Philodendron Rojo Congo - [Red Philodendron Care ]

 

Philodendrons with red leaves, including Philodendron Congo Rojo, Black Cardinal, Imperial Red, and Congo Red, are all magnificent. It's little wonder that so many people are captivated by their striking dark-reddish leaves, and caring for red philodendrons is so simple that even inexperienced plant parents will feel confident in their abilities!

This page will cover everything you need to know to successfully cultivate the philodendrons I'm referring to as belonging to the "red" category, including comprehensive background information.

WHAT WE'RE GOING TO COVER IS AS FOLLOWS:

Red Philodendron Cultivar Background

Red Philodendron Cultivar Background

Let's first learn a little about the red philodendron's native habitat, how it came to be, and why it looks the way it does, before moving on to how to care for it. 

Red philodendrons' historical context gives a foundation for their care, making sense of their growth requirements. 

Philodendron Native Habitat

Following the genus Anthurium, philodendrons are the second-largest genus in the tropical family Araceae. They are indigenous to the West Indies and the tropical Americas. Although they are a big and diversified genus, they can be found in a variety of settings and elevations, with the majority occurring in humid tropical woods. 

Philodendron Taxonomy - which one is which?

In the middle of the 1990s, Philodendron 'Rojo Congo' was created by cross-pollinating a female Philodendron 'Imperial Red' with an unidentified philodendron. (Learn more about the history of "Congo Rojo" from this patent.) 

It might be confused quickly because there are numerous cultivars of philodendrons with reddish foliage. 

The label on the one I purchased reads Philodendron 'Congo Red', and I made the purchase around a year and a half ago. I wondered, after a little study, "Is this even a thing?" 

'Congo Red' Philodendron I have. Although the foliage is somewhat brownish, the camera manages to capture the green.

I was keeping an eye out for Philodendron Imperial Red, Congo Rojo, and Black Cardinal. Not so much for Congo Red. Commercial growers occasionally err on the side of labeling (it's near enough!). 'Black Cardinal' is a good example.

In comparison to Rojo Congo and the other red varieties, Black Cardinal distinguishes itself by having larger, rounder leaves that are darker in color. (This video demonstrates the difference.) In light of this, take a close look at the foliage while observing what is occasionally referred to as the "Black Cardinal" surrounding you.

Although I can't discover a single scholarly citation about a "Congo Red" cultivar, my "Congo Red" may be a hybrid-between-hybrids.  If anyone can declare with certainty,

Tips for telling red philodendrons apart:

The foliage of Imperial Reds should be somewhat green, whilst the foliage and petioles of Congo Rojos should be more crimson. (I think my Congo Red is somewhere in the middle.)

In contrast to Imperial Red and Congo Rojo, "Black Cardinal" features darker, deeper-brown foliage with rounder, bigger leaves, and larger total plant size. 

When you add such hazy comparisons to environmental variation, it might occasionally seem as obvious as mud. 

In varied degrees, all varieties of red philodendrons have crimson petioles, which join the leaf to the stem. 

This Red Cherry cultivar appears to offer lovely contrast between the deep red and green foliage. 

Why Are Red Philodendrons Red?

At least we can agree that their foliage is all crimson. Then why is it red?

Anthocyanin is found in red foliage, whether it is seasonal like a deciduous maple leaf, or evergreen like a tropical plant. Plants, flowers, and fruit have bright colors ranging from pink to red, purple, and blue thanks to compounds called anthocyanins.

Anthocyanin plays a significant role in giving things a red tint, even if it's not the sole one. The production of anthocyanins requires a lot of energy from the plant. Why do they do it, then? 

Anthocyanin can perform a variety of functions for non-deciduous plants, such as red philodendrons, including (but not limited to) responding to environmental stressors and attracting and repelling different animal and insect species. 

In fact, leaves with high levels of both chlorophyll and anthocyanin often have a dark or even black color, resembling dead foliage or acting as a camouflage against the soil and leaf litter on the forest floor (way to go, Black Cardinal!). To nonmammalian folivores (plant-eating insects, reptiles, etc.), which lack red light receptors, even vivid crimson or scarlet leaves can appear dark.  PMC

In contrast to the red varieties, this wild philodendron in El Yunque Tropical Rain Forest has more typical green foliage. 

Rojo Philodendron Form & Habit

Philodendrons typically grow as vines. In the rainforest, they employ the tactic of climbing a tree to gain access to more light. But in other species and cultivars, the leaves are grouped so closely together that the stem resembles a basal rosette arrangement of leaves until older leaves ultimately fall off the bottom, revealing a stem. 

Since they don't need support like many other philodendrons and tropical climbers, these philodendrons are known as self-heading philodendrons. Botanists and horticulturists further classify a subgroup of these self-headers as arborescent because their foliage is rigid enough to support the plant upright, much like a tree (arborescent refers to a tree-like quality). 

The function of supports in nature for the growth of climber plants and a DIY trellis for potted plants are related posts.

In contrast to a self-heading philodendron, this wild philodendron in Puerto Rico's El Yunque Tropical Rain Forest has a more typical vining habit. Greenhouse Studio, the image

Due to their compact basal leaf arrangement, red cultivar philodendrons are self-heading philodendrons, which means they don't require support.

Genetics + Breeding + Propagation = A Red Philodendron Winner

A compact basal form even greater than what a self-heading philodendron produces is a key characteristic breeder were selecting for when breeding "Rojo Congo," in addition to the lovely extra-red leaf. 

Through tissue culture propagation, the philodendron form has been enhanced even further. 

Plants are cloned through the technique of tissue culture using vegetative tissue—not reproductive tissue like seeds. Plant tissue, cells, or organs are grown on nutrient cultures in sterile environments, typically a petri dish or test tube. 

When a plant is propagated vegetatively (which also includes regular cuttings), it will grow into a clone of its parent plant. While seeds share their parents' genetic makeup, they are unquestionably not clones; rather, they are the reproductive equivalent of children. 

The key finding here is that tissue culture propagation encourages more basal branches per plant than non-tissue cultured self-heading philodendrons, which results in a more compact plant. (U of Florida) 

They are a compact, lovely plant as opposed to a more rangy philodendron like the one shown growing naturally in Puerto Rico because of their tightly packed leaf groups. 

In other words, these red philodendrons are more successful commercially than they would be if they had the same red leaves on extended, rangy stems due to tissue culture and the self-heading characteristic, which together produce compact plants. 

[Sidebar: Although it may seem unusual, I discovered something similar while researching fiddle leaf figs. The propagation approach affects growth behavior. Fiddle Leaf Figs grown from air layers are not as stable as those grown from conventional cuttings or tissue culture. They don't stand as strongly as FLFs spread using other methods since their roots don't develop to be as stabilizing. The larger branches that are employed for air layering probably don't assist either.]

Red Philodendron Care

Light

Philodendrons favor direct, strong light. This makes sense once you realize that they are native to rainforests. 

I discovered that the hard way. My workspace has a whole wall of south-facing windows where my Red Congo dwells. Without a glass roof, it is as near to a greenhouse as one can go. 

Instead of being above in the autumn and winter, the sun shines in at an angle. This implies that during such seasons, I receive a lot more direct sunlight. 

Last year, I kept my Red Congo, Monstera, and Hoya on a bench just beneath the windows. Let's just say that when autumn and winter came around, I quickly burned the leaves off of it. It still has the scars from when I realized it too late, even a year afterward. 

I'm aware that most people are not bothered by excessive light. The important points are as follows:

Indirect lighting will make your red philodendron happy. You don't require a lot of sun. 

If you do have powerful lighting, make sure not to expose it to sunlight for longer than a half-hour per day. 

The leaves will turn more green than crimson if there is too much shade.   

My Congo Red suffered from severe leaf burn as a result of being kept next to a window during the autumn and winter. 

Temperature & Humidity

Philodendrons prefer a range of 70 to 90 degrees Fahrenheit. When temperatures regularly exceed 95°F or go below 65°F, plant quality, and growth rates start to suffer. Both scenarios are unlikely if you cultivate them as indoor plants. 

60 to 100 percent relative humidity is ideal for philodendrons. These are plants that grow in rainforests. Make sure they aren't kept near a heating vent so they don't dry out. 

Watering Philodendrons

Since philodendrons are native to tropical rainforests, plants enjoy humidity but don't always require a lot of water. Although those who enjoy humidity may need a lot of water, this is actually not the case. 

I sometimes let mine dry out a lot between waterings, which is far from ideal and hurts my small "Red Congo" plant. I water the majority of my tropical plants in this way.  

Pick up the pot to check the water level; weight is a far better indicator of plant hydration than poking your finger into the top few inches.

If in doubt, avoid watering. Overwatering kills more plants than underwatering. 

Repotting Red Philodendrons

What size planter to use when repotting any plant, philodendron or not, is one of the most often asked questions. Here is one tactic: 

When I worked as an intern in a botanical conservatory, the aim was to repot the plant so that it wouldn't require a transplant for at least two years. This necessitates estimation, which is difficult.

To size up approximately 1-2 inches larger than its existing pot, or 2-3 inches for larger pots, is a more specific guideline. Likewise a flawed approach, but still useful. 

My Congo Red is quite active, at least according to my experience so far. The majority of the time, it is turning over a new leaf. Though it does dry out rapidly, I haven't repotted it in the year and a half since I purchased it, and it's doing just great in its original 6" pot. 

Thus, when I report, it will value the extra area; however, if you're low on space, it can also be grown in a smaller container.  

Last but not least, keep in mind that Black Cardinal is a larger plant than the other reds, therefore it would require a little more space for growing.

Design Tip: Their striking, dark foliage looks wonderful in a pot that is dark or has a strong, contrasting color. I primarily keep dark plants inside pots with a deeper color. 

(The pottery 3-pack painted in metallic brass is in my cart. Additionally, one of the dark green kitchens that are currently very popular would look fantastic with the deep peacock green one.)

Soil

You must be knowledgeable about philodendron soil mix if you are repotting.  

Philodendron soil media should be well-aerated and capable of holding moisture. The best soil is one with a peat foundation and some perlite. For good reason, this is a staple fare for the majority of indoor potting mixtures. The best solutions are frequently the simplest. 

A straightforward, efficient ratio would be 2/3 peat to 1/3 perlite. Though many other, more complex recipes might also be effective. 

Sphagnum peat, vermiculite, perlite, and even pine bark are possible alternatives.  

If you're measuring pH fancy, it should be between 6.0 and 6.5.

Recipe for philodendron soil

1/3 peat-based media

33% perlite 

If the huge plant in the small pot causes you to worry that it will dry up too quickly,

Under no circumstances should you place rocks or gravel in the bottom of your pot. 

Inquiring as to why? Visit Why Pot Shape & Size Matters: How to Choose the Right Pot for Your Plant. 

Although it's not an easy book, if you can persevere, you'll learn a lot. (I have so many links to educational websites because of this post!)

Fertilizing your Philodendron Rojo Congo

Fertiliser is one of the resources for developing tall, luxuriant plants. When you give foliage plants, like philodendrons, routine applications of high nitrogen fertilizer, you'll get bigger, better leaves in return. 

Initially, some generic fertilizer information 

The most popular fertilizers for garden-type plants (pun intended) have a ratio of nitrogen (N), phosphorus (P), and potassium (K). 

On the product label, this is written as "N-P-K" with three corresponding numerals next to it. The numbers show the weight-to-weight ratio of each constituent. 

Nitrogen is primarily responsible for the plant's total shoot growth, or "vegetative growth," which is growth that is not blooming or reproductive in nature.

The development of roots, flowering, and seed germination are all regulated by phosphorus. 

Potassium is necessary for the regulation and operation of plant cells.

Philodendrons are cultivated more for their stunning red leaves than for their flowers. This is why we need a fertiliser with a higher nitrogen-to-phosphorus and potassium ratio. 

A foliar plant should have a 3:1:2 or 3:1:3 N:P: K ratio. Different ratios won't harm it, but a fertilizer with a high nitrogen content is best. 

After discussing fertilizer ratios for foliar plants, let's talk about fertilizer choices:

Slow release fertilizer

Slow-release fertilizers are pellets or capsules that are mixed into the soil and release fertilizer gradually over time when you water your philodendron.

Repotting is a fantastic opportunity to add a delayed-release fertiliser if you choose. Osmocote is among the most well-known brands.

There is controversy around the rate and duration of fertilizer release from slow-release kinds, but that is outside the focus of this article. Some indoor plants are said to endure up to six months, while three to four months may be more reasonable.

Water soluble fertilizer

A conventional quick-release, water-soluble fertilizer could also be applied by dissolving it in water and then watering it as usual.

Ensure that your philodendron receives ample watering so that the soil is wet. In this manner, water will be retained in the soil during fertilizer application rather than flushing out the bottom. Additionally, it helps avoid fertilizer burn.

For philodendrons and other foliage plants, the following fertilizers contain the ideal NPK balance:

So that's everything for now! The general maintenance requirements are the same whether you have a Philodendron Congo Rojo, Black Cardinal, Imperial Red, or Congo Red. They are true scroll-stoppers that are also incredibly simple to cultivate and maintain. Enjoy your red philodendron, and do let me know if you have any questions regarding it in the comments section.

[Are you looking for further advice on gardening and design? Let's chat on Instagram together!]

SOURCES

The genus Philodendron's molecular phylogeny

The Numerous Protective Functions of Anthocyanins in Leaves: Nature's Swiss Army Knife https://edis.ifas.ufl.edu/publication/EP150