Hoya plants, often called wax plants, are popular choices for indoor gardeners due to their attractive foliage and unique, often fragrant, flowers. Among the many species, Hoya gracilis and Hoya pubicalyx frequently capture attention. Both are cherished for their vining growth and ease of care, yet they possess distinct characteristics that differentiate them. Understanding these differences can help cultivate them successfully.
Visual Distinctions
The foliage of Hoya gracilis and Hoya pubicalyx presents the most immediate visual cues for differentiation. Hoya gracilis, also known as Hoya memoria, typically features narrow, oblong leaves that are deep green and often speckled with subtle silver variegation. These leaves are relatively small, usually around 2 inches long, and have a slender, elliptical shape. The surface of the leaves is smooth and possesses a waxy, succulent-like texture that can catch the light.
In contrast, Hoya pubicalyx generally displays larger, more elongated, and lanceolate leaves. These leaves are thick, glossy, and can vary in color from deep green to almost black, frequently adorned with prominent silver flecks or splashes. Young leaves of Hoya pubicalyx can emerge with a burgundy hue, especially when exposed to sufficient sunlight, which is due to protective pigments.
The stems of Hoya pubicalyx are vigorous and have a strong climbing habit, capable of reaching impressive lengths of 10-12 feet indoors, making them suitable for trellises or hanging baskets. Hoya gracilis, while also trailing, is described as more low-growing and may not twine as readily on its own, often used in hanging baskets.
Flowering Characteristics
The blooms of these two Hoya species offer another set of distinguishing features. Hoya gracilis produces delicate, star-shaped flowers that appear in clusters, known as umbels. These small flowers typically have pinkish-red corollas and red coronas with a yellow center. They are covered with a delicate fuzz and emit a sweet, often caramel-like fragrance. The flowers usually last for about a week on the plant.
Hoya pubicalyx produces star-shaped flowers that also form in clusters. Flower colors are diverse, ranging from pink and red to nearly black hues. Cultivars like ‘Royal Hawaiian Purple’ can even produce clusters with mixed pink-red and almost black flowers on the same plant. These fragrant blooms are noticeable during evening hours, releasing a sweet scent.
Individual flowers are around 10-18 mm in size. Both species rebloom from the same peduncle, or flower stalk, so these should not be removed after flowering.
Care and Growth Habits
Both Hoya gracilis and Hoya pubicalyx thrive in bright, indirect light. Direct midday sun can scorch their leaves, though Hoya pubicalyx tolerates some direct morning or late afternoon sun. Insufficient light leads to slower, leggier growth and reduced blooming for both.
Both plants are semi-succulent and prefer their soil to dry out between waterings. Overwatering can lead to root rot. A well-draining potting mix, often containing perlite, bark, or orchid bark, is recommended to mimic their natural epiphytic environment and ensure good aeration. Both species appreciate high humidity, ideally 40-70%, though they tolerate slightly drier conditions. Consistent temperatures between 60°F to 85°F (16°C to 29°C) are suitable for both.
Hoya pubicalyx has vigorous, moderately fast growth, producing long vines that can climb or trail. It often sends out leafless tendrils seeking support, which develop leaves once found. Hoya gracilis also trails, but its growth is less aggressive than Hoya pubicalyx. Both benefit from being slightly root-bound to encourage blooming.
Choosing Your Hoya
When selecting between Hoya gracilis and Hoya pubicalyx, consider your aesthetic preferences and available space. If you appreciate smaller, delicate foliage with subtle silver speckling and a low-growing trailing habit, Hoya gracilis is a fitting choice. Its caramel-scented flowers, while less varied in color, offer a distinct aroma.
If you prefer larger, glossier leaves with more pronounced silver variegation and a vigorous vining plant that can climb or trail extensively, Hoya pubicalyx is a strong contender. Its wide range of flower colors, from pink to dark burgundy, and evening fragrance, are appealing. Both plants share similar light, watering, and humidity needs. The best choice depends on the visual impact and available space.