Begonia × ricinifolia ‘Immense’

A historic hybrid between two tropical American species

Begonia × ricinifolia is an artificial hybrid between B. barkeri and B. heracleifolia, first published in 1847. ‘Immense’ is an old, exceptionally large-leaved horticultural form of this hybrid.

Both parent species are native to tropical America. The hybrid arose in cultivation from those two tropical American parents, and ‘Immense’ was retained for its exceptional leaf size.

Watering and root care for rhizomatous plants

Watering

water Begonia × ricinifolia ‘Immense’ when the upper layer of the substrate has dried and the broad pot feels lighter, while the lower root zone remains lightly moist. The substantial rhizome holds reserve, yet a long dry spell sacrifices fine roots and causes the large leaves to collapse.

Light

A practical home position for Begonia × ricinifolia ‘Immense’ is near a large east window or a short distance from bright south or west glass with hot direct sun filtered. Strong healthy leaves display the immense palmate leaf size and sturdy crown naturally.

Substrate and roots

Plan the potting mix around a thick surface rhizome with a wide, shallow network of feeder roots. Fine heavy compost forms an airless core beneath the large rhizome, especially in an oversized pot.

Humidity and airflow

Begonia × ricinifolia ‘Immense’ grows best when humidity stays steady. Give each expanding leaf on the plant open space and keep it outside the direct stream of a heater.

Root care and watering

Give Begonia × ricinifolia ‘Immense’ fresh mix once the thick rhizome reaches the container edge, the crown becomes unstable, water channels through or the substrate has collapsed. Preserve the central rhizome and its anchoring roots.

Root care and leaf care

Stand Begonia × ricinifolia ‘Immense’ in a heavy broad pot and give every large leaf room to open. Guide the thick surface rhizome and prune a damaged leaf cleanly at its base.

If Begonia × ricinifolia ‘Immense’ looks unwell

Massive palmate leaves droop or tear

Large mature blades can arch and split under their own weight or after contact. A dry, stable tear is mechanical damage. Stabilise the pot and give the large leaves enough clearance. If a whole leaf suddenly becomes limp, check the root ball. Remove a soft brown tear before decay spreads along the leaf.

Deep lobes brown at their many tips

The numerous points lose moisture before the broad crinkled centre after uneven watering, salt accumulation or a heater draught. Feel the mix and look for salt on the surface, then correct the watering or airflow problem. Keep the large rhizome evenly moist with good drainage. New growth will replace the dead tips.

Hairy stems carry white clusters

The cultivar’s red-brown hairs are evenly distributed along sturdy petioles. Mealybugs form separate cottony masses at joints; scale forms discrete removable bumps and may produce honeydew. Compare several petioles before treating. If cottony masses or removable bumps are present, isolate the plant and treat the pest throughout the large canopy.

A top-heavy, sprawling rhizome

Begonia ‘Immense’ naturally spreads and can lever a shallow root ball out of the pot. Move a healthy plant to a wider, stable container and anchor the rhizome at the surface. Cut away any bend that is dark and soft.

Several giant leaves collapse from one point

Trace the fallen stalks back through the huge canopy. If they all meet at one soft section, cut that part away until the exposed interior is consistently firm and clean. Root the healthy end at the surface and take a leaf cutting immediately when the last healthy growing point is involved.

Begonia × ricinifolia ‘Immense’ is toxic to people and pets

• Keep this plant away from children, cats and dogs.
• The roots and rhizomes contain the highest levels of soluble oxalates, and the sap can irritate skin.
• Chewing may cause mouth irritation, drooling, vomiting or stomach pain. Contact a veterinarian or medical professional if symptoms develop.

How did Begonia × ricinifolia get its name?

Begonia honours Michel Bégon. The epithet ricinifolia means castor-oil-plant-leaved and refers to the broad, deeply lobed foliage.

Carl Linnaeus established the genus Begonia in 1753 in Species Plantarum, page 1056.

Albert Gottfried Dietrich first described Begonia × ricinifolia in 1847 in Allgemeine Gartenzeitung, volume 15, page 282.