Hoya vs Orchid:  8 Facts Compared

Hoyas are often confused with orchids.  Are hoyas orchids?

Hoyas and orchids are not related and have different vining structures and blooming features.  But the plant care in terms of the light, temperature, and fertilizer requirement is very similar.

In this article, we will show you all the differences and similarities.

1. Classification

In terms of their scientific classification, hoyas and orchids are not at all related.

Hoya (Hoya Carnosa) is a genus from the Dogbane (Apocynaceae) family.  The Hoya genus comprises some 500 species of hoyas.

On the other hand, orchid (Orchidaceae) is a family itself containing several genera such as Phalaenopsis, Cattleya, Vanda, with over 27000 orchid species.  As such, there are significantly more orchids than hoyas.

Another difference is that Hoyas are found mostly in the tropical climate, such as that in India, Vietnam, Thailand in Southeast Asia, in Australia, and the Pacific Islands (e.g. New Guinea) while orchids can be found in a wide range of climates, from tropical to temperate regions all over the world, except Antarctica.

2. Appearance

Waxy leaves

Hoyas (also called “wax plants”) are often confused as orchids because they both have thick, evergreen leaves with a thick cuticle covered in wax. 

This is a characteristic of many tropical plants native to regions with lots of sunlight or a dry climate for water preservation and disease prevention. 

Leaf shape and size

Apart from both having waxy leaves, hoyas and orchids have different leaf shapes and sizes.

Most hoyas have round or oblong-shaped leaves (e.g Hoya obovata).  Some have heart-shaped leaves (Hoya kerrii) and others like Hoya shepherdii have elongated leaves like runner beans.

Different Hoya species have different leaf sizes, ranging from ¼ inch (5 mm) in length (for Hoya engleriana) to 10 inches (over 25 cm) in length (for Hoya latifolia).

Vining structures

Both hoyas and orchids have structures that can attach to or climb a surface, but their vining structures are different.

For hoyas, the vining structures are stems that can generally extend up to 2 – 4 feet (0.6 – 1.2 meters) long to climb up trees and attach to surfaces. 

For orchids, the species that are epiphytic have long aerial roots that can climb on surfaces.  Their stems are non-vining. Some orchids like Cattleya and Dendrobium have thickened stems called pseudobulbs that act as water storage structures.

Hoya kerrii have thick waxy, heart-shaped leaves on long epiphytic stems // Tangopaso, CC BY-SA 3.0, via Wikimedia Commons

3. Blooming

Hoyas bloom in the summer or spring, with clusters of star-shaped flowers that last for a couple of weeks. In contrast, orchids bloom at different seasons depending on the species, and the flowers remain on the plant for longer durations than Hoyas.

Hoya

Hoya species bloom when they reach maturity which takes four to five years at least. The plants flower once a year in summer or spring depending on the species.

All Hoyas produce umbels of 10 to 40 star-shaped flowers. The blooms remain on the plant for a 1 to 2 weeks before they fall off, leaving the spur (or peduncle) behind which will produce new flowers the following year.

The flowers consist of five triangular waxy petals arranged in the shape of a 5-point star. In the center of each flower is a smaller star-shaped corona in a different color from the petals

Although hoya flowers all have a five-star shape, the colors vary between species. The typical colors are pink, white, purple, red, and yellow.

Here’s a list of some popular Hoya species and their flower colors:

• Hoya carnosa – pale pink petals with reddish center
• Hoya kerrii– white with purplish-brown center
• Hoya australis – white petals with reddish centers
• Hoya cumigiana – Yellow with maroon centers
• Hoya obovata – white/pale pink with purple centers

Most Hoya species are fragrant, and some more so than others. For instance, Hoya carnosa produces a strong sweet smell, while the Hoya obovata is only faintly fragrant.

Orchids

Orchids bloom when they are at least three years old, and some can be as old as six years before producing flowers. When they bloom, they produce flowers that can last between 2 to 5 months.

Most orchid species bloom once a year, but many Vanda species can bloom 2 to 3 times a year.

Unlike Hoya, different orchid species bloom in different seasons. Most species bloom in fall and winter, triggered by a drop of temperature down to 64 Fahrenheit (or 18 Celcius) for 2-4 weeks (link).

The flowers have three petals and three sepals. The sepals and two of the petals are often similar in shape and color, but the third petal, called a labellum, is markedly different, folding inward, and is often a different color from the rest of the flower.

Typical flower colors include white, yellow, pink, purple, red, and orange. Here’s a list of popular orchid genera and their colors

• Phalaenopsis – white, pink, yellow
• Vanda – purple and magenta
• Dendrobium– white, green, yellow, pink
• Cattleya – yellow, white, pink, purple
• Cymbidium – white, maroon, brown, pink
• Paphiopedilum – yellow, white, purple,
• Oncidium – red, white, pink, yellow
• Bulbophyllum – Orange, yellow, purple, pink
• Miltoniopsis – red, white, yellow, maroon, purple

Some species of Phalaenopsis and Cattleyas are fragrant while others have foul odors like the Bulbophyllum orchids.

4. Light requirement

Hoyas and orchids generally prefer bright indirect sunlight instead of direct light to grow properly. This kind of light can be obtained by an east- or west- facing window.

Too much light, such as the direct light from the sun or by a south-facing window can burn the leaves, producing discolored patches on the leaves.

Hoya

The vast majority of hoya plants require bright indirect light with medium to high light intensities between 300 to 400 umol/m2/s (1500 to 2000 foot candles) for about ten hours a day (Osbourne et al, n.d).

Orchids

The optimal light intensity for orchids is bright indirect light ranging from 100 to 500 umol/m2/s. Orchid species with succulent-like leaves often prefer bright light, while thin-leaved orchids prefer low light. 

• Low-light orchids (100 to 135 umol/m2/s):  Phalaenopsis, Paphiopedilum, and jewel orchids
• Medium-light orchids (around 300 umol/m2/s):  Dendrobium, Oncidium, and Miltoniopsis.
• Strong-light orchids (300 to 500 umol/m2/s):  Cattleya and Vanda

Orchids require 14 to 16 hours of light per day in the summer and spring when they are actively growing. In winter, they need less light, about 10 to 12 hours per day.

5. Moisture requirement

Both hoyas and orchids can easily suffer from overwatering, because their leaves and stems can store water, allowing them go for days without being watered.

Hoya and epiphytic orchids prefer to have their roots dry out before being watered again because their roots can easily rot when the growing substrate is waterlogged.  They are also able to store water in their thick leaves and stems (or pseudobulbs for orchids).

They require more water in the summer and spring than in the winter when it is cold and the plant is not actively growing. On average, hoyas and orchids can survive with watering once a week in the summer and once in two weeks in winter.

But these are estimates, the actual moisture requirements depend on the plant, the ambient humidity, and the temperature. For instance, indoor plants may need more water in winter than in summer. This is because of the increased central heating that causes the plant to dry out faster than normal.

6. Growing substrate

Both orchids and Hoya are natural epiphytes with roots that are exposed to the air rather than buried in the soil. As such, they both require substrates that allow air circulation around the roots and quick drainage of irrigation water.

As epiphytes, hoya and orchids prefer substrates that are light and airy to allow proper air circulation around the roots and good water drainage.

The nature of the substrate, whether soil based or not, does not matter, as long as it has good aeration and drainage.

A good substrate for hoya is a mix that contains potting soil, perlite, and vermiculite in equal parts. The perlite and vermiculite improve the ventilation and drainage in the container, while the potting soil holds water and covers the roots.

Orchid substrates are usually made of non-soil-based materials like fir bark (link), charcoal, perlite, vermiculite, lava rocks, sphagnum moss, and coconut coir. These materials are quickly draining and allow air circulation. They can be used alone, or combined with another material. A combination of sphagnum moss and lava rock is a good substrate for most orchid species.

7. Temperature requirement

Hoyas and orchids have similar temperature requirements, as most are tropical/subtropical plants. They grow better in warmer temperatures that mimic their native tropical environments.

Hoya

The average optimal temperature for Hoya species is between 65 to 85 F (18.3 to 29.4 C). However, certain species may prefer temperatures that are either cooler or warmer than the average.

Orchids

The average day temperature for orchids is generally between 70 to 77 F (21 to 24 C), depending on the species.

• “Cool orchids” require day temperatures between 60 to 70 F (15.5 to 21 C) and night temperatures between 50 to 55 F (10 to 13 C). Examples include dendrobium species.

• “Intermediate orchids” require day temperatures between 70 to 80 F (21 to 26.6 C) and night temperatures between 55 to 65 F (13 to 18.3 C). Examples include Bulbophyllum and Miltoniopsis species.

• “Warm-growing orchids” require day temperatures between 80 to 90 F (26.6 to 32.2) and night temperatures between 65 to 70 F (13 to 21 C). Examples include Paphiopedilum and Phalaenopsis species.

Besides day temperature, night temperature is also important for orchids, as the difference between day and night temperatures is what triggers flower production.

8. Fertilizer requirement

Both hoya and orchids require a regular but light dosage of fertilizer for proper growth. Hoya species require high nitrogen fertilizers, because of their greater foliage, but orchids don’t need this.

Hoya

Hoya plants are foliage plants, and as such, they require fertilizers with higher nitrogen content to encourage leaf growth. A fertilizer with a 2:1:2 or 3:1:2 ratio is sufficient.

However, In the months before the plant flowers, the high-nitrogen fertilizer can be replaced with a balanced fertilizer for producing flowers.

Hoya plants can be fed once or twice per month in the summer and spring when the plant is actively growing. But during winter the plant does not require fertilizer as it is mostly dormant.

It’s best to use a light dosage of fertilizer for Hoya, as the roots are sensitive and can get burned if the dosage is too strong.

Orchids

The best fertilizer for orchids contains nitrates instead of urea since they don’t grow in soils where there are microbes to convert the urea to useful nitrogen.

Unlike Hoya plants, orchids do not need high nitrogen fertilizer, and regular balanced fertilizers will work sufficiently.

They prefer a weak dose of fertilizer applied at intervals, rather than one strong dose applied all at once, as this can burn the sensitive roots.

Most gardeners adopt the “Weakly weekly” approach, diluting the fertilizer to a quarter of its strength, and applying it to the plant each week during the growing period.

Fertilizer application is done during the growth cycle of the orchid which is usually in the spring and summer. During winter, most orchids are dormant and do not require fertilizer.

References

Orchids and How They Grow. (2004, April 1). Brooklyn Botanic Garden.

Fay, M. F. (2018, June 5). Orchid conservation: how can we meet the challenges in the twenty-first century? – Botanical Studies. SpringerOpen.

Osbourne, L., Henley, R. W., & Chase, A. R. (n.d.). Wax Plant (Hoya) Production Guide. University of Florida.

American Orchid Society. (n.d.). Orchid Temperature Ranges. AOS.org.