Growing & Care for Philodendron Radiatum

Last Updated on June 9, 2022 by Admin

The Philodendron Radiatum is a split leaf philodendron with many lobes. It will grow into a good sized plant with large leaves.

The plant also likes to climb so giving it a support will not only make it grow faster and bigger and also yield larger foliage.

Its looks resemble the Philodendron Mayoi which is why some people confuse the two for one another.

The Philodendron Radiatum is native to the tropical regions of Central and South America.

How do you care for the Philodendron Radiatum? It thrives medium to bright indirect light. And it does well in low light as well. But avoid harsh direct sunlight.

The plant is used to tropical weather so warm, humid conditions are ideal. Avoid the cold and winter weather. Always check the soil before watering. Let it partially dry before you add more water.

Table of Contents

Philodendron Radiatum Plant Care

Light Requirements

The Philodendron Radiatum enjoys plenty of light. But make sure that it gets indirect or filtered light.

That’s because the plant is used to this kind of light in its native habitat.

In the jungles of Central and South America, it lives under the shade of the forest canopy. The larger plants and trees give it cover which keep it from the harshest rays of the sun.

Therefore, it has gotten accustomed to indirect, filtered, dappled or diffused light.

So, in addition to thriving in medium to bright natural sunlight, make sure that this light is filtered or indirect.

Avoid very strong light or that direct sunlight especially during the hottest times of the day and year.

If you leave it in this kind of environment, its leaves will turn yellow. In more intense exposure, the sun will scorch its leaves leaving you with burn marks.

For this reason, it is important to choose the right location for the plant.

Keep the plant at least 3 or more feet away from a south facing window. It will do well near an east facing window since the morning sun is more gentle.

In the west, it will likewise be okay with late afternoon sun.

The Philodendron Radiatum likewise does well in low light. So, you don’t necessarily need to keep it near a window.

Outdoors, place the plant in partial shade. Keep it away from full sun.

Temperature

The Philodendron Radiatum is a warm weather plant. It is native to the tropics which makes it accustomed to moderate to hot climates.

As such, it is more adaptable to this kind of weather.

Its ideal temperature is between 55 to 80 degrees Fahrenheit. And it can tolerate all the way up to 95 degrees Fahrenheit without any problems either.

However, it has very little leeway on the cold end.

That’s because there are no cold months in the tropics. And there is no snow, frost or even freezing weather there.

This is why the Philodendron Radiatum has a hard time if left in temperatures below 50 degrees Fahrenheit.

Indoors, this is not much of a problem since most homes have moderate to slightly warm temperatures.

But keep the plant away from air conditioners, cold draft and spaces where the temperature can drop significantly during night.

Another thing to watch out for is temperature fluctuations.

Sudden and large swings are not good for the plant. And it can experience stress or shock because of this.

Outdoors, you need to be more mindful of the weather.

If you live in USDA Hardiness Zones 9 to 11, then you can keep the Philodendron Radiatum outdoors all year long. It enjoys the weather there since things stays sunny and generally warm 365 days a year.

But in colder areas, be careful of the latter months of the year.

Bring the Philodendron Radiatum indoors and keep it warm in your home. Don’t leave it in the cold as it is not winter or frost hardy.

Humidity

The Philodendron Radiatum enjoys high humidity, ideally 60% and higher.

If you can keep humidity at these levels, the plant will reward you by growing larger and produces bigger leaves that are very vibrant in color.

Again, this stems from its tropical nature.

In these regions, humidity tends to stay between 60% and 75% most of the time. It does go up during rainy days. And will drop a bit during the hottest, driest days of summer.

They don’t have snow or winter in the tropics.

For the most part, the seasons are hot and sunny or rainy. That’s about it.

Fortunately, the Philodendron Radiatum plant tolerate humidity of 40% and slightly lower. So, unless you live in a desert city or somewhere with very dry air, you probably won’t need to do anything extra to accommodate the plant.

However, if you notice that the plant’s leaf edges and tips turn brown, crispy or dry, it means that you need to up the humidity.

As long as you increase air moisture around the plant, it will be fine.

You can do so by misting it a few times a week or using a pebble tray. You can also invest in a humidifier.

How Often to Water Philodendron Radiatum

The Philodendron Radiatum enjoys moist soil. As such, it likes regular watering.

However, avoid overwatering it.

If you see the soil surface soggy or wet, it means the plant is getting too much water. Therefore, cut back on watering.

Overwatering is harmful for the plant because its roots cannot tolerate sitting in water for very long periods of time.

If they do, they end up suffocating.

This is why it is important to allow the top few inches of soil to dry out between waterings.

By waiting before you add more water, it keeps the plant from having wet feet which it hates.

If you want to play it safe like I do, wait until the top 25% to 50% of the soil has completely dried. Anywhere in between this range is fine. And you don’t need to be precise.

This will keep you from overwatering the plant.

Additionally, it also reduces how often you need to water.

Besides knowing when and how often to water the Philodendron Radiatum, it is also important to understand how to water the plant.

Its likes to drink. But it hates staying wet long after that.

Therefore, the best way to water is to soak the entire root ball. Keep adding water until you see liquid trickling down from the bottom holes of the plant.

Also, water directly onto the soil. Don’t water from above where you wet all the leaves. This can increase the risk of fungal disease.

Once the soil is saturated with water, allow the plant to completely drain.

This takes anywhere from 12 to 30 minutes depending on how big the plant and pot are.

Never skip this step. It will prevent overwatering and waterlogged soil.

And it ensures that the roots don’t stay in lots of water for any length of time.

What you end up with is a well-hydrated Philodendron Radiatum that got all the drink it wanted. And the soil is moist not wet since you let it completely drain afterwards.

Philodendron Radiatum Potting Soil

The Philodendron Radiatum will grow best in well-draining soil that is high in organic matter. It will likewise do best in soil pH between 5.0 and 6.0.

The soil pH will allow the plant to efficiently absorb the nutrients from the soil.

Additionally, good drainage is very important to keep the plant away from overwatering and waterlogging.

You never want to use heavy soils since they will retain too much water.

What happens here is that when the top soil dries, the bottom stays wet. So, you fall into the misconception that it is time to water.

But in doing so, you add more water to already wet soil at the bottom.

This will eventually make the roots drown in excess liquid. And if it does not drain or recede fast enough, the roots will suffocate and die leading to root rot.

Therefore, good drainage is very important when choosing the right kind of soil for the Philodendron Radiatum.

The simplest way I’ve found to give it the perfect soil it needs is to use an Aroid Mix.

This is available online and in some nurseries.

You can also make it yourself.

Here’s a simple recipe that works well. Combine equal parts of:

Sphagnum moss
Perlite
Orchid bark
Activated charcoal
Worm castings

The moss holds some moisture while the perlite, bark and charcoal provide excellent drainage. Meanwhile, the worm castings give the soil slow-release nutrients.

If you prefer something much simpler and more minimalist, you can use a mixture of:

Peat moss
Perlite
Orchid bark

Fertilizer

Feed the Philodendron Radiatum with a high quality balanced fertilizer during its growing season.

Avoid any cheap, low quality fertilizer as these are heavy in salts.

Plants hate salts which is why many cannot survive near beaches and oceans.

The problem with these excess salts is that the more you apply fertilizer the more salt is left to build up in the soil.

After a while, these salt residue will damage the roots, which harm the plant.

Of course, you can opt not to fertilize the Philodendron Radiatum. But it will grow slower, won’t get as big and won’t produce leaves that are as large as it normally does.

Therefore, it is a good idea to feed the plant.

Once a month feeding during the warmer months is all it needs. Dilute the dose by 50% if the plant is in a pot. Use full strength if the plant is in the ground in your garden.

Besides liquid fertilizer, you can also opt to go with slow-release fertilizer.

These come in pellet form. But you’ll only need to fertilize 2 or 3 times a year.

Pruning

The Philodendron Radiatum is a good sized plant given the proper care and living conditions.

It can grow to between 8 to 10 feet tall. Its leaves will likewise reach 3 feet in length and potentially 2 feet wide.

The most attractive parts of its foliage are a large lobes.

And you’ll see anywhere from 8 to 16 lobes in all when you total both sides of a leaf.

It is also worth mentioning that the Philodendron Radiatum also has a variegated version if you prefer color variation to the solid green leaves.

The variegated Philodendron Radiatum has cream and yellow markings that go with its green foliage.

In addition to its potential size, the Philodendron Radiatum is also a fast growing when give the right care.

This can be both good or bad depending on how much space you can allocate for the plant.

Faster growth means larger plant with more impressive leaves. But it can be a problem if you’re short on space.

Therefore, if the latter is the case, pruning comes into play.

You can prune the plant to control it size and shape. Doing so will make the plant bushier as well.

Finally, the Philodendron Radiatum is a climber.

In its native habitat, the plant is an epiphyte in the forests of Central and South America.

So, it will grow faster and bigger if you give it a totem or a support to go up on. The leaves will also develop into larger sizes with more lobes.

How to Propagate Philodendron Radiatum

Philodendron Radiatum propagation is commonly done using stem cuttings, air layering or division.

All of these methods work very well. But they require different levels of work. And the resulting new plant will end up at different stages once you’re done with propagation.

That said, stem cuttings are the simplest and most practical way of propagating this plant.

This is why it is the most popular method used by most home gardeners.

Here’s how to propagate the Philodendron Radiatum from stem cuttings.

Choose healthy stem to propagate. You want cuttings of 4-6 inches long with at least 1-2 nodes and several leaves on it.
Take a sterile pair of scissors or pruning shears, then cut just below a node.
Allow the cut end to dry and callous. This usually takes a few hours. In the meantime, prepare a pot and fill it with well-draining potting mix.
Once calloused, apply rooting hormone to the cut end of the stem. Skip this step if you don’t have any.
Plant the cutting in the soil mix. Remove any lower leaves that end up in the soil.
Place the pot in bright, indirect light with good humidity.

In about 4-6 weeks new roots will have developed and are starting to get established into the soil.

Of course, you can also propagate the Philodendron Radiatum in water.

With water propagation, place the cutting into a jar filled with water. You can use any jar you want. Ideally, it is transparent so you can see the roots as they grow.

In about 3-4 weeks the roots will grow enough so you have quite a few of them.

Wait until the roots reach about 1-2 inches or longer. You can then transfer them to a pot with well-draining soil mix.

How to Repot or Transplant Philodendron Radiatum

The Philodendron Radiatum will need repotting every 2 to 3 years. It has a healthy, well-established root system. You’ll also see quite a few thick, woody air roots growing above the soil.

The only time you need to repot the plant is when it outgrows its container.

Here, you’ll see roots sneaking out from the drainage holes at the bottom of the container. Or, you’ll see roots popping up from the surface of the soil.

Both are signs that the plant needs more room to grow.

The best time to repot is during spring to early summer.

When doing so, move the plant to a larger container that’s about 2-3 inches bigger than its current one.

As the plant gets bigger, avoid trying to carry it. Instead, tip in on its side the slide out the root ball. This helps you avoid any possible back injury from lifting a big or heavy object.

Replace the soil with fresh, well-draining soil as well.

Is It Toxic/Poisonous to Humans, Cats & Dogs

Keep the Philodendron Radiatum away from young children, cats and dogs. It is toxic when ingested.

And this affects both people and animals.

Therefore, you don’t want any accidental eating or chewing of the leaves what may cause vomiting, swelling, shortness of breath, inflammation and many other side effects.

Philodendron Radiatum Problems & Troubleshooting

Pests

Mealybugs, aphids, thrips and spider mites are common pests that will bother the Philodendron Radiatum.

While they won’t come around too often, you do need to regularly inspect the plant.

This way, if any of them attack the plant, you’re able to spot them early.

The reason is that these pests will multiply very quickly.

And it only takes days before their eggs hatch. What’s worse is that one adult will lay several eggs. This is compounded by their short lifespan.

So, you’ll see a lot of turnover from one generation to another, which increases their number fairly quickly.

The earlier you spot them and get rid of them, the better.

Diseases

Root rot is the biggest thing to watch out for. And it is caused by overwatering.

Therefore, avoid overwatering.

Watering too often, using heavy soils or a pot with insufficient drainage will increase your risk of this.

So, make sure to be mindful of when you water and how you water.

If you seed any signs of root rot, repot the plant after pruning the rotten roots.