Last updated on August 25th, 2023 at 12:07 pm
Hoya carnosa rubra, commonly known as the rubra wax plant, is a tropical plant species in the genus Hoya that grows in equatorial regions worldwide.
When placed in the right location, growing Hoya carnosa rubra (also known as the Rubra Wax Plant) can be an attractive addition to any home or office environment.
As with any other houseplant, you should research what hoya carnosa rubra needs in order to thrive and avoid common mistakes that can keep your plant from living its best life possible. In this article, we’ll discuss how to care for hoya carnosa rubra.
First, however, let’s take a look at what this plant looks like and what it needs to grow well in your home or office setting.
Origin and distribution
Hoya Carnosa rubra originates from Northern India and Bangladesh, where it was discovered in 1874 by British botanist John Scott Rizzieri.
It is cultivated in other parts of India, Nepal, Sri Lanka, Mauritius, Java, and Malaysia for its ornamental value.
The plant’s name derives from this discovery, as the Latin carnosa means fleshy or succulent, and rubra means red.2 As such, the name translates to a red fleshy-leaved wax plant in English.
It was introduced into Europe by British colonists in 1846 and has naturalized over much of its range. It was named after John Gilbert Baker who collected plants on Mauritius from 1843 to 1845.
During his collecting trip, he discovered a very large number of plants that had previously not been known to science. He sent them back to England where they were described and published by William Hooker in Icones Plantarum between 1848-1862.
Hoya carnosa rubra propagation
Hoya carnosa rubra is easier to propagate through cuttings than seeds. The Rubra variety is also commonly propagated through leaf-cuttings. Use a sterile blade to make a clean cut just below where a leaf meets its stem. From there, place your cutting in some water, using only water until roots begin to sprout.
Once you see new growth, it’s time to transfer it into the soil. When growing Hoya carnosa in soil, use a well-draining potting mix and keep it moist at all times. Like most plants, Hoya carnosa prefers bright indirect light and humidity. If you can create an environment that mimics these conditions for your plant, it will grow best!
Hoya carnosa rubra care information
Hoya carnosa rubra care is easy. Keep your wax plant away from drafts or air conditioning vents, which can also cause leaf discoloration and damage to leaves. If you notice black spots on your hoya’s leaves, it may be a sign of too much fertilizer.
Also, keep in mind that your hoya will need a rest period during the winter months; cut back on watering and allow the soil to dry out between waterings.
Light requirement
Hoya carnosa rubra prefers bright indirect sunlight and should be brought indoors when temperatures dip below 55 degrees Fahrenheit. Even in ideal conditions, keep your plant on a bright windowsill or under fluorescent lights. Failing to provide adequate light will result in long, spindly stems that lack color and have fewer flowers.
Soil/potting mix
These plants prefer well-draining soil, so don’t add peat moss or compost to your potting mix. They do best in loose, well-aerated soil that allows their roots to breathe easily.
Use coarse sand and perlite or pumice as an additive to promote good drainage.
Avoid using garden soil if possible because it can compact around their delicate root systems. When planting, bury them just under the surface of your potting mix; they like to be slightly buried in order for their stems to grow upright.
Watering
If you’re caring for your Hoya Carnosa rubra indoors, you need to water it regularly. In fact, most Hoyas need to be watered every two days or so. The key is to let them dry out between watering sessions so that their soil doesn’t remain soggy and mold-prone.
A good general rule of thumb is to avoid getting water on their leaves at all costs. To water your plant, soak its pot in a sink full of room temperature water for about 15 minutes before draining away any excess.
Then wait until the top 2 inches of soil feel dry before giving it another drink.
Fertilizer
Fertilizing hoya carnosa rubra is a must to keep it looking its best and growing like mad. In fact, if you haven’t fertilized your wax plant in a while, it probably looks very sad by now. If that’s true for your plant, then fertilize immediately.
How often you fertilize will depend on where you live and what type of soil you have.
For example, plants grown in water can be fertilized more frequently than those grown in dry soil. For dry-soil plants, once every two months should be sufficient; for water-grown plants, once every month should do it.
You can use an all-purpose fertilizer or one specifically formulated for orchids or bromeliads, whatever works best for your plant.
Temperature
The wax plant prefers warm temperatures and can be damaged by temperatures below 50°F. If you want to keep your wax plant as a houseplant, try to keep it within a temperature range of 70-80 degrees Fahrenheit. Be sure to avoid drafty areas or placing it near air conditioning vents that may blow cold air on it.
Humidity
In order to grow well, Hoya carnosa rubra likes high humidity but not direct sunlight. Make sure you know where your wax plant is going to go in your home before you bring it home so that you can give it a good spot to live.
If it doesn’t have enough humidity, its leaves will wrinkle and fall off. To help increase its level of humidity, mist its leaves occasionally with lukewarm water.
The ideal humidity range is between 40 and 80 percent. If you’re having trouble getting your plant to stay at a comfortable level of humidity, use a humidifier or place it on a tray of pebbles that have been filled with water. Be sure to change out the water regularly so that it doesn’t become stagnant.
Pruning
Hoya carnosa rubra is a tropical houseplant that tends to grow very tall and leggy if not pruned regularly. When it gets too tall, cut off the bottom leaves to promote branching.
You may also want to remove new leaves in summer since Hoya is evergreen (unlike some other tropical plants). Otherwise, trim away flowers after they’ve bloomed and dried up—this encourages more flower production.
When to repot
Like most succulents, Hoya carnosa rubra needs to be repotted every two years. So, if you purchase your wax plant in a container, you’ll need to transfer it into a larger pot before it starts growing out of its old home. If your plant is already growing out of its pot, then wait until next year and repot it.
You can do so by cutting off any leaves that are touching soil or other plants and removing excess soil from around the roots. Then place your plant in a clean container with fresh potting soil that drains well. Make sure not to overwater!
Also, make sure not to put your wax plant too close to direct sunlight as it will dry out quickly.
Dormancy/Winter rest
Hoya carnosa rubra has a long winter dormancy and should be kept cool at 40-45 degrees. If you live in an area that is prone to cold temperatures, it is best to protect your plants from freezing by moving them into pots and storing them in an unheated space like a garage or cellar.
They can also be brought indoors if they are protected from bright light and kept near a sunny window. In addition, make sure they are watered only sparingly during their dormancy period as they need very little water while dormant.
When bringing your plant back outside again after its winter rest, keep it out of direct sunlight for about two weeks so that it can adjust to its new environment before being placed back under full sun exposure.
Flower & fragrance
Hoya carnosa rubra is known for its beautiful foliage and fragrant flowers. The leaves are shiny green with red margins and thin, reddish-brown edges. If you look closely, you’ll see that they are actually composed of many tiny leaflets called pinnate leaves.
The stems bear clusters of yellow flowers that smell just like those of orange blossom, but they also emit a powerful fragrance when rubbed or handled roughly.
Growth rate
This plant grows steadily and quickly in ideal conditions and can be pruned to keep at whatever size you want. It will likely double in size every six months or so; when I started it, it was around four inches tall, and now is over a foot.
You can trim the stem if it begins to take over other plants too much; just leave a little bit of stem, since they easily sprout new leaves from their base.
Toxicity
Hoya carnosa rubra, otherwise known as a wax plant, is non-toxic to humans and pets. The leaves have been used to protect against insect stings and can even be eaten by goats! However, make sure that you don’t let any skin come in contact with its thorns.
USDA hardiness zones
Hoya carnosa rubra thrives best in USDA hardiness zones 10 through 12. In colder climates, it can be grown as a houseplant.
Pests and diseases
The major problem with hoyas is their susceptibility to pests and diseases. Mealybugs, mites, aphids, scale insects, and thrips can be problematic on hoyas. It is also possible that your plant could be attacked by two or more different kinds of pests at once!
Conclusion
Rubra wax plant, otherwise known as Hoya carnosa rubra, is a houseplant that is easy to maintain. It doesn’t require any special sunlight or fertilizer for good growth and can be grown indoors.
It does best when it’s directly in front of a window so it can soak up some of those rays for optimum color and vigor. A little pruning once a year will also help maintain good shape, although it isn’t necessary if you keep an eye on it.
