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Hoya Krimson Queen- Royal Plant The Ultimate Care Guide

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A star is born every time the Krimson Queen Hoya flowers – in fact, two stars are born, one inside the other. And not any stars, mind you, porcelain stars

Hoya Krimson Queen, also known as the Hoya carnosa ‘Tricolor,’ is a variegated wax plant with porcelain-like flower clusters. Each flower in the cluster is star-shaped and opens to reveal a contrasting crimson-colored inner flower with a similar five-petaled star-shaped configuration. 

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Nature offers ample opportunities for us to be awestruck – from the giant Sequoia sempervirens (Coast Redwood) in the Redwood National Park, standing at an astounding 380 feet tall, to the delicate beauty of the Hoya carnosa ‘Tricolor’ (Hoya Krimson Queen), nature continuously demonstrates its ability to impress. 

Introduction – Hoya Krimson Queen, the Royal Plant 

The Hoya genus is part of the Asclepiadaceae family, a family of plants that consists of 320 genera totaling more than 2000 species. The family, also known as the Milkweed family is instrumental in ensuring the future of the Monarch Butterfly. 

Hoya Krimson Queen
Hoya Krimson Queen

Monarch caterpillars feed exclusively on milkweed leaves, the only host plant for this iconic butterfly species. As such, milkweed is critical for the survival of monarchs. Without it, they cannot complete their life cycle, and their populations decline.

National Wildlife Federation

Most importantly for us at this stage, the milkweed family gave us the Hoya carnosa, and science gave us the Tri-color hybrid (Patent no. 2950).

The Hoya carnosa is generally referred to as the wax plant and is native to Asia, Australia, India, and the Pacific islands. 

The Hoya Krimson Queen is one of ten hybrids (five of them patented) from the wax plant (Hoya carnosa) species and is also referred to as porcelain flower and wax vine. These plants are primarily cultivated for the indoor gardening market, though their beauty is only now gaining popularity. 

Hoya Krimson Queen Needs 

Success in growing any plant indoors largely depends on our ability to replicate its natural habitat. I stress the plant’s lineage and origin for this reason.

If we know where it came from and its natural habitat environment, we can more easily create a space that will allow our plant to feel at home. 

The Hoya carnosa‘s natural habitat is tropical, partially arid, where they grow on (epiphyte) and under larger trees. A unique feature of the Hoya carnosa is its adaptation to lower humidity levels and higher temperatures. 

Like pineapples, the wax plant has evolved a mechanism that conserves moisture by not transpiring during the day. The mechanism known as CAM (crassulacean acid metabolism) allows photosynthesis during the day without CO2 absorption. 

CO2 is absorbed during the night and stored for use when light is available for creating carbohydrates that sustain the plant.

This is a radically oversimplified explanation, but the point is that the wax plant has evolved to conserve moisture, using the same mechanisms succulents use. 

The essential elements that ensure sustainable life for every indoor plant are: 

  • Soil characteristics – water management, aeration, consistency, constitution, pH, and nutritional content. 
  • Water needs – availability, need for dry periods, and quantity. 
  • Preferred light levels. 
  • Preferred temperatures. 
  • Preferred humidity levels.
  • Nutritional needs – macronutrients and micronutrients – in total, 17 essential nutrients. 
  • Propagation means – sexual (pollination means) and asexual propagation. 
  • Potting and repotting requirements. 
  • Managing blooms. 
  • Potential diseases. 
  • Potential pests. 

These essential elements vary according to plant species, a product of evolutionary adaptation to their natural habitat.

Top Tip: While we can acclimatize plants through hardening off, we cannot change their natural requirements. 

So let’s see what the Krimson Queen Hoya, a hybrid of the wax plant, needs to thrive. 

Wax plants are epiphytes, meaning that in their natural habitat, they grow on living plants (but not as parasites).

Some may even germinate in the crevice of a tree crotch, sending additional roots down to the ground for moisture and nutrient supplementation. 

Others may germinate on the forest floor and vine up the tree for better access to light. These factors are important when considering how to best care for your royal plant, the Hoya Krimson Queen.

Let’s start with the soil requirements. 

All About Hoya Krimson Queen Soil Requirements 

Essentially what you’re looking for in a healthy soil mix is a balance between retaining water while ensuring good drainage, providing adequate aeration (avoiding anaerobic conditions), maintaining the right pH, and ensuring the soil has sufficient cation exchange capacity (CEC). 

If you’ve had the opportunity to read my Composting Masterclass book, you’d understand why I’m so passionate about using compost, even in potting soil. A good potting mix for your Hoya Krimson Queen should include the following ingredients in the given proportions: 

  • One part compost 
  • Two parts coconut coir 
  • Half a part of pumice (or perlite) 
  • Half a part expanded shale, or LECA (lightweight expanded clay aggregate) 

Each of the above serves a specific purpose in emulating the Hoya carnosa‘s natural habitat. 

Picture of pots lying on side with compost perlite and vermiculite piles in front of them
Potting Mix Ingredients


Adding compost to potting soil has several benefits; an essential one is the soil’s increased ability to keep nutrients available for plant access.

Cation exchange capacity (CEC) can be seen as magnetizing the soil to keep water and some cation-charged nutrients in the soil. Soils with low CEC (like sand) cannot retain moisture and nutrients; they simply flow through the soil. 

Compost boosts a soil’s CEC, making the plant’s moisture and nutrients more readily available. Compost also helps the soil manage pH levels, promotes better drainage, and encourages the presence of essential microorganisms beneficial to the plant’s health and resilience. 

Coconut Coir 

While sphagnum peat moss is often given as the default potting mix, I have found that coconut coir is a better option. One of the main reasons I prefer coconut coir is its ready inclination to accept watering. 

Peat moss is notoriously difficult to wet once dry, requiring double watering, the first to break the nonabsorbency, and the second to wet the plant. I don’t know about you, but I don’t have time to waste. 

Also, coconut coir, unlike peat moss, is renewable. Mining peat moss releases copious amounts of methane gas into the environment.

On the other hand, coconut coir is a waste byproduct of coconut harvesting and processing and is abundantly renewable and available. 

Coconut coir has outstanding water retention and drainage abilities, with most forms of coir holding up to nine times their weight in water. This natural air-to-water ratio helps nourish plant root systems without oversaturating them or putting them at risk of root rot.

Coconut Coir
<strong>Coconut Coir<strong>

Pumice or Perlite 

Some gardeners may advise using sand in a potting mix – it has no value other than reducing the CEC. Use perlite instead; it provides better drainage while boosting aeration levels. 

Wet it before incorporating it into the mix to ensure it doesn’t float to the top when watered and also limit dust levels. Perlite dust can be harmful when inhaled. 

Perlite in a green cup
Perlite Potting mix ingredient

Unlike perlite, pumice manages water well while boosting aeration. I would err on using less pumice as the water retention capacity is higher than either sand or perlite. Still, many succulent enthusiasts swear by it. Some of their reasons include:

  • Pumice improves drainage. 
  • It keeps soils from becoming anaerobic and water-bound, preventing root rot. 
  • It is hygroscopic and, in cooler weather, can retain moisture for up to 48 hours. Tiny channels in the volcanic gravel make water and nutrition storage possible.   
  • It releases moisture at a steady, slow rate. 
  • It helps to aerate the soil, boosting its oxygen levels to the required 6%. 
  • It provides some of the trace elements required for plant health. 
  • It has no health risks associated with it. 

Expanded Shale or LECA 

When shale is crushed and heated to 2,000 degrees Fahrenheit in a rotary kiln, expanded (vitrified) shale is the product. Expanded shale, like pumice, does not break down like organic materials, so the soil stays aerated for years. 

Bonsai and succulent growers use expanded shale to make potting soils that are airy, light, and water-retentive. Adding expanded shale to our Hoya Krimson Queen potting soil stimulates the plant’s natural habitat: airy, light, and managed water retention. 

LECA has similar properties and is an alternative if finding expanded shale is challenging. LECA also functions as a good mulch to reduce evaporation rates, beautifying the exposed soil surface. 

large expanded clay aggregate

Krimson Queen Hoya Watering Needs 

Watering Your Hoya
Watering Your Hoya

Because of the waxy nature of the plant, root rot on H. carnosa can go unnoticed – until it’s too late. A tell-tale sign is brown to black lesions with mushy roots that are gray to black.

Look for weblike red-brown mycelium across the leaves and the potting medium’s surface. 

The wax plant is a semi-woody vine with some succulent characteristics. Its greatest threat is your love expressed as watering it. If in doubt, don’t water for a day or two more. Their love language is dry roots, so give them that. 

Overwatering is the main reason why potted plants die. When surrounded by water, roots cannot absorb oxygen; they require water and oxygen.  

Porous clay pots need more regular watering than nonporous, glazed, or plastic pots because water evaporates quickly from their sides. The general rule is to only water when necessary. To decide when to water, one may utilize the following techniques: 

  • Touch the soil: The most accurate test for soil moisture is to feel how dry the potting soil feels. If the mixture is dry at your fingertip after inserting your finger up to the second digit, it needs water. 
  • When potting mix in a clay pot starts to dry up, it shrinks away from the pot’s sides. Use a stick or your knuckles to tap the pot’s side. Water is required if the sound is hollow; if the sound is dull, the soil is moist. 
  • Estimate weight: It’s easy to see a weight reduction as potting mixtures dry up. 
  • Assess soil color: As potting combinations dry, their color will shift from dark to lighter. 

When watering is necessary, water deeply. Apply water until the bottom of the pot is completely submerged.

This removes accumulated salts and ensures that most of the roots in the bottom two-thirds of the pot get enough water. Empty the tray – Don’t let the pot sit in the water that runs out. 

It’s important to your Royal plant’s health to allow it to enter some dormancy during winter. You can help it by reducing water during this time and stopping any fertilizing in October. 

Hoya Krimson Queen Preferred Light Levels 

Which plants will thrive in our houses (or perish) depends on the environment we offer. Ample light is one of the most crucial environmental elements when growing plants inside. 

Light gives plants the energy they require to produce nourishment. Foot candles are a standard unit of measurement for light (ft-c).

While outdoor light intensity on a bright, sunny day may surpass 10,000 ft-c, the interior of a well-lit home is frequently less than 100 ft-c. Plants’ need for light intensity varies widely.

Plant light requirements for indoor plants can be categorized thus: 

  • Low (minimum 100 ft-c, 75 to 200 preferred for good growth) 
  • Medium (minimum 100 to 150 ft-c, 200 to 500 preferred) 
  • High (minimum 150 to 1000 ft-c, 500 to 1000 preferred) 
  • Very high (minimum 1000 ft-c, 1000+ preferred) 

Medium-light plants like the wax plant thrive in eastern exposures or a few feet from these light sources.

Any specific site’s lighting conditions will change depending on the time of year (length of day and the sun’s angle), exterior tree shading, window treatments, wall color light reflection, and the actual location. Affordable light meters are a wise purchase if indoor gardening matters to you. 

For most plants, sixteen hours of light and eight hours of darkness is sufficient, and there must be some darkness for a minimum of 4 hours per 24-hour cycle.

In its natural habitat, the Hoya Krimson Queen’s parents are used to 10 hours of light (at about 125 ft-c) and 14 hours of darkness. 


Photoperiodism is the term for the responses of plants to the relative duration of light and dark periods. For many years reference to photoperiodism implied that the light period was the more essential for plant responses.

However, research has shown that every day’s dark period is more critical for some biological needs – like flower production 

While it is not true that all plants require darkness to initiate flower and fruit formation, the Hoya genus requires at least 4 hours of darkness to promote flower formation.

Other plants, like tomatoes, are day-neutral (the whole nightshade family is day-neutral).  

Our Hoya Krimson Queen is a long-day plant, and the poinsettias mentioned above are short-day plants. The nightshade family (tomatoes, potatoes, eggplants, etc.) are day-neutral plants.

The point is that unless our Hoya has some darkness, it will be less inclined to bloom. If you listen carefully, you’ll hear them singing George Benson’s “Give me the night.” 

Flowering Hoya Krimson Queen
Flowering Hoya Krimson Queen

Preferred Temperatures for Growing Hoya Krimson Queen 

Our beautiful, delicate, yet strong Krimson Queen Hoya is a tropical plant, able only to grow outdoors in USDA Hardiness Zones 10b and 12 (where they can be planted year-round).

Floridians can grow the Krimson Queen Hoya (and most aroids) outdoors – lucky fish. 

Wax plants are very susceptible to temperatures below 40° F and should be sheltered in colder temperatures.

They like room temperatures of 68 to 75 degrees Fahrenheit during the day and 60 to 65 degrees at night.

Incidentally, this is the ideal room temperature in homes, too (68 to 76 degrees Fahrenheit). 

Winter cold causes chlorosis to appear first on the lower leaves. Various cold-protection methods can help avoid your Krimson Queen Hoya from becoming chilled.

Excessively bright light or a lack of nourishment can also cause light-colored leaves.  

Plant color is best assured with correct light levels and following recommended fertilizer application rates. Also, guard against drastic changes in temperatures that draughts may cause.  

Preferred Humidity Levels for Caring for Hoya Krimson Queen 

One thing you don’t have to worry about in pursuit of your Krimson Queen’s happiness is humidity. While aroids (Philodendron, Monstera, etc.) need a humidity level above 60%, the Hoya genus will do well with half of that (30%).

Their natural habitat is tropical, but not rainforests where humidity levels can be high.  

Krimson Queen Hoya will thrive where relative humidity levels of between 30 and 40 percent are maintained – which is quite low, so I don’t even consider ensuring it. Just don’t try and grow them with your aroids.  

Hoya Krimson Queen Fertilizer Needs 

Across the United States, gardeners have, on average, 200 effective growing days per year to create beauty, function, and fabulous garden features using plants.  

To optimize those days, gardeners need to provide each plant with its preferred environment, soil conditions, and water supply while meeting its nutritional needs and minimizing the threat of pests and diseases. 

While on the topic of added fertility, it’s important to note that the role of nitrogen (and magnesium) is primarily to boost chlorophyll production.

Your Hoya Krimson Queen is naturally variegated, so too much green (chlorophyll) may not be what you want. 

Controlled-release, slow-release, or liquid fertilizers are preferred ways of providing nitrogen, potassium, and phosphorus to container plants. 

These fertilizers can be used separately or in tandem. Micronutrients such as copper, iron, zinc, boron, and manganese are also required by plants and can be provided by a micronutrient solution. Note the difference: 

  • Controlled release: These are synthetic fertilizers coated with materials to reduce their immediate solubility and availability to plants. 
  • Slow-release: Can be organic or synthetic. The release rate is a product of soil temperature, particle size, and the growing medium’s organic content and microbial life
  • Liquid fertilizer: This allows you to replace leached nutrients after extended rainfall quickly. Best suited for established plants. 
  • Foliar fertilizer: Not recommended for Hoya, but if used on your other plants, dilute several times to avoid burning plant foliage and spray under the leaf for best absorption. It is not a substitute for either of the top three options – merely an addition if needed. 
  • Granular fertilizer is not recommended for containerized plants as the risk of burning the roots is too high. 

Hoya plants need at least 30 days of dormancy to return invigorated, providing you with new growth. Preceding that season of dormancy, the plant should have six weeks of ever-decreasing water and fertilizer inputs.  

Using Epsom Salts 

Epsom salt (magnesium sulfate) lowers the pH and provides magnesium and sulfur, two nutrients often deficient in alkaline soils. Benefits of magnesium for your Krimson Queen include: 

  • Aids photosynthesis by helping your Hoya create chlorophyll 
  • Promotes healthy cell division and protein formation 
  • Increases the Hoya’s ability to retain water 
  • Allows the Hoya to take in and use phosphorus 

Magnesium has a poor cation exchange capacity (CEC), i.e., it binds poorly to soil particles. The only way your plant gets access to it is if it remains in situ near the roots. 

Hoya Krimson Queen Propagation 

Hoya Cutting with Ariel root
Hoya Cutting with Ariel root

Use stem cuttings to propagate your Hoya Krimson Queen. How you generate roots depends on your preferences and the accessibility of the various growing mediums. 

You have three options for growing your cutting: directly in the ground, submerged in water, or in a propagation media like pumice or coconut coir. 

Spring or summer are the ideal times to propagate your Hoya Krimson Queen. You can do it in another season, but it will take considerably longer. 

I’ve included a step-by-step guide that you may use to effectively propagate your Hoya: 

  • Select a cutting that is not too woody, immature, and without blossoms. The propagation process will be sped up if it has a couple of leaves. 
  • Sterilize your pruning shears using rubbing alcohol or boiling water to ensure no bacteria, virus, or fungal contamination is introduced when cutting. 
  • Cut the stem at a 45-degree diagonal just below a node. Diagonal cuts increase the stem’s exposed area, increasing the growth potential 
  • I always use some cinnamon on the parent’s wound to act as a disinfectant. On the cutting, dip the end into growth hormone or vitamin B to boost growth. 
  • Prepare your rooting medium of choice. If you choose water, make sure the water is at room temperature. I recommend distilled water for this purpose. Alternatively, use wet coconut coir to house the cutting – I prefer the latter. 
  • Remove the leaves closest to the node. Don’t include any leaves into the coconut coir as they tend to rot. 
  • Make certain the cutting’s node is in contact with the rooting medium. 
  • Ensure the cutting remained warm from below using a heat mat if possible 
  • Make sure your cutting is in a well-lit place but avoid direct sun or too much light at this stage. 
  • Replant the cutting once you see roots building that are at least a couple of inches long and feeder roots have started to build 

Being patient is both the most crucial and hardest thing to do, at least for me. Nothing happening for weeks on end is quite normal. 

For your cutting to be ready to be planted in a regular Hoya potting mix, it may take a few weeks to several months for roots and new leaves to develop. 

Water and Humidity Management for Cuttings 

Hoya cuttings in water
Hoya cuttings in water

After cutting material is harvested from stock plants, water management becomes one of the most critical factors in propagation. Mist the unrooted cuttings frequently.  

Just sprinkle enough water over the soil to keep it moist (not soggy). Reduce the frequency of watering after roots reach the bottom of the pots so that the potting material can get close to being completely dry before the next irrigation. 

From an unrooted, single-node cutting, it takes between 5 to 11 months to create a finished wax plant with a 6- to an 8-inch-long vine. Two cuttings can be rooted in a single 3-inch pot, three to four per 4-inch pot.  

Being patient is both the most crucial and hardest thing to do, at least for me. Nothing happening for weeks on end is very normal.

Potting Hoya Krimson Queen 

Use a pot with drainage holes because you’ll need well-draining soil and don’t want your Hoya Krimson Queen to get wet feet.

Excess water must be able to drain freely through drainage holes, so don’t cover them with pebbles. 

Krimson Queen Hoya Management 

Wax plants should be planted in a fibrous, acidic potting soil rich in compost and mixed with coconut coir (see above) and in partial shade.  

After flowering, plants should be allowed to become dormant by reducing watering and fertilizer applications during the cool months.

In the summer, plants should be allowed to dry between deep waterings.  

The stems of this plant can cascade over the side of a container with a very well-drained medium to display the waxy foliage and unique blooms. 

Is the Krimson Queen Hoya Toxic? 

There is no toxicity in the Hoya Krimson Queen. However, the milky white sap they generate is poisonous.

Although hoya plants are not harmful to cats and dogs, they nonetheless have the potential to harm them.

Hoya leaves can cause cats and dogs to throw up, thus they are not designed to consume large amounts of them. 

Potential Challenges to Growing Hoya Krimson Queen 

Wax plants are not prone to pests and diseases. Watch out for overwatering. Pests may include nematodes and mealybugs

Mealybugs on Stem
Mealybugs on Stem

In Closing 

The Hoya Krimson Queen is another of my certain recommendations. I have tried to give the most comprehensive guide to make it easy for you to grow this absolutely adorable plant – a beauty that will create a backdrop to any living space. 

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