Dendrobium kingianum aka Pink Rock Orchid

Dendrobium kingianum tolerates a wide temperature range, from brief exposure to near-freezing up to 40°C (105°F). Ideal summer temperatures are up to 25°C (77°F). Importantly, this orchid requires a cool winter rest period with temperatures dropping below 10°C (50°F) for 4-6 weeks to trigger flowering. Never allow it to freeze, but avoid keeping it too warm in winter or it may not bloom.

Dendrobium kingianum is nicknamed 'The Keiki Maker' due to its prolific production of baby plants (keikis) on older pseudobulbs. Wait until keikis develop 3-4 roots at least 5cm long before gently detaching and potting in small containers with orchid bark mix. Division is also effective—separate clumps into sections with at least 3 healthy pseudobulbs each, immediately after flowering. Allow cuts to dry for a few hours before repotting. Note that excessive keiki production may indicate stress or over-fertilization with nitrogen.

This is a compact orchid, with pseudobulbs typically reaching 20-35cm tall and plants spreading 10-50cm depending on age and growing conditions. RHS notes it takes 2-5 years to reach maturity. Given time, plants form impressive clumps—in their native Australian habitat, colonies can spread several metres across rock faces. In cultivation, a well-grown specimen in a 20cm pot with multiple flowering spikes is a spectacular sight.

Flowering occurs from late winter to mid-spring (February-April in the Northern Hemisphere, August-October in Australia). Each mature pseudobulb produces racemes up to 15cm long bearing 2-15 fragrant flowers that last 2-4 weeks. Flower size ranges from 1.5-4cm across. To encourage blooming, provide a cool, dry winter rest period for 4-6 weeks with temperatures around 8-10°C and minimal watering—this temperature drop is essential for flower initiation.

Yes, Dendrobium kingianum produces sweetly fragrant flowers. The scent is often described as honey-like or reminiscent of raspberries. Fragrance intensity varies between individual plants and color forms. The pleasant scent, combined with long-lasting blooms (up to 25 days), makes this species particularly rewarding for indoor growing where the fragrance can be appreciated.

Flower color varies considerably in this species, from pure white through shell pink to deep magenta-purple. The most prized form is var. silcockii (also called semi-alba), featuring crystalline white petals with a contrasting purple-marked lip—these are rare and highly sought after. Other recognized varieties include var. album (pure white), var. aldersonae, var. pallidum, and var. pulcherrimum. Selective breeding has produced cultivars with intensified purplish-red and speckled pink flowers.

In USDA zones 9-12 with frost-free winters, Dendrobium kingianum can be grown outdoors year-round. It thrives in subtropical and Mediterranean climates similar to its native eastern Australian range. Mount on trees or rocks, or grow in hanging baskets with excellent drainage. In cooler climates, it can be grown outdoors in summer but must be brought inside before temperatures drop below 5°C (41°F). Provide 50% shade cloth in hot climates to prevent leaf burn.

This orchid has distinct seasonal requirements. During the growing season (spring through autumn), water regularly when the medium approaches dryness and fertilize fortnightly with a balanced liquid fertilizer. From late autumn, gradually reduce watering and stop fertilizing. Winter is the crucial rest period: keep nearly dry, provide cool temperatures (ideally 8-10°C), and maximize light exposure. This 4-6 week cool, dry rest triggers flower bud formation. Resume normal care when flower spikes emerge in late winter.

Repot every 1-2 years, or when the potting medium breaks down and drainage deteriorates. The best time is immediately after flowering in spring. Use a pot just large enough to hold the roots with room for one season's growth—this orchid blooms better when somewhat pot-bound. Choose a bark and perlite mix or specialist orchid medium. Plants with poor root systems due to decayed mix often produce excessive keikis rather than flowers, signaling an urgent need to repot.

Dendrobium kingianum requires minimal pruning. Remove spent flower spikes after blooming by cutting at the base. Old, leafless pseudobulbs should generally be left in place as they store energy and can still produce flowers or keikis. Only remove pseudobulbs that have completely shriveled and dried. When dividing the plant, ensure each division retains at least 3 healthy pseudobulbs for best recovery and flowering.

Common pests include aphids and thrips (which attack flower spikes), mealybugs, scale insects, and red spider mites (which scar leaves). RHS confirms susceptibility to glasshouse red spider mite, aphids, and mealybugs. In Australia, the Dendrobium beetle is an additional concern. Treat infestations promptly with appropriate insecticides or horticultural oils. This orchid is generally disease-free when given proper air circulation. Root rot can occur in waterlogged conditions—ensure excellent drainage and allow the medium to dry between waterings.

Some yellowing of older leaves is natural as pseudobulbs age—this is not cause for concern. However, widespread yellowing may indicate overwatering and root rot (check roots and reduce watering), insufficient light (move to brighter location), or nutrient deficiency (resume balanced fertilizing during the growing season). If leaves also feel soft or mushy, root rot is likely—unpot, trim damaged roots, allow to dry, and repot in fresh medium. Yellow leaves with dry brown tips often indicate underwatering or low humidity.

Pink Rock Orchid’s native range is Southeast Asia.

Pink Rock Orchid should be watered regularly, allowing the soil to dry out between waterings.

Pink Rock Orchid loves a well-draining soil. Perlite and vermiculite help with drainage, while coco coir adds organic matter, so a good potting soil mix will have all three. You can improve store-bought soil by adding some perlite to it.

To ensure optimal growth, the Pink Rock Orchid prefers bright indirect light for 6-8 hours each day. Insufficient light can result in slow growth and leaf drop, so it's important to find a well-lit location for this plant. Place it near a window, within a distance of 1 meter (3 feet), to enhance its potential for thriving.

The Pink Rock Orchid does not need extra humidity. Plants primarily absorb water through their root system, making soil watering the best way to provide humidity to your plants.

The Pink Rock Orchid should be repotted when it has doubled in size or annually, whichever comes first. Providing fresh potting soil with all the essential nutrients each year ensures the plant's well-being, eliminating the need for fertilizer. Remember, plants derive their energy from the sun and not fertilizer.

Ploi lacks confirmed information on the toxicity of this plant. If you, a relative, or your pet accidentally consume plant material with unknown toxicity, it's best to consult a medical expert.