Begonia ‘Black Fang’

A cultivated member of the rhizomatous group

Begonia ‘Black Fang’ is a horticultural selection belonging to the rhizomatous Begonias.

Rhizomatous Begonias occur naturally in several tropical regions. Many grow close to the ground in humid, sheltered forest sites, while climate and root substrate depend on the species.

How to keep Begonia ‘Black Fang’ healthy

Light

Give Begonia ‘Black Fang’ a position close to an east or north-east window, or within about 1 m of a south or west window behind a light curtain. Acclimate it gradually, since sudden intense exposure means the upper leaf surface bleaches or scars and the rhizome dries unevenly. In a shaded shelf position, petioles stretch, the mound opens and colour or surface texture becomes less clear. Use the newest mature leaf as the light check. Expect the dark leaf colour and sharply divided outline on healthy growth. Dim conditions reduce clarity and strength, but direct sun does not create more colour.

Watering

Begonia ‘Black Fang’ is ready for water after the upper 2–3 cm has dried while the shallow root zone below remains faintly moist. Rewet the entire root ball in one pass, allow full drainage and keep the drainage hole clear. Small sips leave dry pockets behind. Do not bury the rhizome in moist mix. Its feeder roots need moisture, while the rhizome itself needs an exposed, airy surface. Allow brief drying near the surface and water before the entire broad pot becomes dry. Test beneath the active end of the rhizome on ‘Black Fang’. An unused edge of a broad pot may dry at a different rate. Active growth, warm airflow and terracotta dry the mix faster than cool light, dense substrate or plastic.

Substrate and roots

The root structure of Begonia ‘Black Fang’ is a sideways-growing rhizome and a modest mat of delicate feeder roots. If using ready-made houseplant mix, adapt it to give the same structure as a light foliage mix that wets evenly yet drains freely around the shallow feeder roots. The mix must stay springy: dense peat traps water, but an overly coarse orchid mix leaves dry gaps around feeder roots. Follow the horizontal spread with a wide drainage pot. A deep pot simply holds more wet mix below the active roots. Keep the rhizome of ‘Black Fang’ uncovered and give its growing end open surface space.

Temperature

Aim for stable temperatures around 18–26 °C for Begonia ‘Black Fang’, using 15 °C as the lower limit. Keep both foliage and pot away from night-time glass chill and air-conditioning outlets. A heater under the sill creates uneven drying and can desiccate the window-facing leaves.

Humidity and airflow

Keep the humidity around Begonia ‘Black Fang’ steady. Moderate, stable humidity supports clean growth without keeping the plant persistently wet. Aim around 50–70% if new leaves catch or crisp as they open. Keep ‘Black Fang’ away from heater air while a soft new leaf is opening. Fresh air matters most after watering, cleaning or while a new leaf is opening.

Fertilising

Apply a complete foliage fertiliser at about quarter strength every five to six weeks to Begonia ‘Black Fang’ only while the plant is growing actively. Reduce the dose when light falls, the pot stays wet longer or fresh potting mix already contains fertiliser. Begonia roots are sensitive to concentrated salts, so avoid strong doses and fertilise only after the root ball is moist. Keep the dose modest for ‘Black Fang’. Colour and texture depend more on healthy growth and suitable light than extra feed.

Repotting

Give Begonia ‘Black Fang’ a new pot when the rhizome reaches the rim, roots fill the shallow pot, water moves unevenly or the substrate has compacted. Choose a pot only 2–3 cm wider. A fine Begonia root system performs best without a large volume of unused substrate. Lift the shallow root mass intact. Separate only a rhizome section that already has feeder roots and an active growing point. Continue feeding only while temperature, light and active growth support normal nutrient use. Set ‘Black Fang’ so the growing rhizome has room to advance across the fresh mix.

Support, pruning, handling and leaf care

Do not stake the petioles of Begonia ‘Black Fang’. Guide its surface rhizome across the mix so new leaves have room to form, and divide only a rooted section with a live bud. Keep the light direction steady while a leaf unfolds, then make any small rotation once it is firm. The narrow points on Begonia ‘Black Fang’ catch easily on sleeves and neighbouring plants. Lift dust with a soft brush while supporting the divided blade from below. Snip damaged or spent growth with a clean tool and keep cuts clear of wet substrate.

When Begonia ‘Black Fang’ needs attention

Dark leaves look almost black

Very deep pigment is normal across a dry, firm leaf with Black Fang’s usual markings. Rotate a doubtful leaf under strong indirect light. A translucent, papery or soft area spreading through the surrounding dark tissue is damage.

Jagged margins curl and turn brittle

The angular outline is part of Black Fang, but its narrow points can dry after an unevenly dry root ball, salt build-up or moving hot air. Check the pot and placement first. A fresh tear cuts across the natural teeth; a dry established tooth is not chewing damage.

A dry split on a dark leaf

The stiff, sharply outlined blade can catch on a shelf or neighbouring plant. A stationary dry split is mechanical, so give new leaves room and keep the healthy leaf. Remove it if the injured line turns wet or begins to soften toward the leaf stalk.

Compact centre suddenly collapses

Dense black foliage can hide a failing growth point. Several petioles dropping together, an odour or soft tissue require immediate action. Cut back to firm, healthy tissue immediately. Use an unaffected leaf or outer stem piece for propagation.

Keeping ‘Black Fang’ away from curious pets

‘Black Fang’, including its characteristic leaves, contains soluble calcium oxalates and is toxic to cats and dogs. A pet that chews the leaves or a stem may drool or vomit; buried roots create the greatest exposure during repotting. Keep the pot beyond a pet’s reach. Collect removed leaves and block access to exposed roots or crown pieces during repotting. Recheck access after moving furniture or placing the pot on a lower surface. If drooling, vomiting or swallowing follows contact with the leaves or a stem, contact a veterinarian. Bag discarded roots, spent substrate and cuttings after repotting, then wash hands.

What ‘Black Fang’ tells us

‘Black Fang’ is a dramatic horticultural name built from two ordinary English words. Black points to very dark colouring, while fang means a long, pointed tooth and suits the sharply textured impression of the foliage.

Charles Plumier named Begonia for Michel Bégon, a French official who supported botanical work.