Hoya rubra, commonly known as the ‘Rubra’ wax plant, is a captivating houseplant. It is cherished for its striking variegated foliage, making it a popular choice for indoor gardeners due to its appealing appearance and manageable care. Its trailing vines and unique leaf coloration add visual interest to any home.
Identifying Hoya Rubra
Hoya rubra is distinguished by its vibrant, multi-colored leaves, featuring shades of green, white, cream, and significant pink or red tinges. New growth often emerges with particularly intense pink or red hues, transitioning to creamy variegation as the leaves mature. This variety has glossy, pointy leaves that are somewhat wider than some other Hoya types.
Hoya rubra is sometimes confused with ‘Krimson Princess’ or ‘Krimson Queen’. ‘Krimson Princess’ was originally a trade designation for Hoya carnosa ‘Rubra’. ‘Krimson Queen’ differs by having its white or pink variegation along the outer leaf edges, rather than primarily in the center as seen in Hoya rubra.
Caring for Hoya Rubra
Light
Hoya rubra thrives in bright, indirect light, ideally near an east or south-facing window to avoid harsh afternoon sun. Adequate light enhances the vibrant pink and red variegation; insufficient light can lead to slower growth and faded coloration.
Water
Hoya rubra prefers its soil to dry out thoroughly between waterings. Overwatering can lead to root rot, a common issue for Hoyas, as their succulent leaves store water. Check soil moisture by inserting a finger about two inches deep; if it feels dry, the plant is ready for water. When watering, saturate the soil completely until water drains from the bottom, then empty any excess from the drainage tray.
Soil
Hoya rubra requires a well-draining, airy potting mix to prevent waterlogging and promote healthy root development. A suitable mix often includes components like orchid bark, perlite, and potting soil. Some growers also recommend adding coco chips, pumice, or horticultural charcoal to enhance drainage and aeration. This type of chunky, porous substrate mimics the plant’s natural epiphytic growing conditions.
Temperature and Humidity
Hoya rubra prefers warm indoor temperatures, 60-80°F (15-27°C). Protect the plant from sudden temperature fluctuations and cold drafts, especially during cooler months. As a tropical plant, Hoya rubra requires moderate to high humidity levels, ideally between 40% and 70%. To increase humidity, mist the leaves occasionally, place the pot on a pebble tray, or use a room humidifier.
Fertilizer
During its active growing season in spring and summer, Hoya rubra benefits from regular fertilization. Apply a balanced, water-soluble fertilizer, diluted to half strength, every 3 to 4 weeks. Reduce or stop fertilization during fall and winter when the plant’s growth naturally slows.
Propagating Hoya Rubra
Hoya rubra is propagated through stem cuttings. The best time to take cuttings is during the active growing season in spring and summer. Select a healthy stem segment with at least one or two leaf nodes. Make a clean cut below a node, ensuring the cutting is 4 to 6 inches long, and remove any leaves from the lowest part that would be submerged.
Cuttings can be rooted in water or a well-draining potting mix. For water rooting, place the cutting in a container with water, ensuring the node is submerged but leaves remain above the waterline. For soil propagation, insert the cutting into a light, airy medium like perlite or a succulent mix. Roots begin to form within a few weeks, after which the new plant can be potted.
Common Challenges with Hoya Rubra
A lack of vibrant variegation is a common issue for Hoya rubra. This often occurs when the plant does not receive sufficient bright, indirect light, causing the distinctive pink and red hues to fade. Increasing light exposure can help restore leaf coloration.
Leaf yellowing or browning is another common concern, frequently linked to improper watering practices. Overwatering can lead to soft, mushy yellow leaves due to root rot, while underwatering may cause leaves to become dry, crispy, and yellow, sometimes with a wrinkled appearance. Adjusting the watering schedule to allow the soil to dry out between waterings is important to address these symptoms. Additionally, cold drafts or extremely low temperatures can also contribute to yellowing leaves.
Slow or leggy growth indicates insufficient light or nutrients. Provide more bright, indirect light and adhere to a regular fertilization schedule during the growing season for fuller, more vigorous growth. Common pests include mealybugs and spider mites. Mealybugs appear as small, white, cottony masses, while spider mites cause fine webbing and tiny spots. Treating mealybugs can involve wiping them with rubbing alcohol or using insecticidal soap. For spider mites, neem oil or insecticidal soap are effective.