Hoya care

The Hoya plant, also known as the porcelain flower or wax plant, is a genus in the dogbane family (Asclepiadaceae). It is native to Southeast Asia (from India eastward to southern China and areas further south), Australia, and Polynesia. The botanist Robert Brown named it after his fellow botanist, Thomas Hoy.

It originates from the tropical and subtropical regions of Asia, as well as the Australian and Pacific islands. It is native primarily to areas such as India, China, Indonesia, Malaysia, Thailand, the Philippines, and New Guinea. It was introduced to Europe and the United States in the 19th century.

Introduction to Hoya

Hoya plants are among the most beautiful houseplants. Nevertheless, only a few of the over 200 existing varieties can be found on flower shop shelves. The most well-known species, which even our grandmothers grew as a blooming indoor decoration, is Hoya carnosa. It is a fast-growing, climbing variety, with decorative foliage even when not flowering. Its thick, glossy leaves range from dark to lighter green depending on light conditions and are often adorned with irregular light spots.

Its star-shaped flowers, which bloom from spring to autumn, cluster in umbels and truly look as if made from wax or porcelain. The pale pink flowers have a sweet fragrance. Caution: the nectar that drips from the flowers can stain upholstery and furniture, and the drops can promote sooty mold on floors. It produces long, trailing or climbing stems that can be trained on a support.

The stems of Hoya plant can reach up to 10 feet (3 meters) in length, so it's best to train them on wire, moss poles, or trellises. The leaves are coated with a tough wax layer. In summer, you can place it outside in a shady spot in the garden or on the terrace; in winter, an unheated glass veranda or entryway is ideal.

Other names for the wax plant (Hoya) include porcelain flower, wax vine, Our Lady’s tears, Christ’s tears, or crown flower.

Hoya Care

Hoya care in brief: it requires a lot of light but must be protected from direct, harsh sunlight. In spring and summer, it needs a consistent temperature of 64 - 77 °F (18 - 25 °C), while in winter it prefers slightly cooler conditions. It has moderate water needs; allow the soil to dry out more between waterings. From spring to fall, water it with liquid fertilizer every 2 - 4 weeks.

Light Requirements for Hoya

Hoya plants need a bright spot year-round, even in winter; you can place them on a windowsill, but avoid direct, harsh sunlight. If the plant receives too little light, it will grow long, leafless stems and will not bloom in dark locations.

Strong, filtered light encourages both growth and flowering. Direct sunlight can scorch the leaves, especially if exposed for extended periods.

Temperature Requirements for Hoya

Due to its tropical origin, Hoya plant prefers consistent warmth, around 64 - 77 °F (18 - 25 °C), although it tolerates higher temperatures well. In winter, it requires at least 59 °F (15 °C). In cooler conditions, the flowers may drop off.

Temperatures below 50 °F (10 °C) can harm the plant. Avoid placing it in cold drafts or near air conditioners.

Watering needs for Hoya

Proper watering is crucial: even in summer, avoid overwatering, and during winter, keep watering to a minimum, as too much water can easily kill the plant.

In such cases, the leaves begin to decay and wilt as if suffering from drought, but by then the roots are often already mostly rotted, leaving little hope for survival.

At that point, you can try removing the plant from its container, clean off the soil, cut away the rotten roots up to the healthy parts, and replant it in a smaller pot with soil containing plenty of river sand. Then place it in a warmer spot and water very cautiously. However, this method may still not save the plant.

Using loose, well-draining soil helps reduce the risk of root damage from standing water in the pot. Never let water accumulate in the saucer! Let the soil dry out almost completely between waterings.

Mist the plant regularly when it is not blooming. Avoid misting during the flowering period. While not particularly demanding and tolerant of dry indoor air, it thrives even better in higher humidity (50 - 70%).

Fertilizing Hoya plant

Hoya plant does not have high nutrient demands, but during the growing season (spring to autumn), it benefits from being watered with a liquid fertilizer every two to four weeks. Use general-purpose houseplant fertilizer. Do not fertilize at all in late autumn or during the winter months.

A balanced fertilizer containing roughly equal parts nitrogen, phosphorus, and potassium is suitable. From the start of flowering and throughout the blooming period, choose a fertilizer with higher phosphorus content to promote flower formation.

Feeding Hoya plant biweekly with a potassium-rich fertilizer from spring to autumn is ideal. Avoid overfertilizing, as it can hinder flowering or cause the plant to stop blooming altogether.

A lack of flowering can also be caused by nutrient deficiency or insufficient light. If the plant is placed in a pot that is too large, it may also weaken or stop blooming.

Do not use high-nitrogen fertilizers—too much nitrogen leads to lack of flowering. If you also grow orchids, you can reuse leftover bathwater mixed with Vitaflóra Orchid fertilizer to water your Hoya plant.

Planting and Repotting Hoya

The best time to repot Hoya is in spring, especially if you notice slowed or halted shoot growth, outgrown pots, depleted soil, or exhausted nutrients. A loose, well-draining soil is recommended, such as a cactus or orchid potting mix.

Suitable options include Florasca B or similar peat-based potting soil, but good quality garden soil mixed with peat is also appropriate. Since Hoya grows very slowly, repotting every 3–4 years is usually sufficient. However, if it outgrows its pot faster, don’t wait to repot.

Wintering Hoya

Hoya is usually kept as a houseplant, so technically it doesn’t require overwintering, but some seasonal care is necessary. During winter, it prefers cooler temperatures around 64 - 68 °F (18 - 20 °C).

Keep it in a bright spot if possible, as winter light levels are low and it needs natural daylight. Reduce watering significantly—only water when the soil is nearly dry. Do not fertilize during this time.

Pruning and Shaping Hoya

Hoya doesn’t require regular pruning as it grows slowly and naturally retains its form. However, if pruning is needed, avoid cutting off old flower stems, as it often blooms again on the same shoots.

Prune only if the plant becomes too large, or if any shoots are dead, damaged, or diseased. You can also prune to shape it if it's growing in an unwanted direction.

Hoya Blooming and Flowers

Hoya typically blooms from spring through fall, but you’ll need patience—it often blooms only on older, established plants, just when you least expect it. To encourage blooming, keep the plant cooler and drier for a few weeks (around 64 - 68 °F / 18 - 20 °C, depending on the variety).

A drop in nighttime temperatures can also stimulate blooming. After blooming, the flower stem doesn't die back—new buds often form at its tip. If you cut it off, you’ll disrupt future blooming. The next year’s flowers will grow from that same stem.

Do not remove wilted flowers. Once buds appear, avoid moving or rotating the plant. If lighting conditions change and the plant receives light from a different angle, it may drop its buds.

Propagating Hoya

Propagation is easiest and most reliable through leaf or stem cuttings. Air layering is another method worth trying, as it doesn’t require removing the shoot from the parent plant right away.

Propagating Hoya from Cuttings

Propagate Hoya plant from leaf or stem cuttings from spring to early summer. Cut a healthy side shoot, remove the lower leaves so only one leaf pair remains, and plant the cutting into moist sand and peat-based medium.

Leave about 0.8 inches (2 cm) of stem below the leaf pair to be buried in the soil for rooting, and keep about 0.4 inches (1 cm) above to prevent damage to the leaf node buds, which will grow into new shoots.

Cover the pot with clear, perforated plastic (or a glass dome) to create high humidity and promote rooting.

Properly prepared cuttings root well even in water if placed in a warm, bright location. The soil used for transplanting should contain at least one-third sand to ensure good drainage.

Rooting Hoya Cuttings in Water

To root Hoya in water, place only the node section of the cutting in water. Change the water every 3–5 days. Place the cutting in a bright but shaded area. Roots typically develop in 2–4 weeks.

Propagatin Hoya by Air Layering

For air layering, choose a strong, healthy shoot. Make a shallow incision at a node. Cover the cut with moist sphagnum moss, then wrap it in plastic and secure it with string or a rubber band.

Keep the moss consistently moist. After a few weeks, check for root development. Once roots have formed, cut the shoot from the mother plant and pot it up.

Hoya Diseases, Pests and Causes of Decline

Hoya is relatively resistant to diseases. During winter, pests such as aphids and mites may appear. Improper care can also lead to issues. If planted in infected soil, nematodes may attack the roots.

Hoya Diseases

In case of fungal leaf spot, brown or black spots appear on the leaves and may enlarge over time. It is caused by high humidity, poor ventilation, and moisture lingering on the leaves. Remove the infected parts and use a fungicide.

Bacterial leaf spot appears as wet, yellowish patches on the leaves and spreads quickly. It is also caused by high humidity and moisture remaining on the foliage. Remove the affected parts and ensure better air circulation around the plant.

Hoya Pests

Hoya is a preferred host for the root-knot nematode. These form cluster-like swellings or galls on the roots. Symptoms include stunted growth, yellowing leaves, and drying flower clusters. They are usually spread through contaminated soil. Nematocide can be used to treat it.

Scale insects, aphids, and mealybugs mostly cause damage during winter when the plant is kept too warm. Scale insects appear as tiny brown or rusty bumps on the leaves and stems. Aphids are small green, black, or brown insects and often leave behind sticky honeydew. Mealybugs appear as white, cottony clusters on leaves and stem joints. Their presence causes yellowing and drying of leaves. Start by wiping the plant with soapy water, which may need to be repeated. If ineffective, use insecticides or neem oil spray.

Spider mites prefer warm, dry environments. They are hard to see, but fine webbing on the leaves indicates their presence. If they multiply, affected leaves will discolor and fall off. Treat infestations with a miticide.

Environmental Factors and Improper Care of Hoya

Lack of blooming can be due to nutrient deficiency, frequent relocation, poor lighting, or cutting back post-blooming shoots. Avoid repotting annually or changing its location unnecessarily.

In overly dry air, flower buds may yellow and drop. Early signs include dry, browning leaf edges.

Overwatering results in yellowing, wilting leaves and may lead to root rot.

Insufficient light can prevent blooming, cause leggy growth, and lead to pale or yellowish foliage.

Direct sunlight can scorch the leaves, leaving brown, burned patches.

Is Hoya Toxic?

Hoya is not toxic to humans, but its sap can irritate sensitive skin, so it's recommended to wear gloves when pruning or handling the plant.

For pets, it can be mildly toxic if ingested in large quantities, potentially causing digestive issues, vomiting, or diarrhea. Place the plant out of reach of pets.