The Hoya genus, often called wax plants, has captured the attention of plant enthusiasts worldwide, largely due to the diversity in its foliage. Two cultivars, the ‘Nova Ghost’ and the ‘Grey Ghost’, are particularly sought after for their striking, near-solid silver leaves, creating a visual effect that seems to defy typical plant coloring. The similar names and highly prized silver foliage often lead to confusion among collectors. This comparison aims to clarify the specific differences in appearance, origin, and cultivation that set these two rare Hoya carnosa forms apart.
Distinctive Visual Characteristics
The most reliable way to differentiate these two collector plants is by examining the morphology and texture of their leaves. The ‘Nova Ghost’ typically presents with a more saturated, almost satiny silver or white appearance, especially on new growth. Its leaves are generally shorter and exhibit a more pronounced veining structure that is often visible even beneath the dense silver layer. This prominent venation contributes to a slightly more textured feel.
In contrast, the ‘Grey Ghost’ tends to display a lighter, often described as a dusty or chalky grey-silver coloration with a matte finish. This cultivar’s leaves are usually narrower and longer, sometimes possessing a more elongated or irregular shape. The veining is noticeably less prominent, with often only the midrib being clearly discernible. Furthermore, the ‘Grey Ghost’ leaves are reported to be thicker and feel rougher to the touch than those of the ‘Nova Ghost’.
The silvering on both plants is a form of variegation where the chlorophyll layer is partially obscured, but the pattern differs subtly. The ‘Nova Ghost’ often achieves a more uniform, solid silver “splash” across the entire leaf surface. The ‘Grey Ghost’ may show slightly more mottling or soft marbling within the grey-silver areas. These subtle differences in color saturation and texture are the primary visual cues for accurate identification.
Origin and Naming History
Both ‘Nova Ghost’ and ‘Grey Ghost’ are recognized as distinct cultivars of the common Hoya carnosa, a species native to Eastern Asia and Australia. The ‘Grey Ghost’ has a longer history in cultivation, having been introduced by B.L. Cobia in the 1970s. This early introduction established the name “Grey Ghost” for a specific, slow-growing, grey-leaved form of the species.
The ‘Nova Ghost’ is a more recent introduction, originating as a spontaneous mutation or “sport” from another cultivar, Hoya carnosa ‘Argentea Princess’. This means the ‘Nova Ghost’ is a stable reversion, losing the typical variegation of its parent to gain the solid silver coloring. The similar descriptive names, both using the term “Ghost” to reference the pale, silver foliage, are the main source of confusion in the plant market.
Because both names describe a silver-leaved Hoya carnosa, many sellers and collectors use the terms inconsistently. However, understanding their distinct origins—one an older, named selection and the other a sport from a specific variegated line—reinforces their separate identities.
Comparative Cultivation Requirements
While the general care for all Hoya species is similar, the ‘Nova Ghost’ and ‘Grey Ghost’ exhibit notable differences in growth habit and stability. The ‘Nova Ghost’ is generally reported to be a much faster and more vigorous grower than its counterpart. This characteristic makes it a less temperamental plant for the average grower, establishing roots and producing new vines more readily.
The ‘Grey Ghost’, conversely, is notoriously slow to grow, often sitting dormant for long periods before showing new development. This slower growth rate requires more patience and consistent conditions from the cultivator. Furthermore, the ‘Grey Ghost’ is sometimes observed to be less stable, with a higher potential to revert back to producing plain green Hoya carnosa leaves if not given optimal conditions.
For both silver-leaved cultivars, light intensity is paramount because the silver coloring is a form of variegation. Both plants require bright, indirect light to encourage the maximum expression of the silver “ghosting” effect. The heavily silvered leaves lack the chlorophyll of green leaves, meaning they are less efficient at photosynthesis. Therefore, insufficient light will lead to a loss of the silver coloration, especially in the ‘Grey Ghost’, or severely stunted growth. Growers should aim for temperatures between 60 and 85 degrees Fahrenheit, and moderate humidity supports the development of new foliage.