Repotting guide
When & how to repot Begonia (Begonia × hortensis)
Also called wax begonia, bedding begonia, fibrous begonia.
About Begonia
Begonia × hortensis · also called wax begonia, bedding begonia · flowering
Bedding begonias are tender perennials grown as compact annuals with waxy leaves and small white, pink, or red flowers. Tolerate sun and part shade. Mildly toxic to pets through soluble calcium oxalates in tubers and stems.
Begonia is a tropical and subtropical forest-understory genus; tuberous types trace to montane South America and southern Africa. Garden begonias split into three habits: fibrous-rooted wax (Semperflorens), tuberous, and rhizomatous foliage types.
Demands sharply well-drained media at a slightly acidic pH around 5.5 to 6.5; standing moisture quickly triggers tuber and root rot.
Mature size: 20-30 cm tall
Watch for — Yellow lower leaves: Overwatering or root-bound.
Sources: extension.umn.edu, extension.umn.edu, rhs.org.uk
How to tell begonia needs repotting
Repotting on a calendar is less reliable than reading the plant. For begonia, watch for these signs:
- Roots circling the bottom of the module or pot, or poking out of the drainage holes.
- The seedling dries out within a day and growth has visibly stalled.
- Roots are white and matted in a tight spiral when you tip the plant out.
- It has outgrown its current container for the stage of the season — pot begonia on before it becomes hard root-bound.
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 begonia
Pot on seedlings as they grow; not a perennial repot. Begoniais grown for one season, so the question is really “how often to pot on” — keep moving it up before the roots circle. Compact bushy annual.
What size pot to step begonia up to
Pot begonia on gradually — a seedling jumped straight into a huge pot sits in cold, wet, airless soil and stalls. Step up one or two sizes at a time as the roots fill each container, finishing in a large final pot or the ground. The aim is roots that never circle and never check.
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 begonia
Pot begonia on through the active growing season, whenever roots fill the current container — there is no single date, just "before it becomes root-bound". Avoid potting on during a cold snap.
Step-by-step: repotting begonia
- Pot on before it is root-bound. Check begonia regularly; move it up as soon as roots reach the edge of the cell or pot, not after they have circled.
- Step up one or two sizes. Choose the next container up — not a giant one. Cold, wet, unused soil around a small root system stalls seedlings.
- Knock it out gently. Support the stem, tip the pot, and ease the rootball out without breaking it. A little teasing of circled roots at the base is fine.
- Pot into rich mix. Set it into fresh rich free-draining loam at the same depth (tomatoes are the exception — they can go deeper to root along the stem).
- Water in and grow on. Water well, keep it in good light, and resume feeding once it is established and growing again.
Aftercare
Water begonia in well and keep it in bright light; a freshly potted-on seedling can wilt for a day while roots settle, so do not overcompensate by drowning it. Do not fertilise for about 1 week — fresh mix already carries nutrients and feeding freshly disturbed roots scorches them.
The right soil mix for begonia
Begonia wants rich free-draining loam. pH 5.5-6.5. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.
Repotting begonia — frequently asked questions
How often should you repot begonia?
Pot on seedlings as they grow; not a perennial repot for begonia. Begonia is a seasonal crop, so you pot it on as a growing plant rather than repotting a perennial. Step seedlings up gradually into rich free-draining loam so the roots never circle the cell, ending in a large final container. A root-bound transplant stalls and never fully recovers.
What size pot does begonia need?
Pot begonia on gradually — a seedling jumped straight into a huge pot sits in cold, wet, airless soil and stalls. Step up one or two sizes at a time as the roots fill each container, finishing in a large final pot or the ground. The aim is roots that never circle and never check. Use our pot size calculator to size it from the plant's current pot and root spread.
When is the best time of year to repot begonia?
Pot begonia on through the active growing season, whenever roots fill the current container — there is no single date, just "before it becomes root-bound". Avoid potting on during a cold snap.
Can you put begonia straight into a much bigger pot?
No. Even a fast-growing begonia should only go up one pot size at a time. A vastly oversized pot holds a reservoir of wet soil the roots cannot reach, which stays cold and soggy and rots the roots — the opposite of what you wanted.
Should you fertilise begonia after repotting?
Not immediately. Wait about 1 week after repotting 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.
Related guides
- Begonia care — light, water, soil and common problems
- How often to water begonia — the watering brief
- How to repot a plant — the complete step-by-step method
- Root-bound plant — how to spot and fix it
- Pot size calculator — size the next pot correctly
- When & how to repot peace lily
- When & how to repot bird of paradise
- When & how to repot hoya
- All 200 repotting guides in the Growli library