The top reason for yellowing leaves on a Cast Iron Plant (or any plant) is overwatering.
If your plant is standing in water or planted in heavy soil without good drainage, leaves are likely to yellow and fall.
Another reason for this problem is excessive light.
Cast Iron Plants are low-light plants.
Therefore, harsh sunlight will cause yellowing leaves.
To deal with this problem, prune away the yellowed leaves and correct your plant’s water, soil and location problems.
Why Do Plant Leaves Turn Yellow?
Leaf yellowing in plants is called chlorosis.
The reasons mentioned above are the most common causes of chlorosis in Cast Iron Plants.
But if you have ruled out these causes and are still having problems, there are a few other culprits you may wish to investigate.
Chlorosis In Cast Iron Plants: Cause And Effect
Cast Iron Plants are very rugged, and they can withstand low light and lack of water quite well, but harsh sunlight or overwatering can ring a death knell for them.
If you overwater your plant, it will give you a few signs before chlorosis sets in.
If you notice the leaf tips turning brown on your Aspidistra, evaluate your watering habits.
Remember that you are always better off underwatering a bit rather than overwatering at all.
The best watering method for Cast Iron Plant (and really for most plants) is the soak-and-dry method.
Here are the tips to water the Cast Iron Plant wisely:
- Water thoroughly, and allow the water to run through the drainage holes in the bottom of the pot.
- Let the soil become almost entirely dry before watering thoroughly again.
- If you have trouble judging whether or not the soil is dry, you can use a moisture meter to get an accurate reading.
- Just poke the meter into the soil deeply. It should go all the way to the bottom of the pot. When the meter reads “dry,” you know it’s time to water.
- Never allow your cast iron plant to stand in water, and remember to adjust the watering schedule with the changing seasons.
For example, plants typically need less water in the wintertime.
However, the exact opposite may be true if your home heating system tends to dry the air.
Water Quality Matters
Another cause for chlorosis in Cast Iron Plants is chemical sensitivity.
Tap water is typically full of chlorine and other chemicals. Be sure to use bottled, distilled, filtered, or rainwater for your cast-iron plants.
If none of these are available, you can let a bucket of tap water sit for 24 hours to allow most of the chemicals to dissipate.
When you do this, it’s best to use a container that provides a lot of exposed surface area (e.g., a bucket) rather than one that has a small opening that provides little exposure to air (e.g., a bottle).
Provide Excellent Drainage
- Always use pots and planters that have plenty of drainage holes.
- Use a light, airy, well-draining potting mix consisting of small gauge gravel or vermiculite and good organic compost.
Control Light Exposure
In nature, Cast Iron Plants live on the forest floor far away from direct sunlight.
That’s why, when kept as houseplants, they do so well in north-facing windows or even quite far away from the window.
In addition, they make excellent bathroom plants.
You can control the speed of growth of your plant by controlling the amount of sunlight it gets.
Bright indirect sunlight will result in faster growth.
A shady setting will result in slower growth.
Direct sunlight will result in yellow leaves and an unhappy plant.
Avoid Unnecessary Repotting
Another reason for yellowing leaves is transplanting stress.
If you repot your Cast Iron Plant too often, it may react with yellowing leaves, or it may even die.
These plants do not need frequent repotting.
For young plants, repotting once a year in the springtime is fine.
However, mature plants that have attained their full size may be perfectly happy staying in the same container for three or four years.
Pests can also cause Cast Iron Plant leaves to turn yellow.
But, again, spider mites are the main suspects.
These little sap-sucking insects suck the life out of your plant.
You’ll know you have a spider mite infestation if you see small webs on the plants’ leaves, accompanied by tiny holes in the foliage.
To confirm your spider mite diagnosis, try wiping the undersides of your plant’s leaves with a clean paper towel.
If the towel comes away yellow, you can be sure you have spider mites.
How To Prevent And Battle Spider Mites
Spider mites thrive in arid settings.
Prevent them from setting up shop with correct watering and frequent misting.
If you do find that you have a spider mite infestation, you can wash away quite a few of them by giving your plant a good shower.
You can place your plant in the shower as it’s regular watering if you wish.
This will help clean and hydrate the leaves and keep spider mites away while providing a good, deep soaking.
If you find that overhead drenching isn’t enough to eliminate spider mites, try spraying your plant with a neem oil solution immediately after watering.
Dirty Leaves Are Subject To Chlorosis
Keeping your plants’ leaves clean is important because dust build-up can also cause chlorosis.
Also, even though Cast Iron Plants are low-light plants, they need some light for photosynthesis.
If a layer of dust builds upon the leaves, it will block all light.
This will cause your plant’s leaves to turn yellow.
Wiping off the leaves occasionally and/or showering your plant will help keep the leaves clean and functioning properly.
Old Leaves Naturally Turn Yellow
Sometimes lower leaves will turn yellow and die as a matter of course.
If one or two bottom leaves turn yellow, and there is no recurrence, don’t be too concerned. Just prune them away.
Trim Away Yellow Leaves
Never allow damaged or dead leaves to stay on the plant because they may cause pests, fungus, or bacteria problems.
Any time any yellow leaves appear, for any reason, prune them off completely.
Once a leaf starts to turn yellow, it is dying.
You can’t save part of the leaf.
Just cut it all the way back to the soil.