The exotic Hoya Serpens is a charming plant with long, trailing vines and clusters of felt-like light green flowers.
While not the easiest to grow, prioritizing high humidity and ensuring you water your plant whenever the topsoil gets dry are some of the key ways to ensure your plant grows healthy.
- High humidity is essential, over 60% is a must!
- Water deeply once the top 2 inches of soil is dry;
- Grow indoors for sufficient warmth; choose a bright spot with at least 6 hours of dappled light. Southwest or East-facing windowsills are optimal;
- To encourage blooming, ensure your plant gets sufficient light, and allow your Hoya Serpens to get slightly root bound;
- Fertilize sparingly, use phosphorous-heavy fertilizer to promote flowering. Don’t cut off the peduncles!
Let’s dive into the details.
What is the Hoya Serpens?
Hoya Serpens, sometimes referred to as the Wax Flower Plant, is a rare species belonging to the Hoya genus. This unique plant has succulent-like, round-button leaves that store water.
The Hoya Serpens is known for its felted light-green flowers, which grow in clusters (called umbels) of fragrant blooms. They have a distinct spicy-floral aroma that is most prominent in the evenings. 🙂
How to care for your Hoya Serpens
Hoya Serpens is native to the treetops of the Himalayas. There, the sunlight your plant receives is naturally dappled as taller trees shield your plant from direct light. Mimicking these conditions is your best bet to help your plant thrive.
Place your Hoya Serpens in East or South-West facing windowsills for plenty (at least 6 hours a day) of bright but filtered sunlight. Long periods of intense direct light should be avoided as this is too harsh for your plant, and will lead to leaf scorch.
Though they can survive under partial shade, this is not ideal. Adequate sunlight is essential for your Hoya Serpens to flower and look their best.
Your plant has moderate water needs. Water your Hoya Serpens once you feel, using your fingers, that the top 2 inches (5cm) of soil is dry. It’s important to check this every day or two so that you know once your plant is in need of a drink.
Using this method, watering frequency usually works out to be 2-3 times a week during the prime growing months (spring and summer), and naturally reduces in the fall and winter.
Another tip is to observe your plant for “feedback”. You can tell that your plant is overwatered by monitoring its leaves: soft and droopy foliage is a sign of too much water. In the same way, the slight wrinkling of its leaves indicates it needs more water.
Some plants can tolerate low humidity, but your Hoya Serpens is not one of them. Humidity is a very big deal for this little plant! This Himalayan-native plant needs at the very least 60% of humidity to thrive but does best when this is above 80%.
We’ve found that humidity levels below 60% trigger the plant to stop growing, so it’s really important to have adequate humidity in your home. The best way to do this is to use a humidifier.
Even though Hoya Serpens is native to the Himalayas, the temperature conditions needed for optimal growth are not very cold at all!
Your plant does well in moderate to warm conditions. Temperatures of 68 – 86 degrees F (20-30 degrees C) are perfect. Like many houseplants, fluctuations in temperate are not well-tolerated, so avoid placing your plant near a heater or air vent.
Dips below 50 degrees F (10 degrees C) for extended periods will damage your plant and is asking for trouble. Over extended periods, too-cold temperatures will eventually lead to plant death.
Growth and Flowers
The Hoya Serpens is a fast-growing plant. This Wax Plant can grow rapidly during the months of summer and spring, i.e., the growing season. When mature, the plant measures up to 10 feet tall (3 meters)!
However, its button-like leaves stay quite small, measuring just 0.8 x 0.6 inches (2cm x 1.5cm).
A word of caution though, while Hoya Serpens are prized for their clusters of light-green flowers, they only bloom when fully mature. Unfortunately, this can take up to 7 years! You’ll need to be really patient, or buy a plant that is already established to cut short that waiting time.
When these flowers do emerge, they form umbels of up to 15 flowers each, and are uniquely felt-like (a little fuzzy) in texture. These umbels tend to point downwards like upside-down umbrellas, so it’s a good idea to trail your plant from some height so that flowers cascade down to eye level for everyone to see. They are ideally placed in hanging baskets.
When those clusters of flowers start appearing, you can expect a spicy-floral fragrance to permeate your home in the evenings.
Soil or Growing Medium
Another important care component for the Hoya Serpens is its potting mix. It needs a well-draining, airy mix.
Soils that are too compact or retain too much water spell disaster, as stagnant water tends to suffocate your plant’s roots. This eventually leads to root rot and decay.
We have two growing media to recommend. The first is an airy mix of:
- 1 part commercial potting mix formulated for African Violets; mixed with
- 1 part perlite
This gives the perfect balance of a mix that is well-draining but also one that can retain some moisture to nourish your plant. The African Violet mix itself contains orchid bark and peat moss; while perlite lightens up the mix.
Another option that we’ve found works really well is LECA. Hoya plants in particular love the breathability of this growing medium. Plus, when planted correctly with a “false bottom”, the risk of overwatering and underwatering drastically reduces.
Fertilizers can add nutrients needed for nourishment and growth. But fertilization must be done only if needed! Despite its fast growth rate, Hoya Serpens are considered light feeders.
You may opt for a slow-release fertilizer for an added boost, but less is more in the case of the Hoya Serpens. Use a nitrogen-heavy fertilizer when your plant is young, as nitrogen stimulates foliage growth. When your plant is mature and starts developing peduncles, switch to a phosphorous-heavy fertilizer, as this promotes flowering.
Dilute to half-strength, and apply bi-weekly during the growing season. Hold off during the fall and winter months.
Your Hoya Serpens enjoys being slightly root-bound, so don’t be in a rush to repot. In fact, being slightly root-bound encourages blooming.
Repot when you see roots peeking out from drainage holes, or circling above the surface of the soil. This usually works out to be once every 2 years as your Hoya Serpens grows and their roots begin to fill up the pot.
It is best to repot in the spring or early summer when the plant is actively growing. This gives your plant time to establish into its new pot.
Being from the Hoya genus, the Hoya Serpens is not considered a toxic plant to human beings or animals. However, like all Hoyas, when cut they do secrete a milky-like sap that can irritate your skin.
For this reason, always use gardening gloves when propagating or pruning your plant.
Propagation through Stem Cuttings
Fortunately, your rare and exotic Hoya Serpens can be propagated relatively easily through stem cuttings.
To prepare for propagation, gather a pot filled with potting mix (see Soil section above) alongside some rooting hormone and garden shears.
Here’s what you need to do:
- First, ensure that your garden shears are clean and sterilized. Use 70% isopropyl solution to sterilize your tools.
- Identify a healthy stem of about 4-6 inches long, and cut this stem below the node.
- Remove any leaves from the bottom half of the stem cutting.
- Dip the cut end of the stem into a rooting hormone. This stimulates the growth of healthy roots.
- Plant the stem cutting into potting soil, ensuring that no leaves are buried beneath the soil.
- Place the pot in a warm and bright spot, but one that does not get direct sunlight at all. Filtered, gentle light is best, or partial shade. If you can, place a humidifier next to the pot, and set it to 80% humidity.
- In about 4-6 weeks, you should feel some resistance when you give your stem a very gentle tug. This means that roots have developed.
- There you have it. Treat as you would any other Hoya Serpens!
Some stems of the fast-growing Hoya Serpens can grow rough, jagged, or uneven. It’s good practice to prune off any unwieldy vines to keep your plant looking neat. Also trim away any old, wilted, or yellowing leaves, allowing your plant to focus its energy on new growth.
However, one word of warning: make sure not to trim off the old peduncles. This is because new flowers will emerge from old (re-used!) peduncles.
For this reason, it’s better to allow old flowers to naturally fall off and to keep old peduncles intact. Then, your plant can focus its energy on developing new flowers in the same spot, rather than growing another peduncle in a separate location.
Common Pests and Diseases
Though relatively resistant to pests and diseases, your Hoya Serpens may still occasionally suffer from the occasional issue. The two most likely pests or diseases arise from mealybugs and sooty mold.
Mealybugs are soft-bodied insects that can be identified as white cotton-like masses on leaf axils and undersides. These pests suck on your plant’s sap, depriving them of nutrients. To get rid of mealybugs, use a neem oil solution or insecticidal soap. Here’s our step-by-step guide on identifying and killing mealybugs.
Mealybugs love water-stressed plants, and plants that are high in nitrogen. For this reason, ensure you water your plant properly and don’t overfertilize it, lest you attract these pests!
Sooty mold is a fungus that may arise from a mealybug or aphid infestation. Both aphids and mealybugs secrete a honeydew substance after feeding on your Hoya Serpen’s sap. This honeydew is sweet and sticky, attracting the growth of a black fungus called sooty mold.
Separately, when flowering, your Hoya Serpen’s nectar itself can also attract sooty mold growth. Sooty mold appears as a greyish powdery coating on foliage and flowers.
Unfortunately, according to the Mississippi State University, once established, sooty mold is not easy to remove. Your best course of action is to:
- Soak the affected plants in a mixture of water and detergent. Mix 1 tablespoon of liquid household detergent per gallon of water.
- Use this mixture to also thoroughly spray foliage.
- Wait 15 minutes, then wash off the water and detergent mixture with room temperature water. Ensuring that you water until the water runs clear out of the drainage holes.
- Repeat once every 5 days over the next 4 weeks.
- The sooty mold usually dries and flakes off over time, when controlled in this fashion.
Why is my Hoya Serpens growing so slowly?
Your Hoya Serpen’s growth slows in response to less-than-ideal growing conditions.
Ensure that your plant:
- Has sufficient humidity (at least 60%); or else use a humidifer
- Receives at least 6 hours of dappled light; or else use a grow light
- Is watered properly. Allow for deep watering (until water escapes the drainage hole) when its topsoil is dry, and allow topsoil to dry out between waterings.
- Has an airy, well-draining potting mix; or LECA.
Why is my plant not blooming?
There are a couple of things to consider:
- Is your plant mature? The Hoya Serpens only blooms when mature, and this may take up to 7 years!
- Is your plant receiving enough dappled light (at least 6 hours)?
- Ensure your plant is not too cold or subject to temperature fluctuations. Year-round warmth is the best option for your plant.
- Encourage blooming using a phosphorous-heavy fertilizer, and allow your plant to get slightly root-bound.
Why does my plant have yellow leaves?
Yellowing leaves indicate improper watering or moisture. In the case of Hoya Serpens, this usually results from too little water or too little humidity. Check your soil’s moisture levels to confirm.
Also, check that your plant is using an appropriate potting mix for its needs – check out our Soil section for details on an ideal mix.
Why are my plant’s leaves wilting?
Low humidity levels and underwatering can result in yellowing of leaves and ultimately wilting.
- Check your watering practices – are you checking your plant’s soil moisture every day or two?
- Ensure you water your plant deeply until water escapes from the drainage holes.
- Invest in a humidifier if you live in an arid region. Humidity is essential for Hoya Serpens!
Frequently Asked Questions
Where can I buy Hoya Serpens?
As the Hoya Serpens plant is rare, it’s not easy to find it in the local nursery. You can try getting a Hoya Serpens online from private sellers.
Personally, we like the Etsy platform to look for rare and exotic plants! Do expect to pay a premium for this highly sought-after, rare plant!
Can you grow Hoya Serpens from seeds?
Yes, but given a choice, it is much easier and quicker to propagate Hoya Serpens from stem cuttings.
Hoya Serpens can grow from seeds but needs proper care. The seeds must be sown in semi-dry soil with proper drainage and aeration. Our preference is to leave this to the experts.
What causes the silvery splashes on Hoya Serpens?
The splashes on Hoya Serpens are the result of small pockets of air in the epidermis layer. The splash is actually a type of variegation!
Are coffee grounds good for Hoyas?
There’s been some discussion that adding coffee grounds to potting soil is beneficial for Hoyas. This claim is because some Hoyas like the Hoya Serpens enjoy a slightly-acidic to neutral potting mix.
However, most peat-based potting mixes are already slightly acidic, so we do not see the need for this, especially when using the potting mixes that we have recommended.
Also note that coffee grounds can attract fungi growth due to their being high in organic compounds. Altogether, we caution against adding coffee grounds to your Hoya’s potting mix.
Also, note that some species like Hoya Cumingiana and Hoya Bella prefer neutral to alkaline conditions!
Similar Plants and Varieties
Hoya Serpens Splash
Hoya Serpens Splash features unusual variegation, i.e., blister or reflective variegation. Unlike chimera variegation which results from the lack of chlorophyll, this reflective variegation causes silver spots on the surface of Hoya Serpens Splash leaves.
Hoya Xiaojie 001
Hoya aff. Serpens, also known as Xiaojie 001, is a species of hoya plant that is endemic to China. This plant is a vine with small, heart-shaped leaves. It grows best in moist, shady areas and can be used as an indoor plant. Hoya aff. Serpens is a popular garden plant in China and is listed as a protected species.
Hoya Mathilde is, also known as Hoya Mathilde Splash, is, like the Hoya Serpens, part of the Apocynaceae family and has silver splashes on the leaves. The plant is a hybrid between the Hoya Serpens and popular Hoya Carnosa.
Like many Hoyas, this epiphyte has small leaves and gives off fragrant flowers in the growing season.
The major difference between Hoya Mathilde and Serpens is the size of leaves; the latter has smaller leaves.
Other Hoyas we love
- Hoya Elliptica
- Hoya Clemensorium – a very rare Hoya with long, narrow leaves and intricate dark green patterned veins. A delicate-looking plant.
- Hoya Obovata
- Hoya Imbricata – cup-shaped leaves. a unique plant.
- Hoya Carnosa Compacta, the Hindu Rope Plant
- Hoya Sarawak – an easy-going hoya with round leaves and thin white veins, with pink or fuzzy cream flowers. a slow grower!
- Hoya Nummularioides – another great beginner-level plant with strong honey fragrance
Deborah is a plant enthusiast and founder of Gardening Collective.
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