Hoya krohniana ‘Black Leaves’

A dark-leaved Hoya krohniana selection

‘Black Leaves’ is a cultivated form whose foliage deepens towards dark olive or purple-green. Hoya krohniana is a small-leaved trailing epiphyte native to the Philippines.

Care for waxy-leaved epiphytes

• Placement: Choose a bright site with gently filtered direct sun. Stronger filtered light may deepen the dark leaf colour, but dry bleached patches show that exposure increased too quickly.
• Watering and root mix: Check the mix below the surface before watering, because a firm leaf can hide a dry or waterlogged root ball. Its fine roots need a short dry interval without becoming crisp, and the centre of the pot must not stay saturated.
• Airflow: Avoid leaving the mix around the roots against cold glass or in motionless humid air. Use moderate humidity with enough airflow for the foliage to dry.
• Feeding: Reserve dilute balanced nutrition for periods of visible root and stem growth. Allow more time between applications when new growth pauses.
• Fine trailing growth: Keep the small leaves clear of dense wet moss and let the stems branch freely over the pot edge or a light support.

Common issues with Hoya krohniana ‘Black Leaves’

• Leaves lose firmness while the mix remains damp: The container is holding water around compromised roots for too long. Slide the root system free and trim away all dark decaying roots. Set the cleaned roots into a smaller pot, keep the base of the vine clear and wait until the mix has dried sufficiently before rewatering. Remove a firm green node for propagation while the stem is still unaffected.
• A new dark leaf develops a bleached centre: A hot window raised leaf temperature and produced local dehydration. Filter the light with a sheer curtain or increase the distance from the glass. Keep the dark leaf unless the damaged area becomes wet or enlarges; then remove it at the petiole.
• New small dark-stemmed leaves emerge twisted with black specks or silvery scars: The unopened blade is harbouring feeding thrips. Quarantine it, rinse the upper and lower leaf surfaces and cut away ruined tip growth. Patch-test insecticidal soap, treat according to its label, and use a blue trap to catch adult thrips.
• Dark foliage becomes olive green: Light is lower than before or the leaf has not finished hardening. Keep the affected leaf unless it softens, becomes wet or develops spreading damage. Softness, dryness or spreading edges indicate a real tissue problem.

Hoya krohniana ‘Black Leaves’ is non-toxic to people and pets

• This plant is non-toxic to people, cats and dogs.
• Chewing a large amount can still cause an upset stomach.
• If a large amount is eaten and symptoms continue, contact a veterinarian or medical professional.

What does Hoya krohniana mean, and who first published it?

Hoya honours the English gardener Thomas Hoy. The epithet krohniana honours the Krohn family connected with the original cultivated material.

Robert Brown established the genus Hoya in 1810 in Prodromus Florae Novae Hollandiae, page 459.

Robert Dale Kloppenburg and Monina V. Siar first described Hoya krohniana in 2009 in Fraterna, volume 22, issue 4, page 9.