Philodendron Martianum Care: A Horticulturist’s Growing Secrets!

The Philodendron Martianum is a truly unusual philodendron, but whilst it’s relatively rare, it’s fairly easy to care for!

In this in-depth care guide, I’ll share the top tips and tricks I used as a Horticulturist to look after many of these thick, tropical beauties!

Quick Philodendron Martianum Care Breakdown

  • Soil: Well-draining, chunky
  • Light: Bright, indirect light
  • Watering: Soil should be kept lightly moist
  • Temperature: Between 18-30°C
  • Humidity: Between 50-70%+
  • Fertilizer: Once per month during spring & summer

Appearance and Plant Identification

Identifiable by its fleshy deep green leaves and petioles, its thick foliage allows it retain water very easily; as a result, this species does not require as much water as its average philo counterparts.

Other common names for the philodendron Martianum include the ‘flask philodendron‘, and the ‘fat boy philodendron‘. You’ll likely see ‘fat boy’ on plant tags!

Philodendron Martianum Plant Care

potted philodendron martianum plants with healthy leaves


Native to the lush canopies of Brazil’s rainforests, many are quick to believe that the Philodendron Martianum is a low-light plant, but that couldn’t be further from the truth.

It thrives in 6-8 hours of bright, indirect light, and will grow richer and thicker foliage because of it.

🌱 What Exactly Is Bright, Indirect Light?

Measuring light by eye is tricky and completely subjective. That’s why I recommend investing in a handy light detector so you can make sure your philodendron reaches its full growth potential.

I love and use this one. It measures in foot candles (FC) and it’s fairly cheap!

Pro Tip: We use light meters all the time in Botanical Gardens!

🌱 What Type of Light Is Needed for Maintenance and Growth?

This beauty requires a minimum of 200 FC to maintain its health, BUT the ideal light range should be around 400 FC to ensure good growth.


When caring for an epiphytic plant such as the Philodendron Martianum, you’ll want to provide a soil that’s loose, well-draining, and rich in organic matter.

The loose, chunky material allows better air circulation around the roots.

🌱 Recommended Soil Mix For Philodendron Martianum

I’ve noted my DIY aroid potting mix recipe below! It’s a horticultural formulation I used to use for philodendron ‘enclosures’ when I worked for a botanical garden.

Diy Aroid Potting Mix Recipe

If you want to save time (and potentially a little money!) you can also opt for a pre-made mix. I’ve had great success with Fox Farms’ Ocean Forest Mix and Noot’s Organic Coir Mix in the past.

My Philodendron Red Moon and Philodendron Quercifolium love the stuff. I’ll occasionally just add a little more perlite and worm castings (optional), but that’s it.


Remember those thick leaves and fleshy petioles? These are common characteristics of a plant that has succulent-like tendencies. And what do succulent plants hate the most? Overwatering.

That thick foliage means that the Martianum doesn’t require super frequent waterings. Only water your Philodendron Martianum when the top 1-3 inches of soil has almost dried up. 

Rather than stick to a strict watering schedule i.e. once a week, try testing the soil to see if your plant really needs a drink.

a philodendron fat boy dropping in a pot

🌱 How to Tell When Your Plant Needs Water

The chopstick technique is a pretty effective method of determining the moisture level of the soil.

  • Place a chopstick a few inches deep into the potting mix (though be mindful of the main stem). Leave it for 30-60 minutes.
  • Then observe the chopstick:
    • Soil that is very wet will stick to the chopstick, and the chopstick itself might turn a darker color.
    • Dry soil will be harder to get the chopstick to pierce through the soil, and no soil will cling onto the chopstick.


Ideally, your Philodendron Martianum should live in a temperature range of 18-30°C (65-95°F). The temperature should never dip below 15°C (60°F).

Cold temperatures = stunted growth. Keep away from drafty windows and AC vents.


The ideal humidity range for the Fat Boy Philodendron is roughly in the range of 50% to 70% humidity.

But, the higher the better! Higher humidity lends to thicker and plumper leaves.

🌱 How to Increase Humidity Levels Indoors

When it comes to increasing humidity levels for your plants, these are two of the best options:

  1. Purchase a small humidifier (100% effective)
  2. Grouping your plants (50-60% effective)

The humidifier is straightforward, but what is grouping, you may ask? Grouping is when you physically group your plants in close proximity to one another.

Plants expel water vapor from their leaves (this is a process known as transpiration). When a group of plants all engage in transpiration, humidity levels naturally begin to increase.

Fertilizer & Growth

🌱 How Large Does a Philodendron Martianum Grow? Are they Fast Growing?

At full maturity, you can expect a philodendron martianum to reach a height of about 1 to 2 feet tall, and spread 2 to 3 feet wide. Their leaves alone can reach up to 18 inches long.

The philodendron martianum is a slow-growing plant, so it’s likely to take a few a good 5-10 years to see that maturity.

🌱 Best Fertilizers for Philodendron Martianum

For best results, I recommend purchasing a complete liquid fertilizer free of urea. Dyna grow pro, the 7-9-5 formulation, does exactly that. It contains all 16 macro and micronutrients your philodendron will need.

Plus, it’s very low in heavy residue salts which over time will lead to root burn.

Fish emulsion is another excellent organic option for fertilizing your plants- it is slow releasing and gives your philodendron a boost of nutrients needed to grow.

It’s pretty stinky though so not one to use in your home!

🌱 When to Fertilize Your Plant

Ideally, the best time to fertilize your Philodendron Martianum is once a month during its active growing period (from Spring through to Summer), and slow down or completely stop in Fall and Winter.

two mature philodendron martianum plants

Propagating a Philodendron Martianum

Seems a little scary but it’s pretty easy! The best method of propagating a Philodendron Martianum is by dividing the mother plant into smaller sections and repotting.

How to Propagate Your Philodendron Martianum via Division

  1. Start by sterilizing your equipment. Wiping your garden knife with rubbing alcohol or a 1:10 bleach/water solution will help ensure no unwanted bacteria affects your plant.
  2. Remove your philodendron from its pot and inspect the root system for the thick stem in the center.
  3. Decide how many divisions you would like to take from the plant. Typically for a large martianum, you can get 3 or 4 divisions; each division should have at least a few leaves on it.
  4. Take your knife and cut through the stem, making separate divisions of the plant with roots included on each one.
  5. Repot each individual division into a separate pot with the appropriate soil. You’ll want to keep the soil lightly moist to mitigate the risk of transplant shock.
  6. The best sign of a successful propagation is when you begin to notice new growth forming from the division. If you’re unsure the division has begun to root, give your plant a gentle tug; if you’re met with any resistance, then this is a great sign that the plant has established its roots in the soil.


🌱 How Often Should You Repot?

Even though it’s a slow-growing plant, I recommend repotting your martianum every 1 to 2 years. Repotting is an excellent way to replenish the potting mix and give air circulation to the plant root system.

Gradually size up your plant pot, only selecting a planter that is 1-2 inches larger than the previous one (this prevents root rot!).

🌱 Signs Your Plant Needs to Be Repotted

Oftentimes, a plant needs to be repotted when its root system has become too big for the current pot that it’s in.

The most common sign that a plant needs repotting include:

  • Stunted growth
  • Roots peeking out from the drainage holes

Is Pruning Necessary for this Plant?

Because of this plant’s slow-growing nature, pruning is not a necessity for this plant’s upkeep. I only used to trim away diseased, damaged, or infested leaves.

Plant Toxicity

Like with all other species of philodendron, the martianum is toxic to both animals and humans.

Ingestion of the philodendron is known to cause:

  • irritation to the mouth, esophagus, and intestinal tract
  • On rare occasions, upper respiratory swelling can occur.
a close up of philodendron fat boy stems
Look at those signature stems, @

Common Pests

🐞 Mealybugs

Mealybugs are small, oval-shaped white insects that tend to rear their ugly head around tropical houseplants. Mealybugs often congregate in colonies that suck the nutrients right out from your plant.

The most common sign of mealybugs is the cotton-like residue that they leave behind on the foliage of your plants.

Here are some tips to control the presence of mealybugs:

  • Prune any dead or damaged foliage that has been affected by mealybugs
  • Wipe down your plants with a cotton ball soaked in 70% isopropyl alcohol
  • Apply neem oil directly to the mealybugs (this is especially effective with juvenile pests)

🐞 Scale

Just like mealybugs, scale is another sap-sucking insect that can lead to trouble if left untreated. Scale can cause yellow, dying foliage in addition to stunted plant growth.

Scale can be ever-changing in appearance and are often left unseen by gardeners until they start to cause serious damage. For the most part, scale is identifiable as small, oval insects that can range in color from brown, to white, to yellow.

Some control methods include:

  • Spraying neem oil on your plant. This can be done both as a preventative measure during the dormant season, as well as when you have an active infestation.
  • Prune and remove any affected foliage.

Common Diseases

👉 Fungal Leaf Spot

A combination of wet foliage combined with warm temperatures can be a recipe for fungal leaf spot, which makes the philodendron martianum a prime victim of this disease.

Fungal leaf spot can manifest itself in many different ways, though the most common sign include dark spots on the foliage of your plants. These spots are often brown with a light border around them.

You can prevent the spread of fungal leaf spot by:

  • Watering your plant as close to the base as possible, avoiding getting the foliage wet.
  • Immediately pruning any infected foliage and destroying it completely (either by burning or placing it in an airtight plastic bag).

Help! What’s Wrong with my Philodendron Martianum

👉Yellowing, Wilting Foliage

If your philodendron martianum has turned yellow and the foliage appears to be wilting, this can be a telltale sign that your plant has been overwatered.

👉 Brown Foliage

On the flip side, brown foliage is often a sign that your philodendron is being under watered and is starting to dry out. While the martianum can withstand a bit of dry soil, make sure not to leave it out to dry for too long, or the foliage can suffer.

👉 Dry, Brown Patches on Leaves

If your plant is experiencing dry, brown patches on the leaves, this is an indicator that your plant is experiencing too much direct sunlight (aka scorch marks).

I highly recommend revisiting our section on light for a great refresher on how much light is appropriate for the philodendron martianum.

FAQ – You Ask, I Answer

Can You Grow Philodendron Martianum from Seeds?

Yes, but it’s not a beginner-friendly method at all. Philodendron Martianum seeds are hard to cultivate from a home-grown plant, and have a low likelihood of germinating.

Should I Mist my Philodendron Martianum?

Misting has been proven to be ineffective in raising humidity levels. Not to mention, wetting the foliage of your plants can lead to further disease down the road (such as fungal leaf spot, for example).

Instead, I prefer to use other options such as utilizing an electric humidifier or grouping my plants together (see my section above on “Humidity” for more information).

🌱 Continue Your Journey of Discovery

photo of Charlotte Bailey founder of Oh So Garden


Charlotte Bailey

Charlotte is a Qualified Royal Horticultural Society Horticulturist, plant conservationist, and founder of Oh So Garden. Armed with a background in Plant Science (BSc Hons, MSc) and 5 years of hands-on experience in the field, her in-depth guides are read by over 100,000 people every month.

For her work, she's been awarded the title of Yale Young Global Scholar, and been featured as a garden and houseplant expert across major networks and national publications such as Homes and Garden, Best Life, Gardeningetc,, BHG, Real Homes, and Country Living. You can find her on Linkedin.

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