Anthurium King of Spades Care: The Science-Based Guide
Anthurium King of Spades care, explained by physiology: why the velvet leaf scorches in sun, the chunky high-oxygen mix that stops root rot, VPD targets, and the Cal-Mag feeding that prevents deformed leaves.
Patrick Ivern · 2026-01-20 · 16 min read
Key Takeaways
- The King of Spades is a hybrid (crystallinum × magnificum lineage), and that hybrid vigor makes it handle ordinary home humidity far better than its fussy parent species — it reacts to its environment rather than being truly fragile.
- The velvet surface is a working lens. Dome-shaped epidermal cells focus dim light for efficiency, which is exactly why direct sun scorches it. Give it bright diffused light (1,000-2,500 fc), and keep it at the lower end of that band for the darkest color.
- Most failures are root failures from a lack of oxygen, not water. Use a chunky, fast-drying mix with 30-40% air-filled porosity and let it dry meaningfully between thorough flushes.
- Brown leaf edges are usually a hydraulic problem. In dry air the velvet leaf loses water faster than the roots refill it, so target a VPD near 0.8-1.0 kPa with gentle airflow rather than just chasing a humidity number.
- Feed lightly but constantly with a complete fertilizer, and add Cal-Mag if you use RO or distilled water. Calcium is immobile, so a steady supply is what keeps new leaves from emerging hooked and deformed.
Introduction
In the world of indoor horticulture, specifically within the niche of Aroid collectors (family Araceae), there is a distinct hierarchy of popularity. One of the most highly sought-after plants is the Anthurium ‘King of Spades’.
For those unfamiliar with it, this plant is quite different from the common Flamingo Flower (Anthurium andraeanum) found in grocery stores.
The King of Spades (often abbreviated as KOS) is a foliage anthurium, valued for its leaves rather than its flowers.
These leaves are heart-shaped, very large, and feature a dark, light-absorbing texture. Owning one is significant for collectors; keeping it healthy is a demonstration of skill.
However, there are many misconceptions about this plant. Common online advice suggests the King of Spades is difficult to grow, requiring greenhouse conditions, extremely pure water, and very high humidity.
This guide aims to correct these misunderstandings by focusing on the plant’s actual physiological needs and environmental requirements.
The reality is that the King of Spades is not necessarily fragile; it simply reacts noticeably to its environment.
It has specific adaptations for survival in tropical understories (and the nurseries where it was bred), which determine how it should be cared for.
By understanding how its leaves process light or how its roots function, care becomes a logical process rather than guesswork.
The Genetic Blueprint: History and Hybrid Vigor
Understanding the plant’s lineage is helpful for understanding its care.
Unlike a species found directly in nature (like Anthurium warocqueanum or Anthurium veitchii), the King of Spades is the result of selective breeding.
The Origin and Mr. HU
In the collector community, the King of Spades is closely associated with Haji Ulih, often referred to as Mr. HU.
Based in Indonesia, he is a breeder who crossed specific velvet-leaved species to create a plant with this specific form and dark coloration.
The King of Spades is widely believed to be a hybrid combination involving:
- Anthurium crystallinum: Provides the silver veins and the velvet texture.
- Anthurium magnificum: Contributes the large size, the square-shaped winged petioles (leaf stems), and the distinct vein pattern.
- Anthurium forgetii: Some suggest this parentage because the top gap of the heart shape (sinus) is closed in some clones, though this is not confirmed.
The Benefits of Hybrid Vigor
This genetic mix is beneficial for indoor growing. In biology, heterosis (hybrid vigor) refers to the tendency of crossbred plants to exhibit qualities stronger than their parents.
Resilience
While A. crystallinum often requires high humidity and A. magnificum can be prone to fungal issues, the King of Spades typically handles standard home conditions (40-50% humidity) much better than its parent species.
Growth Rate
It generally grows faster and develops roots more robustly than pure species.
Variability
Because the King of Spades is often grown from seed rather than clones, there is significant variation between individual plants.
One might have wide silver veins, while another appears nearly black. This results in the term F2 generation (grandchildren of the original cross), which can show a wide range of traits.
The Physiology of Velvet: How the Leaf Works
The most distinct feature of the King of Spades is its texture. It has a matte, velvety appearance (technically called a velutinous surface).
This is a functional adaptation that directly affects light and water requirements.
The Convex Lens Mechanism
If you view a cross-section of a King of Spades leaf under a microscope, the upper cells (epidermis) are shaped like small domes.
The Science
These convex cells function as microscopic lenses. In the low light of a rainforest floor, they capture diffuse light and focus it into the photosynthetic layer below.
The Practical Implication
This allows the plant to be highly efficient at using available light. It effectively maximizes the light it receives.
The Danger
Because these cells focus light, direct sunlight can be very damaging, acting similarly to a magnifying glass. It can burn the cells quickly, causing bleaching or scorch marks.
The King of Spades requires high-quality, diffused light rather than intense, direct sun.
Transpiration and the Cuticle
Waxy plants have a thick cuticle to hold moisture in. Velvet plants have a thinner barrier and a larger surface area due to the textured cells.
The Science
Research on Anthurium shows that water loss (transpiration) is influenced by the leaf structure. The velvet texture increases the surface area available for evaporation.
The Practical Implication
In dry air, a King of Spades can lose water from its leaves faster than the roots can supply it. This causes Marginal Necrosis (browning edges).
The plant is physically drying out from the edges inward because water pressure is too low at the leaf margins.
The Color Black: Anthocyanins
The dark coloration of the King of Spades is due to high levels of anthocyanins and the arrangement of chloroplasts.
The Insight
To maintain the dark color, the plant actually performs better in lower light ranges. In very bright light, the plant may produce protective pigments or reduce chlorophyll, causing the leaf to look reddish or pale green.
For the darkest appearance, keep the plant at the lower end of its recommended light range.
Substrate Engineering: Understanding Soil Physics
This section is critical. Most Anthurium issues stem from root rot, which is typically caused by a lack of oxygen rather than just too much water.
The Epiphytic Nature
In the wild, the parent species of the King of Spades often grow as epiphytes (on trees) or in loose leaf litter, rather than in deep soil.
Root Environment
Their roots are used to constant airflow and a cycle of getting wet followed by drying out quickly.
Velamen
The roots are covered in a spongy tissue called velamen, which absorbs moisture rapidly from humid air or rain.
The Soil Problem: Air-Filled Porosity (AFP)
Standard potting soil can be detrimental to these plants. Fine particles pack together, holding too much water and eliminating air pockets.
The Metric
We look at Air-Filled Porosity (AFP), which is the percentage of the pot’s volume filled with air after being watered and drained.
The Target
A King of Spades prefers an AFP of 30-40%, whereas standard soil is often 5-10%.
The Fix
The substrate needs to resist compaction. This is achieved by using chunky materials.
Ingredient Breakdown
| Ingredient | Role | Function |
|---|---|---|
| Orchid Bark (Pine/Fir) | Structure | Creates large air gaps. Quality bark resists breaking down, keeping the mix airy. |
| Coco Chips (Husk) | Absorption | Large chunks that hold water inside but keep air gaps outside. They release moisture slowly. |
| Pumice | Drainage | Volcanic rock. It is heavy and does not float, creating permanent air pathways. |
| Tree Fern Fiber | Root Surface | Fibrous strands similar to a tree trunk. Epiphytic roots often attach well to this texture. |
| Charcoal | Filtration | Absorbs impurities and helps prevent bacterial buildup in the pot. |
| Sphagnum Moss | Moisture | Holds significant water. Use in moderation to create damp areas without blocking air. |
To make a suitable mix, it is helpful to know the function of each component.
- Orchid bark is the structural backbone. It holds shape, resists compaction, and creates the large air channels velamen roots depend on.
- Coarse pumice or perlite keeps the mix loose and adds drainage weight without holding excess water.
- Coco chips retain a little moisture in their fibers, buffering the mix between waterings without going soggy.
- Horticultural charcoal keeps the mix sweet, adsorbing salts and off-gassing byproducts in a humid, slow-draining pot.
- Worm castings add a gentle, slow-release nutrient charge in the moisture-retentive recipes.
A reliable starting point is a bagged chunky orchid or aroid bark blend like BetterGro Orchid Bark, which you can amend with pumice and charcoal to dial in the air-filled porosity your watering habits call for.
Situation-Specific Soil Recipes
Choose a soil mix based on your personal watering habits.
Recipe A: For Frequent Waterers (High Humidity)
People who water often or grow in enclosed, humid spaces.
This mix drains very quickly. Water passes through easily, pulling oxygen to the roots. It is difficult to overwater with this mix.
- 4 Parts Large Orchid Bark
- 3 Parts Coarse Pumice (or Perlite)
- 2 Parts Coco Chips
- 1 Part Horticultural Charcoal
- 0 Parts Soil/Peat
Note: You must use fertilizer with every watering, as this mix does not retain nutrients well.
Recipe B: For Infrequent Waterers (Dry Home)
People who water less often or live in drier environments.
This mix holds moisture in the fibers while using bark to maintain structure.
- 3 Parts Medium Orchid Bark
- 2 Parts Coco Coir or Tree Fern Fiber
- 2 Parts Perlite
- 1 Part Worm Castings (slow-release nutrients)
- 1 Part Charcoal
Recipe C: The Rehabilitation Mix (For Root Loss)
A plant that has lost its roots and needs to recover.
Provides high humidity with maximum oxygen.
- 70% Damp Sphagnum Moss
- 30% Perlite
Mix loosely; do not pack it down. Place the stem in this mix.
The moss provides humidity to encourage new roots, while perlite prevents it from becoming too soggy.
Light: The Energy Source
Light is the energy source that drives water uptake. Without sufficient light, the plant cannot process water properly. This is why overwatering issues are often linked to insufficient light.
The Bright Indirect Terminology
The term bright indirect light can be vague. Specific measurements are more useful.
The Metric
Foot-Candles (fc) or Lux.
The Target
The King of Spades grows best in 1,000 to 2,500 foot-candles (approx. 10,000 – 25,000 Lux).
The DLI (Daily Light Integral)
This refers to the total amount of light received in a day. The plant needs about 12-14 hours at this intensity.
The Shadow Test
A simple way to test light intensity without a meter.
- Hold your hand 12 inches above the leaf during the brightest time of day.
- Observe the shadow cast.
Too bright (Direct sun). Risk of burning.
Optimal (Bright Indirect).
Too dark. The plant will survive but growth will be slow.
Spectrum Effects: Blue vs. Red
Light spectrum influences the plant’s shape.
Blue Light
Encourages compact, leafy growth. It keeps stems short and foliage dense.
Red Light
Encourages stretching and flowering.
Advice: For the King of Spades, compact foliage is usually preferred. Use Full Spectrum LED grow lights (which look white) rather than purple/red lights. Standard 5000K-6500K shop lights work well if placed 1-2 feet above the plant.
A white full-spectrum panel such as a SANSI 24W grow light sits in that 5000-6500K range and pushes enough intensity to hold the plant at the top of its DLI band without the magenta cast of cheaper diode arrays. Keep it 30-50 cm above the canopy and run it 12-14 hours.
Atmosphere: Humidity and VPD
The King of Spades is often considered difficult because of its humidity requirements. It needs humidity, but stagnant moist air can be harmful.
The Science of VPD (Vapor Pressure Deficit)
Relative humidity percentages (like 70%) are only part of the picture. The plant responds to VPD.
What is it?
VPD is the difference between the moisture in the air and the moisture within the leaf. It measures the air’s drying potential.
High VPD (Hot & Dry)
The air draws water out of the leaf rapidly. The plant closes its pores (stomata) to conserve water, which halts photosynthesis. This leads to stalled growth and dry edges.
The air is saturated, so water cannot evaporate from the leaf. Roots stop taking up water because there is no pull from the leaves. This can lead to root rot and fungal issues.
The Sweet Spot
Aim for a VPD of 0.8 kPa to 1.0 kPa.
Practical VPD Guide
| Temperature | Ideal Humidity Target | Outcome |
|---|---|---|
| 65°F (18°C) | 50% – 60% | Safe. Moderate growth. |
| 75°F (24°C) | 65% – 75% | Ideal. Vigorous growth. |
| 85°F (29°C) | 80% – 90% | Fast growth, but high rot risk without airflow. |
Generally, higher temperatures require higher humidity.
The Stuck Leaf Phenomenon
A common issue with the King of Spades is when a new leaf gets trapped in the sheath, causing tearing.
The Mechanism
The plant produces mucilage (a natural lubricant) to help the leaf emerge. In dry air, this lubricant dries out and acts like glue, trapping the leaf.
The Fix
- Prevention: Increase humidity when a new spike appears.
- Correction: If a leaf is stuck, do not force it. Apply warm water with a Q-tip along the seam of the sheath. This rehydrates the lubricant. Wait 10 minutes, then gently try to free the tip.
First Report of Colleters in Araceae: Anthurium andraeanum Reveals Diverse Mucilage Glands
Airflow: Preventing Rot
If humidity is increased (e.g., in a cabinet), you must have airflow. Stagnant moisture encourages bacteria and fungus.
The Fan Rule
Aim for a gentle breeze that causes slight movement in the leaves. This evaporates the stagnant layer of air near the leaf surface, ensuring gas exchange and preventing condensation.
Water Chemistry and Hydraulics
Water transports nutrients. If water uptake is compromised, nutrients cannot reach the plant.
Determining When to Water
Avoid watering on a strict schedule. Instead, check the moisture level.
1. The Chopstick Test
Insert a wooden skewer to the bottom of the pot. Leave it for 5 minutes. Remove it.
- Damp/Dark Wood: Do not water.
- Dry/Light Wood: Water immediately.
2. The Flush Technique
When watering, run water through the pot thoroughly.
Why?
This removes stale air from the bottom of the pot and pulls fresh oxygen into the root zone. It also washes away accumulated salts.
Water Quality: A Common Issue
Velvet anthuriums are sensitive to accumulated salts and fluoride.
Symptoms
Brown tips that slowly expand, often with a yellow halo.
The Solution
Reverse Osmosis (RO) water or Distilled water.
Rainwater (check for pests).
Acceptable: Tap water left out for 24 hours (this removes chlorine, but not chloramine or fluoride). If using tap water, flush the soil heavily once a month to remove salts.
Nutrition: Feeding Requirements
Anthuriums are light but consistent feeders. They prefer steady, low doses of nutrients.
The Need for Calcium & Magnesium
Anthuriums have a high requirement for Calcium.
Calcium (Ca)
This is a key structural component of cell walls. It is immobile within the plant, meaning the plant cannot move calcium from old leaves to new ones. It needs a continuous supply from the roots during growth.
Deficiency Sign
New leaves appear deformed, hooked, or damaged at the tips.
Magnesium (Mg)
This is essential for chlorophyll. It is mobile, so the plant can move it from old leaves to new ones.
Deficiency Sign
Yellowing between the veins on the oldest leaves.
The Feeding Recipe
- Base Fertilizer: Use a balanced liquid fertilizer with all 16 nutrients. A urea-free formula like Dyna-Gro Foliage-Pro 9-3-6 is a good fit here because it already includes calcium and magnesium, which most bloom-style fertilizers omit.
- Dosage: Use 1/4 to 1/2 of the recommended strength.
- Frequency: Feed with every watering (Weakly, Weekly).
- Supplement: If you water with RO or distilled water (which carry no minerals), add a dedicated Cal-Mag supplement such as Botanicare Cal-Mag Plus at a few mL per gallon. Calcium is immobile, so this steady supply is what prevents the hooked, deformed new leaves.
- Silicon: Silicon helps strengthen cell walls. Add this to your water first to avoid chemical reactions with other nutrients.
Pest Management
The King of Spades is particularly susceptible to Spider Mites and Thrips.
Spider Mites (Tetranychidae)
Susceptibility
They thrive in hot, dry conditions, which also stress the plant.
Signs
- Stippling: Tiny yellow/white dots on the leaf.
- Appearance: The leaf looks dull or dusty.
- Webbing: Fine strands near the leaf stem.
Life Cycle
They can reproduce in 5-7 days in warm weather.
Control Strategy
Spray leaves with water to knock off the majority of the mites.
Use a mixture of Water, Isopropyl Alcohol (4:1), and a drop of dish soap. Wipe or spray to kill mites on contact. Repeat every 3 days for 2 weeks.
Release predatory mites (Phytoseiulus persimilis), which feed on spider mites.
Thrips (Thripidae)
The Challenge
Thrips lay eggs inside the leaf tissue, where surface sprays cannot reach them.
Signs
- Silvering: Silvery patches on the leaf surface.
- Frass: Tiny black dots that smear.
- Deformity: Thrips feed on new growth, causing leaves to emerge twisted.
Control Strategy
- Spinosad first: A spray containing Spinosad is highly effective against thrips, including larvae feeding in new growth, and is the safest first line for an indoor plant.
- Sticky traps and pruning: Blue sticky cards catch the winged adults, and cutting off heavily deformed new leaves removes the eggs laid inside that tissue.
- Systemics as a last resort: Imidacloprid soil granules work, but neonicotinoids are highly toxic to bees and other pollinators and translocate into pollen and guttation droplets. Reserve them for a stubborn indoor infestation that mechanical and Spinosad treatment cannot clear, keep the treated plant away from any flowering or outdoor plants, and follow the label exactly.
- Frequency: Whatever you choose, treatment must continue weekly for 4-6 weeks to catch newly hatching larvae.
Pathology: Bacterial vs. Fungal
| Feature | Bacterial Blight (Xanthomonas) | Fungal Leaf Spot (Septoria/Colletotrichum) |
|---|---|---|
| Appearance | V-Shaped lesions at leaf edges. | Circular or irregular spots. |
| Halo | distinct yellow halo. | Concentric rings or less distinct halo. |
| Texture | Water-soaked or greasy look. | Dry or powdery. |
| Smell | May smell unpleasant. | Usually odorless. |
| Spread | Rapid, systemic movement. | Slower, localized spread. |
| Action | ISOLATE IMMEDIATELY. Remove infected leaves with sterile tools. Discard plant if stem is infected. | Treat with fungicide and improve airflow. |
It is important to distinguish between fungal infections and Bacterial Blight, as the latter is much more severe.
The Guttation Risk
Bacterial blight often enters through pores at the leaf tip (hydathodes) during guttation (when the plant releases water droplets).
If you see water droplets on leaf tips, reduce humidity and increase airflow to dry them quickly.
Acclimation and Propagation
Acclimating New Plants
The first two weeks after a plant arrives are critical, as it transitions from a nursery to a home environment.
Protocol
Avoid disturbing the roots immediately to prevent additional stress.
Water lightly if the soil is dry.
Place the plant in a clear storage bin with the lid cracked open to maintain high humidity.
Gradually open the lid more over two weeks to allow the plant to adjust to lower humidity.
Propagation
The King of Spades is typically propagated via stem cuttings.
- Wait until the stem has aerial roots visible.
- Moss Wrap: Wrap damp sphagnum moss around the aerial roots and cover with plastic.
- Wait Again: Allow 3-4 weeks for roots to develop in the moss.
- Cut: Remove the top section below the new roots and pot it.
- Regrowth: Leave the bottom section in the pot to sprout new growth from dormant buds.
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