Philodendron Radiatum is famous for its leaves that instantly give a tropical look.
Sometimes called Split Leaf Climber, you can grow this beauty inside and outside on your summer gardens or patio by following our plant care guide.
Table of Contents
Philodendron Radiatum Care
To care for a Philodendron Radiatum, use well-draining soil with a pH of 5.1-6 and keep it in bright, filtered light. Water when the top inch of soil is dry. Maintain indoor temperatures between 55-80°F and provide humidity above 60%.
Soil
You have to grow the Philodendron Radiatum plant in well-draining soil that has high organic matter and nutrients. You might have to alter the regular potting soil to ensure it holds some moisture. Add a burlap or sphagnum moss post to your pot to help the plant climb upwards.
Avoid potting this plant in a sandy mixture. And keep the pH of 5.1 to 6 because this species prefers acidic soil mixture. My research about this species proved that it’s a rainforest plant that likes growing in a mixture of perlite and peat moss that has been adjusted by adding orchid bark for good drainage.
Outside, you can easily grow this plant if you are situated in USDA hardiness zones 9b-11. I would suggest growing this plant outdoors in areas only with mild climates and no freezing temperatures.
Watering
Philodendron Radiatum has average water needs, but it likes to be watered regularly. Make sure you do not overwater it. Let the soil dry out before you add any water again to avoid overwatering or root rot.
Light
The Philodendron Radiatum likes filtered sunlight. Therefore, 70-85% sun is great for your indoor plant. Direct sun harms the foliage, so I recommend keeping your plant a few feet away from a window. Surprisingly, this plant will do well under low light conditions as well.
But if you want to keep your indoor planter near a window, ensure you have installed sheer curtains or blinds to filter the sunlight.
This is important because this plant needs to be protected from harsh afternoon light and heat.
Outdoors, on the patio, you have to use shade cloth or keep it in a shady location with minimum direct sunlight. Never keep your planters with Radiatum plants outside in extremely sunny or windy areas. Keeping in a very lit area will definitely result in leaf burns.
Temperature
The Philodendron Radiatum will thrive at indoor temperatures of 55 to 80 degrees Fahrenheit (12.7 to 26.7 degrees Celsius).
In cold months, you should bring the outdoor Philodendron Radiatum inside even if there is no risk of frost because this plant is not winter hardy.
This species never appreciates extreme temperatures, neither freezing cold nor very hot temperatures. Indoors, try to maintain a constant temperature that falls within the desired temperature range.
Humidity
The more humidity you provide, the larger your Philodendron Radiatum will grow with bigger, lobbed leaves. Above 60% humidity is recommended for this plant.
Fertilizer
I use a slow release fertilizer for this Philodendron plant. You can apply it tri-annually to help your plant have better and more robust growth. This plant will grow even with no fertilizer, but remember, unfertilized houseplants tend to grow slowly. This might be disappointing for some of us.
This plant likes feeding on fertilizers that are rich in magnesium. I feed mine with a 15-5-10 houseplant fertilizer. Stay away from cheap fertilizer; the heavy slats in them will damage the roots, killing your beloved plant.
Repotting
This is a healthy species with a well-established root system, so it requires very less repotting. This plant produces thick air roots that might overgrow the pot. You can repot it after 2-3 years.
Pruning
If your plant has been growing aggressively, you can trim some stem growth from the top of the plant to control and manage the size. This will also force the plant to grow more leaves at the lower parts to achieve a bushier appearance.
Some Philodendron species cause irritation and skin allergies, so I would suggest wearing protective gloves while handling or pruning your plant.
Propagation
Two propagation methods are discussed for Philodendron Radiatum; air-layering and water propagation.
Air Layering
Air layering allows us to propagate our plant even before taking any cuttings. Therefore it is one of the safest and interesting methods for propagation. Keep reading to know all the necessary steps:
- Locate a healthy stem on Philodendron Radiatum, wrap the sphagnum moss around the node, and the vertical support (if any). Wrapping around the support will secure the moss better.
- I would recommend soaking the sphagnum moss in water for 1 -2 hours before you start the process. This moisture will create a humid environment that encourages better growth.
- Use clear plastic sheets so that you can see the moss. Avoid wrapping any leaves because they will eventually rot.
- You have to keep a small hole on top while wrapping for airflow.
- This approach for propagation is safe because even if the node fails to form any roots, you have not taken the cutting, so you did not lose anything.
- Don’t forget to spray the sphagnum moss every two days to keep it moist. The node will start rooting in 2-3 weeks.
- Open the wrapping to remove the moss around the roots.
- Now take cutting by making an angled cut just below the node. The final cutting should be a few inches long with at least two leaves on it.
- Finally, place the cutting in a transparent plastic cup and replace the sphagnum moss.
- Follow the care instructions mentioned previously in this article to care for the Philodendron Radiatum.
Water Propagation
- After choosing a mature and healthy stem on Philodendron Radiatum, take stems cuttings that are 4-6 inches long in the growing season. Make the cut above an existing leaf joint.
- The location of the cut is important; make sure it is ¼” below the node.
- Pinch the lower leaves from the cutting to have some bare leaf nodes. Now let the cutting dry for 24 hours. And later, dip the bare ends in rooting hormone powder.
- Rooting hormones help the cutting to root faster.
- Fill a clear jar with water leaving at least 1-inch space at the top. I would suggest using filtered water instead of tap water.
- For tap water, let it sit overnight; this will dissipate chlorine and other fluorides. Using room temperature water is also important because using too cold or too hot water can shock the cutting.
- Place the leafless nodes in water to ensure that the remaining leaves do not touch the water.
- Refresh the water after two days using filtered, room-temperature water.
- Place the cutting in bright sunlight to help it root. Avoid direct sun because it can encourage algae growth in water.
- The cutting will start rooting in 3-4 weeks. Once the roots are a few inches in size, you can transfer the cutting to the soil.
- Remember, the longer the cutting stays in the water, the more difficult it becomes for the plant to acclimate to the new environment.
- Follow the usual care instructions mentioned above to help it grow.
- This is my favorite method because I can see the root development for my cutting. But you have to be patient with water propagation because it takes longer compared to soil propagation.
Blooms
This Philodendron species never blooms, but it produces inflorescences known as spathe and spadix. Both of these are green with a tinge of red and a dark purple center. It is mostly grown for its foliage that can adorn any area by adding a tropical touch.
Growth
This Philodendron species has a medium growth rate. For this reason, it mostly never takes over any neighboring plant. But this plant likes to climb upwards as it grows on trees in nature; therefore, providing vertical support will greatly benefit.
The selling point for this plant is the giant leaves that can get up to 3 feet long and 2 feet wide. These vigorous, green leaves will vary in shape as the plant matures.
A young plant has heart-shaped, small leaves, whereas a mature plant has deeply incised leaves with scalloped margins that grow on long petioles. Each leaf has 5-10 lobes on each side of the blade. The leaves are smooth but textured.
The growth rate for every houseplant varies depending on the water, light, temperature, and plant food provided. Pay attention to your plant’s individual needs to ace the plant care. This plant has a mature size of 8 to 10 feet under optimum conditions; this plant will produce one new leaf every month.
There is a variegated version of Philodendron Radiatum; the leaf shape is similar to the original one, but the color varies in shades of yellow, green, and cream.
Common Problems for Philodendron Radiatum
Mealybugs
Mealybugs are the most common houseplant pest for Philodendrons.
They feed on plants and secrete a waxy substance known as honeydew.
They are identified by a white powdery and cottony substance or dust visible on different leaves.
The bodies of these insects are oval and covered with a sticky substance. The male bugs resemble aphids in appearance.
Another symptom of mealy bugs is sooty mold on the plant surface, combined with stunted growth and early leaf fall.
The female mealybugs cannot fly, so these bugs mostly spread via a newly bought plant or potting soil. Buy your houseplants from trustworthy sources and inspect the newly bought plant. It is best to quarantine the new plants for about 14 days.
For treatment, disinfect your plant using a good quality insecticide. You can make your own spray using water, bio-friendly soap, and oil.
Neem oil is another remedy against mealybugs infection, but you must reapply until all the mealybugs are gone. If the plant has heavy infestations, dispose of the entire plant.
Thrips
Thrips, also known as thunderflies, are tiny insects with slender bodies and long wings. They will suck the juices from the new leaves on Philodendron Radiatum. The plant will have discoloration and distorted growth.
They attack plants in groups and are black, brown, cream, or yellow-colored.
If you want to check your plant for thrips, gently disturb the stems, and these pests will start flying over the plant(if present). The nymphs are paler in color compared to adult thrips.
The main symptoms of infection are:
- Mottled leaves.
- Silvery-white discoloration on the leaf surface.
- Distorted leaf tips and flower buds.
- Failed blooms
Thrips can be avoided by practicing good housekeeping. Inspect the leaf and stem joints regularly because these are the main locations where the females lay eggs.
Avoid using green mulch because that attracts the thrips.
For small infections, yellow sticky traps are the easiest and cheapest solution. They can also be used to monitor the presence of any pests.
Take your infected plant outside and gently spray it with water to remove the eggs and nymphs.
If you want to use a chemical spray, check the label carefully because most thrips develop resistance against chemical sprays. You should never apply any chemicals for minor infections.
Aphids
Aphids are the next most common pest for houseplants after mealybugs. They belong to the Aphidoidea family, and there are more than 4000 species. They are soft-bodied insects with a complex life cycle.
These pests feed on cells in plant leaves and deprive the plant of vital nutrients. This reduces the green area on the plant, leading to discoloration. They feed on new growth on the Philodendron Radiatum in clusters. The main symptoms are:
- A decline in plant health.
- Leaf yellowing.
- Distorted, abnormal growth.
They also secrete the sticky honeydew that will attract ants and sooty mold. To prevent the spread of aphids, clean plant debris and weeds from the soil surface regularly.
Treat your infected Philodendron with a water jet to dislodge the insects from the leaves and stems. Later, spray your plant with a soapy mixture of water; make sure you rinse the plant with clean water to get rid of the remaining soap. Let the plant dry out, and remove the aphids by hand using a damp cloth.
You can also use a cloth dipped in rubbing alcohol to target the hidden areas like the undersides of leaves, stem and leaf joints, etc.
Tips for Growing Philodendron Radiatum
- This plant will flourish on a patio in summer, but it is best to bring it inside during cold, frosty winters.
- Install a shade cloth before you move this plant to your outdoor garden or patio.
- To avoid transplant stress, I recommend keeping the plant in the new environment for about one week for a few hours every day. Then, you can permanently move the plant to the new location.
- Established plants might tolerate an hour or two of direct sun, but young plants have to be protected from direct sun.
Frequently Asked Questions about Philodendron Radiatum
Is the Philodendron Radiatum toxic like other species?
There is no specific mention of any health hazards of this plant. However, most species from this plant family contain calcium oxalate, which is proven to be toxic. So I suggest keeping this plant away from children or pets in your house.
Will the Philodendron Radiatum purify the air?
Like other Philodendrons, this one also purifies and removes harmful toxins from indoor air in your house, office, or lobby.
How can I encourage huge leaf growth on my Philodendron Radiatum?
Add a totem or any other vertical support to help your plant produce huge green leaves.
Why is my plant not producing any new leaves?
This plant can take several weeks before you notice any new growth. Do not get discouraged and continue the usual care. Make sure you provide the necessary light and temperature for your plant.
Can I keep this plant in a lobby area with little to no sunlight?
This hard to kill Philodendron plant can survive anywhere, even at a place like a dark lobby where no waters them, and they hardly receive any sunlight.
When should I water my Philodendron Radiatum?
When at least 1/3 of the potting soil has dried out, your plant will benefit from a drink of water.
Conclusion
This tender perennial is a beautiful addition to your houseplant garden. This plant is considered as an easy-going plant compared to the exotic foliage it produces. You definitely need one if you like to collect plants with huge leaves. This species hardly sheds any leaves and, if treated well, keeps growing for several years.