Repotting guide

When & how to repot Roxburgh's Begonia (Begonia roxburghii)

Also called Roxburgh's begonia, Red-dotted begonia, Himalayan begonia.

More about roxburgh's begonia

About Roxburgh's Begonia

Begonia roxburghii · also called Roxburgh's begonia, Red-dotted begonia · flowering

Begonia roxburghii is a caulescent (stemmed), erect species native to the Eastern Himalayas — northeast India, Nepal, Sikkim, Bangladesh, and Myanmar — growing at elevations between 300 and 1,850 m in forest margins and rocky slopes. Its stout stems reach 60-120 cm and are distinctively marked with red elongated dots or spots; it bears light pinkish-white flowers with yellow stamens. Being from a montane subtropical habitat, it tolerates cooler temperatures than most tropical begonias but still requires protection from frost; the key care point is providing bright indirect light combined with good drainage to replicate its rocky, well-drained native hillside habitat. Begonia roxburghii is toxic to cats, dogs, and horses.

Mature size: 60-120 cm (24-48 in) tall, 40-60 cm (16-24 in) wide in a container.

How to tell roxburgh's begonia needs repotting

Repotting on a calendar is less reliable than reading the plant. For roxburgh's begonia, watch for these signs:

Thick roots out of the drainage holes, or circling the surface and lifting the plant.
The pot dries out unusually fast and roxburgh's begonia wilts between waterings it used to shrug off.
The plant is visibly top-heavy and tips over easily.
Stalled growth and small new leaves over a full season — though with a big specimen, top-dressing is often the better first response before a full repot.

For the underlying biology of a pot-bound root system and why it stalls a plant, see our guide to spotting and fixing a root-bound plant.

How often to repot roxburgh's begonia

Every 2–3 years; top-dress in the in-between years. Roxburgh's Begonia's growth habit — an erect, caulescent herb with a stout, slightly woody stem up to 5-20 mm wide, reaching 60-120 cm in height; stems are distinctively marked with red elongated dots and the plant is dioecious (separate male and female plants). — sets the pace. Begonia roxburghii is a caulescent (stemmed), erect species native to the Eastern Himalayas — northeast India, Nepal, Sikkim, Bangladesh, and Myanmar — growing at elevations between 300 and 1,850 m in forest margins and rocky slopes. Its stout stems reach 60-120 cm and are distinctively marked with red elongated dots or spots; it bears light pinkish-white flowers with yellow stamens. Being from a montane subtropical habitat, it tolerates cooler temperatures than most tropical begonias but still requires protection from frost; the key care point is providing bright indirect light combined with good drainage to replicate its rocky, well-drained native hillside habitat. Begonia roxburghii is toxic to cats, dogs, and horses.

What size pot to step roxburgh's begonia up to

Move up exactly one pot size. A heavy roxburgh's begonia dropped into a vastly bigger pot sits in a reservoir of wet soil its roots cannot reach, which rots them and destabilises the plant. In the years between repots, lift off and replace the top 3–5 cm of soil (top-dressing) instead — it refreshes nutrients without the shock of a full repot.

Not sure of the exact diameter? Our pot size calculator takes the current pot and root spread and tells you the right next size — it deliberately recommends a single step up, never a big jump.

The best time of year to repot roxburgh's begonia

Early spring, just as new growth restarts, is the ideal window for roxburgh's begonia. The plant is moving into its strongest growth phase and re-roots into fresh soil quickly. Avoid repotting in winter dormancy or, for flowering plants, while it is in bud or bloom — recovery is slowest then and you risk dropping the flowers.

Step-by-step: repotting roxburgh's begonia

Consider top-dressing first. If roxburgh's begonia is not badly root-bound, scrape off and replace the top 3–5 cm of soil instead — far less shock for a big plant that hates moving.
Get help and one size up. For a full repot, choose a pot just one size larger. A heavy plant needs two people and a stable, free-draining pot.
Ease it out on its side. Lay the plant down, slide the pot off, and gently loosen the outer roots. Do not bare-root a mature specimen.
Repot at the same depth. Add fresh well-draining, organically rich mix beneath and around the rootball, keeping the original soil line. Firm it so the trunk is stable and upright.
Water and leave it put. Water thoroughly, then leave roxburgh's begonia in the same spot and light — moving and repotting at once is what makes it drop leaves.

Aftercare

Leave roxburgh's begonia in exactly the same spot and light it was in before — moving and repotting at the same time is what makes a big specimen drop leaves. Water it in well, then let the top of the soil dry before watering again so the larger volume of fresh soil does not stay sodden. Do not fertilise for about 4 weeks — fresh mix already carries nutrients and feeding freshly disturbed roots scorches them.

The right soil mix for roxburgh's begonia

Roxburgh's Begonia wants well-draining, organically rich mix. A peat-free potting compost blended with 25% perlite and a small amount of coarse grit provides the drainage this hillside-growing species requires. Terracotta pots are beneficial as they allow the root zone to breathe and dry more evenly. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.

Repotting roxburgh's begonia — frequently asked questions

How often should you repot roxburgh's begonia?

Every 2–3 years; top-dress in the in-between years for roxburgh's begonia. Fully repot roxburgh's begonia only every 2–3 years; in the in-between years just top-dress the top 3–5 cm of soil. Step up one pot size in spring with well-draining, organically rich mix. It is heavy and hates being moved, and a vastly oversized pot holds water against the roots and rots them.

What size pot does roxburgh's begonia need?

When is the best time of year to repot roxburgh's begonia?

Should you top-dress or fully repot roxburgh's begonia?

For a big, heavy roxburgh's begonia, top-dressing — replacing the top 3–5 cm of soil — is the gentler option most years, with a full repot only every 2–3 years. A mature specimen sulks and drops leaves when fully repotted, so do it as rarely as the roots allow.

Should you fertilise roxburgh's begonia after repotting?

Not immediately. Wait about 4 weeks after repotting roxburgh's begonia. Fresh mix already contains nutrients, and feeding freshly cut or disturbed roots burns them. Resume your normal feeding routine once you see new growth.