditions., except direct sunlight exposure. Cast iron plants grow best in light shade with 6+ hours of filtered sun. Humidity levels around 40% and temperatures around 60–75°F will be fine for cast iron plants, so long as they are kept away from frost.
Monthly feedings with general water-soluble fertilizer in the spring and summer will keep cast iron plants healthy. Although pruning is not needed, their damaged leaves can be removed in the spring with clean scissors.
Sources
- “Cast Iron Plant” by n/a in NC State University
- “Plant of the Week: Aspidistra elatior: Cast-iron Plant, Beer Plant” by n/a in University of Arkansas
