Soil & potting mix
Best soil for Begonia grandis subsp. evansiana (Begonia grandis subsp. evansiana)
Also called Evans's hardy begonia, hardy chinese begonia.
More about begonia grandis subsp. evansiana
About Begonia grandis subsp. evansiana
Begonia grandis subsp. evansiana · also called Evans's hardy begonia, hardy chinese begonia · flowering
Begonia grandis subsp. evansiana is the hardiest begonia, a tuberous perennial with angel-wing leaves backed in red and airy sprays of pink (or white) flowers from midsummer to autumn. Holding an RHS Award of Garden Merit, it thrives in partial shade and humus-rich, well-drained soil, dies back in winter, and returns from underground tubers and bulbils.
Preferred mix: Fertile, humus-rich, well-drained, neutral to acid soil
Watch for — Slow or late emergence: This species breaks dormancy late in spring; bare soil is normal until early summer, so avoid disturbing or assuming it has died.
Why begonia grandis subsp. evansiana needs this mix
Begonia grandis subsp. evansiana wants a light, fine, evenly moist mix — soft-rooted and crown-sensitive, it suits an airy 1:1:1 blend, not heavy compost.
- Begonia grandis subsp. evansiana 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 grandis subsp. evansiana struggles, and the damage often shows up weeks later as a watering problem. For this species specifically:
- Heavy, water-holding compost rots begonia grandis subsp. evansiana'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 grandis subsp. evansiana wants a light 1:1:1 mix with the crown sitting right at the surface.
pH — does it matter for begonia grandis subsp. evansiana?
Begonia grandis subsp. evansiana 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 grandis subsp. evansiana 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 grandis subsp. evansiana'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 grandis subsp. evansiana covers the timing and technique step by step.
Begonia grandis subsp. evansiana soil — frequently asked questions
What is the best soil mix for begonia grandis subsp. evansiana?
1 part peat-free houseplant compost : 1 part perlite : 1 part vermiculite. Begonia grandis subsp. evansiana 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 grandis subsp. evansiana?
Heavy, water-holding compost rots begonia grandis subsp. evansiana's crown and fine roots — the plant goes limp and mushy at the centre. A decent bagged houseplant compost works for begonia grandis subsp. evansiana 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 grandis subsp. evansiana need a special pH?
Begonia grandis subsp. evansiana 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 grandis subsp. evansiana?
A decent bagged houseplant compost works for begonia grandis subsp. evansiana 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 grandis subsp. evansiana?
Refresh begonia grandis subsp. evansiana'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 grandis subsp. evansiana care — the full brief (light, water, humidity, problems, pet safety)
- How often to water begonia grandis subsp. evansiana — the schedule the mix feeds into
- Repotting begonia grandis subsp. evansiana — 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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