The Philodendron Stenolobum is also known as the Thaumatophyllum Stenolobum. It used to be classified as a philodendron plant but in 2018 has been reclassified under the Thaumatophyllum genus.
Nevertheless, you’ll likely see shops still selling the plant as Philodendron Stenolobum since this is what most gardeners know it as.
The Philodendron Stenolobum is a beautiful hybrid that looks like it comes out of the TV show Game of Thrones.
This is especially true when the leaves get long and narrow and start shooting out in different directions.
It is a native of South America which is why it enjoys tropical weather.
How do you care for Philodendron Stenolobum? Keep the plant in bright, indirect light indoors and partial shade outdoors. Moderate to warm temperature and good humidity is ideal.
Be careful about overwatering and waterlogging since it is prone to root rot. Let the soil dry slightly between watering and use well-draining soil.
Philodendron Stenolobum Plant Care
Thaumatophyllum Stenolobum Light Requirements
The Philodendron Stenolobum will grow best in medium to bright indirect light. This will allow it to get big, produce lots of large leaves and maintain its deep green foliage color.
The plant can likewise tolerate low light.
However, I’ve noticed that it won’t be as impressive as if you kept it in a well-lit location.
The reason why the Philodendron Stenolobum enjoys plenty of light is that it lives in the tropical jungles of South America.
But its sizes keeps it under the canopy of leaves and branches of the larger trees.
Therefore, it is important to be wary of excess light.
The plant can tolerate short periods of direct sunlight. Beyond this, it will experience leaf discoloration and even sunburn.
This means you want to avoid the sun’s rays during the hottest times of the day which occurs between 10:30 a.m. and 3:30 a.m.
Inside your home, the sun will typically come from the south facing window during the earlier to mid part of the day and the west facing window in the afternoons.
As such, take note of these locations since you’ll either want to distance the plant from the window or use some kind of filter to block out some of the sunlight.
Thaumatophyllum Stenolobum Temperature
The Philodendron Stenolobum will be healthiest and happies when temperature stays between 65 and 80 degrees Fahrenheit.
Note that it can tolerate conditions all the way down to about 55 degrees Fahrenheit.
But avoid leaving it anywhere, indoors or outdoors, where the temperature drops below this level.
It is not cold hardy and it cannot tolerate low temperatures. That’s because its natural habitat are the tropics where the sun shines 365 days a year including November through March.
As such, the Philodendron Stenolobum does not see winter, nor does it experience freezing temperatures.
For this reason, it is important to keep the plant indoors during the winter.
Still, even indoors you want to keep it warm during this time of the year. The Philodendron Stenolobum does not like temperature fluctuations so keep it away from fireplaces, heaters, radiators and other similar appliances.
During the summer, avoid the air conditioner as well.
Note that the plant thrives outdoors in USDA Hardiness Zones 9 to 11. That’s because these locations, which are the southern coastal states, have warm weather all year round.
States like Florida, Texas and California let the plant live outdoors even through the latter part of the year without any problems.
Thaumatophyllum Stenolobum Humidity
The Thaumatophyllum Stenolobum enjoys high humidity, ideally between 65% to 80%. That’s because the plant is used to the tropical environment, which is consistently humid.
That said, the Thaumatophyllum Stenolobum does not mind average room humidity as long as the air does not get too dry.
This means you want to avoid indoor humidity that’s in the low 30s or high 20s.
While it can withstand this when well-hydrated, you’ll need to stay on top of its watering to maintain this balance.
Otherwise, once the moisture level starts lacking, you’ll see its leaf tips turn brown. Along with those are the edges of the leaves.
And the longer the humidity stays low, the more leaves will turn brown.
As such, it is important to keep an eye out for this symptom. And if it does appear, make sure to take action as the brown leaves will not turn green again.
Instead, you’ll need to remove them and wait for the plant to grow new ones.
Here are a few ways to increase humidity around the plant.
Use a humidifier, set up a pebble tray or humidity, group it with other plants, move it to the bathroom and mist it regularly.
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How Often to Water Philodendron Stenolobum
The Thaumatophyllum Stenolobum enjoys moist soil. However, you want to be careful with overwatering the plant and leaving it wet soil.
This is the most dangerous environment you can put it in as it is prone to root rot.
As such, avoid watering too often.
Instead, allow the soil to dry partially before adding more water.
The best way to water the Thaumatophyllum Stenolobum comes in 2 steps.
The first is knowing when to water the plant.
Feel the soil.
This is the most important thing to do. You only need to feel to surface every half week or weekly. If it feels moist, don’t water.
If the surface of the soil feels dry, stick your finger into the potting mix about 2-3 inches deep. Then take it out.
If your fingertip feels dry and only soil dust is on your finger, then it is time to water. But, if your finger has some soil sticking to it or feeling of wetness, wait a few more days then test the soil again.
Never water the plant until the top few inches have completely dried out.
The second thing to know is how to water the plant.
When watering, never water over the plant to wet the leaves. The only time you do this is to give the plant a shower to clean the leaves or to help increase humidity.
If you wet the leaves, make sure to pat them dry after to avoid fungal infections from developing.
Instead, watering directly onto the soil using a garden hose or a long-necked watering can.
Keep letting water go until the liquid starts trickling from under the pot’s drainage holes, then stop. After that allow the soil to completely drain before putting the plant back to its spot.
Waiting until the soil has dried allows you to prevent overwatering. And by soaking the plant you give the roots all the drink they need.
But again, make sure to let excess moisture drain after to avoid waterlogging and overwatering.
Philodendron Stenolobum Potting Soil
The other part of avoiding overwatering is using the right kind of soil.
For the Philodendron Stenolobum, that means a porous, well-draining soil that’s rich in organic matter. It also enjoys soil pH of 5.1 to 6.5, which will let it efficiently absorb nutrients from the soil.
From the watering section, you already know why good soil drainage is important.
If you get heavy, dense or compacted soil, the excess moisture you pour when you water the plant will not drain.
As such, this leaves the roots sitting in too much water which results in root rot sooner than later.
Thus, well-draining soil allows the excess liquid to quickly drain out to let the soil stay moist.
An easy way to get this kind of soil is to use an Aroid mix.
You can pick up a bag from your garden center or an online plant shop.
Similarly, you can make your own DIY potting mix for the Philodendron Stenolobum as well. All you need to do is mix peat, perlite and orchid bark.
The peat will retain some moisture to keep the roots hydrated. On the other hand, the perlite and orchid bark allow for drainage.
The bark is also chunky so oxygen can easily reach the roots.
Finally, don’t forget to make sure that the pot you use has drainage holes as well. This will let any liquid that drains from the soil to escape out of the pot.
Together the right soil and pot will prevent waterlogging.
The Philodendron Stenolobum appreciates fertilizer during its growing season. This will help it grow faster and produce more leaves.
As such, make sure to feed the plant during spring and summer.
It does not need fertilizing in the fall and winter as the weather gets cold. This causes the plant’s growth to slow down.
You can use an all-purpose fertilizer or a balanced formula. Both will work well.
Don’t forget to dilute the application by half if your plant is kept indoors in a pot. It won’t need a strong concentration.
If the plant is growing in the garden outside, then use the full dose on the product label.
One a month feeding during spring and summer is ideal. You can bring that up to once every 2 weeks. But avoid being too aggressive with plant food.
Too much fertilizer, applying too often or applying when the plant is not actively growing can lead to over fertilizing which is harmful for the plant.
Thaumatophyllum Stenolobum Pruning
The Thaumatophyllum Stenolobum will grow into a large plant that can easily cover anywhere between 1 to 3 people behind.
The biggest I’ve seen was about 10 to 12 feet tall and amazingly full that it looked a large bush that 3 people could hind behind and you would not see one trace of the people.
That said, in most cases, the plant will not have as many leaves.
Nevertheless, a sparse Thaumatophyllum Stenolobum can have about 8 leaves while a thicker one about 25 or so.
Each leaf is amazing getting to about 2 or 3 feet long.
Their jagged looks make them look like something that belonged to Game of Thrones.
As such, pruning is needed depending on how you want the plant to look.
If you’re keeping it indoors, you’ll definitely need to trim it regularly to keep its size from getting too big. However, I prefer leaving it in the patio in partial shade.
This gives it a lot of room to grow which lets you see the plant in all its glory.
When you let it get big and bushy, it becomes very impressive.
How to Propagate Philodendron Stenolobum
Philodendron Stenolobum propagation is fairly easy as the plant responds well to stem cuttings. This lets you grow new plants at home from free.
As a bonus, you can propagate the plant in water or in soil.
Here’s how to propagate the Philodendron Stenolobum from stem cuttings.
- Take a healthy cutting that’s between 4 to 7 inches long. Make sure each cutting has at least one node and a few leaves on it.
- Using a sterile pair of shears, cut the stem just below a node.
- Next prepare a well-draining potting mix. You can use the recipe above. And fill a pot with it.
- If you have rooting hormone, apply it on the cut end of the stem. Don’t worry if you don’t have it as the plant will grow fine even without rooting hormone.
- Plant the cutting in the soil with the nodes buried under.
- Water the soil and keep it moist. Also, place the plant in a well-lit location with no direct sunlight.
It takes about 4 weeks for the cuttings to start getting established in the soil.
Alternatively, you can likewise place the cutting in water instead of soil.
If you do this makes sure to submerge the nodes in the liquid. Once the roots grow to about 2 inches or longer, you can transfer the cuttings into a pot with soil.
How to Repot or Transplant Philodendron Stenolobum
The Philodendron Stenolobum will eventually end up in a larger pot. And you’ll need to repot it over 2 years on average.
Note that you don’t want to jump pot sizes when you repot.
I’ve seen some home gardeners do this as they hope to reduce the work they need to do. This for me is a no-no as overpotting increases the risk of overwatering.
That’s because overly large spot means excess soil volume relative to the size of the root system. So, when you water, the roots end up in a lot of extra moisture which takes much longer to dry.
This increases the risk of overwatering.
That said, don’t repot unless needed also. The plant does not like being moved so avoid it if not necessary.
The only time it needs repotting is when it gets root bound.
And you can check this by taking a look at the bottom of the pot. If the roots are coming out of the holes, then it is time to move the plant to a larger container.
The best time to do this is during spring to early summer.
Is It Toxic/Poisonous to Humans, Cats & Dogs
Yes, the plant is toxic. It contains calcium oxalate crystals which are toxic to humans and animals.
Note that the plant only becomes toxic when ingested as this is when the crystals get activated. Therefore, try to keep young children, dogs and cats away from the plant.
This avoid any accidental consumption of the leaves.
Philodendron Stenolobum Problems & Troubleshooting
The Philodendron Stenolobum has good resistance to pests. Therefore, there’s a high likelihood that you’ll never need to deal with them if you keep the plant healthy and its leaves clean.
That said, there’s always a chance of pests for any houseplant.
This is especially true when it is weak, stressed or sick.
The most common pests that will attach the Philodendron Stenolobum include spider mites, aphids and mealybugs.
These are sap suckers that will rob the plant of its valuable sap. As a result, you get yellow leaves, slow growth and a weaker plant especially as the infestation grows.
If this happens, use insecticidal soap or neem oil to get rid of the pests.
Root rot is the most dangerous thing to want to watch out. However, it is not the only thing that can kill your plant.
Other diseases including leaf spot and blight can likewise do the same depending on what kind of infection hits the plant.
Therefore, is important to be careful with excess water considering the plant already likes humidity.
Both bacterial and fungal infections can occur, so, always be on the lookout for any abnormal development on the leaves and stems.