Soil & potting mix
Best soil for Begonia 'Looking Glass' (Begonia rex-cultorum 'Looking Glass')
Also called looking glass begonia, silver rex begonia.
More about begonia 'looking glass'
About Begonia 'Looking Glass'
Begonia rex-cultorum 'Looking Glass' · also called looking glass begonia, silver rex begonia · houseplant
Begonia 'Looking Glass' is a rex-cultorum hybrid grown for its dramatic foliage: large, asymmetric leaves washed in metallic silver with olive-green veins and deep red undersides. A rhizomatous houseplant, it demands bright indirect light and steady humidity but resents soggy roots. Flowers are insignificant; the shimmering leaves are the entire point of growing it.
Preferred mix: Light, airy, free-draining mix
Watch for — Crown and root rot: Overwatering or a buried rhizome causes soft, collapsing stems; keep the rhizome on the surface and let soil dry slightly between waterings.
Why begonia 'looking glass' needs this mix
Begonia 'Looking Glass' wants a light, fine, evenly moist mix — soft-rooted and crown-sensitive, it suits an airy 1:1:1 blend, not heavy compost.
- Begonia 'Looking Glass' has fine, shallow roots and a crown that rots if it sits wet, so the mix must be light, airy and only evenly moist.
- Equal parts compost, perlite and vermiculite give steady moisture and plenty of air at once — the balance this plant flowers on.
- A heavy, dense mix smothers the fine roots and is the usual reason it sulks and refuses to bloom.
For the full picture on what makes up a good mix, see our guide to the main types of soil and potting media — it explains why each ingredient above behaves the way it does.
What goes wrong with the wrong mix
The wrong soil is one of the most common reasons begonia 'looking glass' struggles, and the damage often shows up weeks later as a watering problem. For this species specifically:
- Heavy, water-holding compost rots begonia 'looking glass''s crown and fine roots — the plant goes limp and mushy at the centre.
- A coarse, gritty cactus-style mix dries too fast and the fine roots desiccate.
- Burying the crown when potting (rather than keeping it just at the surface) causes rot even in a good mix.
Using heavy compost and burying the crown. Begonia 'Looking Glass' wants a light 1:1:1 mix with the crown sitting right at the surface.
pH — does it matter for begonia 'looking glass'?
Begonia 'Looking Glass' is not fussy about pH — a slightly acidic to neutral mix (around pH 6.0-7.0), which a standard peat-free compost provides, is perfectly fine. No testing needed.
If you want to check or adjust it, the soil pH guide walks through testing and the safe ways to nudge a mix more acidic or more alkaline.
DIY mix vs a bagged one
A decent bagged houseplant compost works for begonia 'looking glass' as long as you mix in perlite for air. The simple DIY ratio above is cheap and more reliable than a budget bag alone.
Drainage and the pot
Use a small pot with a drainage hole and water from the bottom to keep the crown dry — wet leaves and a wet crown are this plant's main enemies.
Refresh begonia 'looking glass''s mix every 18-24 months; even good compost slumps and compacts, and fresh, airy mix is often the simplest fix for a tired plant. When the time comes, our repotting guide for begonia 'looking glass' covers the timing and technique step by step.
Begonia 'Looking Glass' soil — frequently asked questions
What is the best soil mix for begonia 'looking glass'?
1 part peat-free houseplant compost : 1 part perlite : 1 part vermiculite. Begonia 'Looking Glass' has fine, shallow roots and a crown that rots if it sits wet, so the mix must be light, airy and only evenly moist.
Can I use normal potting soil for begonia 'looking glass'?
Heavy, water-holding compost rots begonia 'looking glass''s crown and fine roots — the plant goes limp and mushy at the centre. A decent bagged houseplant compost works for begonia 'looking glass' as long as you mix in perlite for air. The simple DIY ratio above is cheap and more reliable than a budget bag alone.
Does begonia 'looking glass' need a special pH?
Begonia 'Looking Glass' is not fussy about pH — a slightly acidic to neutral mix (around pH 6.0-7.0), which a standard peat-free compost provides, is perfectly fine. No testing needed.
Should I buy a bagged mix or make my own for begonia 'looking glass'?
A decent bagged houseplant compost works for begonia 'looking glass' as long as you mix in perlite for air. The simple DIY ratio above is cheap and more reliable than a budget bag alone.
How often should I refresh the soil for begonia 'looking glass'?
Refresh begonia 'looking glass''s mix every 18-24 months; even good compost slumps and compacts, and fresh, airy mix is often the simplest fix for a tired plant. Use a small pot with a drainage hole and water from the bottom to keep the crown dry — wet leaves and a wet crown are this plant's main enemies.
Keep reading
- Begonia 'Looking Glass' care — the full brief (light, water, humidity, problems, pet safety)
- How often to water begonia 'looking glass' — the schedule the mix feeds into
- Repotting begonia 'looking glass' — when and how to refresh the mix
- Soil pH guide — test it and adjust it safely
- Should I water my plant? The simple check first
- Overwatered plant — signs and recovery
- Root rot — how the wrong soil starts it, and how to save the plant
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