Last Updated on October 31, 2021 by Phil
If you have a brown thumb or can’t seem to keep any houseplants alive, try the cast iron plant.
Almost indestructible, it can take a lot of abuse and neglect without dying on you.
Thus, making it among the most popular indoor choices for busy homeowners.
To learn how to care for the cast iron plant, read on below.
About Cast Iron Plants
“Hard to kill” and “nearly indestructible” are two common phrases used to describe the cast iron plant. That’s because it’s very resilient, lives long, and can tolerate a lot of neglect. It’s also able to survive in conditions that most other plants aren’t.
This is why this undemanding houseplant is perfect if you have a brown thumb or are just to busy to spend tons of time caring for it.
Its ability to thrive in low light conditions also makes it among the most popular choices for homes and offices where space by a sunlit window is often a luxury.
Like many houseplants, it is grown for its beautiful foliage rather than its blooms. Although it does produce cream purple-colored flowers, it’s its large, glossy looking dark green leaves that make it very attractive to look at.
Cast Iron Plant Care
Cast Iron Plant Light Requirement
When it comes to lighting, cast irons plants don’t like either extreme. As such, it’s not a good idea to keep it somewhere that’s completely dark or in the path of direct sunlight. But, anything in between works just fine.
This makes it perfect for areas experiencing low light including those with partial shade as well as filtered or dappled light.
Indoors, this means keeping it at least a few feet away from the window. The exception is if the window is facing north.
This is also why it’s a popular plant you find in offices where fluorescent lighting from the ceiling is enough to keep it healthy.
Outdoors, you can place it in areas of your garden or patio that get a lot of shade or right under trees as ground cover.
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Cast Iron Plant Temperature & Humidity
Being native to Japan and Taiwan, they can tolerate a wide range of temperatures ranging from 45 to 85 degrees Fahrenheit. That’s because these two countries have warm summers but also cooler winters compared to many other tropical and subtropical locations.
That said, given a choice they’d prefer a much narrower temperature range of between 60 and 70 degrees. This is why you’ll see cast iron plants grow best in zones 7 to 11.
The best thing about it is that while it thrives during the hot summer months, it isn’t easily damaged when the mercury drops during the winter. Still, it’s a good idea to keep it away from frost or provide it with insulation or protection from the cold once temperatures drop below 40 degrees. Otherwise, it can sustain damage to its leaves.
Similarly, keep it away from cold draft and wind chill.
As with temperature, cast iron plants aren’t too picky with humidity either, While they enjoy high humidity, they’re fairly happy without it.
These two features, along with their ability to grow in low light conditions makes them ideal house and office plants.
Cast Iron Plant Watering
Just like they don’t need a lot of sunlight, cast iron plants also don’t need a lot of water. If you live in cooler climates and keep it away from sunlight, you’ll notice that it will only need watering about once every two weeks.
That said, don’t forget to water them. While they’re drought-tolerant, allowing them to get dehydrates is not a good idea.
But, more importantly, never over water it. This is the one sure way you can hurt or even kill it.
To a degree, you can waterlog is it’s kryptonite. Like Superman, the cast iron plant is almost indestructible no matter what conditions you put it in. And, it’s fairly pest and disease resistant. However, water is the one weakness that can take it down.
To help prevent this from happening, allow the soil to dry out before watering. You can easily test this by inserting your finger into the soil. If the top 2 inches feel dry, it’s time to water.
But, if it feels moist, then wait.
Similarly, making sure that your container has drainage holes is key. And, always dump any excess moisture that collects in the saucer underneath your pot, since this will keep the soil wet as well.
The type of soil you choose for your cast iron plant will depend on whether you’re growing indoors or outside. And, if you’re placing it in a container or planting it right into the ground.
For indoors or in pots, go with good potting soil. Outdoors, it will be happy with sandy or clay soil.
Either way, use soils that’s slightly acidic (pH between 5.5 to 6.5) and drains moisture well.
Also, give it some extra space.
That’s because it has a rhizomatous root system that likes to spread out. While it takes time because the plant is generally a slow grower, it grows outward and takes up space to its sides.
As such, placing it in a pot that’s a couple of inches wider help accommodate it. Similarly, when planting outdoors, leave about a foot of free space between them.
As with water and sunlight, the goal here is not to overfeed your cast iron plant. While it does appreciate some nutrients, it’s actually more afraid of too much fertilizer.
In fact, if you see it start losing its variegation or your leaves turning plain dark green, then it’s a sign that you’ve applied too much plant food.
That said, use a balanced houseplant fertilizer. You can go with a slow-release or liquid formulation. But, do water it whenever you feed it in order to prevent fertilizer burn from happening.
Do so once every 2 weeks during the spring and summer. And, stop when fall and winter come around.
If you don’t like doing any extra work, then you’ll be happy to know that you don’t need to prune this plant.
When you do, it will only be for appearance purposes or to remove any pests or insect damage. Beyond that, you won’t really need to take out your pruning shears.
Cast Iron Plant Propagation
The most common way these plants are propagated is with root division. The good news is, while you do need to get your hands a little dirtier than stem or leaf cuttings, it’s still a fairly straightforward process.
Here’s how to do it.
- Gently remove the plant from its pot. Make sure not to jar it, even if it feels stuck. If it’s in a pot, turn the pot sideways and slowly coax it out. If it’s in your garden, then you’ll need a shovel to dig it out. Either way, be careful not to shock or cut it.
- Next, dust off any extra soil from the roots and extend the tips outward using your fingers.
- Choose the clumps you want to divide. The best ones come with 2-3 stems or more.
- Put each clump into its own container. Make sure to plant it such that it ends up in the same height that it was before.
- Within the next 6 weeks, you should start seeing new growth.
Repotting Cast Iron Plant
As with many of its other features, cast iron plants are likewise low maintenance when it comes to repotting. In fact, you’ll likely only need to do so every 3 years. And, in most cases, it’s to refresh the soil it’s in.
in addition to giving it some fresh soil, the only other time you’ll need to repot is when its roots start growing over the edges. This is a sign that’s it has outgrown its container.
If you do so, it’s a good idea to do it during springtime. But, it’s worth noting that the plant isn’t a fan of moving.