Soil & potting mix
Best soil for Bok Choy 'Black Summer' (Brassica rapa var. chinensis 'Black Summer')
Also called Black Summer bok choy, dark bok choy.
More about bok choy 'black summer'
About Bok Choy 'Black Summer'
Brassica rapa var. chinensis 'Black Summer' · also called Black Summer bok choy, dark bok choy · edible
'Black Summer' is a fast, uniform bok choy with very dark green leaves and crisp pale stalks, bred for slow bolting and heat tolerance so it crops reliably through warmer weather. A cool-season Asian green, it matures in roughly six to eight weeks and is ideal for successional sowing in spring, summer, and autumn for stir-fries and steaming.
Preferred mix: Fertile, moisture-retentive loam
Watch for — Bolting: Heat, long days, and root stress make plants run to flower prematurely. Use this heat-tolerant variety, sow in cooler windows, and keep moisture even.
Why bok choy 'black summer' needs this mix
Bok Choy 'Black Summer' hates drying out, so it wants a mix that stays evenly moist — but it still needs perlite so "moist" never tips into "waterlogged".
- Bok Choy 'Black Summer' comes from damp, shaded forest floors and has fine roots that scorch and brown the moment the rootball dries — the mix has to hold a steady reserve.
- Coir and compost give that reserve, while perlite keeps enough air that the constantly-moist mix does not turn anaerobic.
- Even moisture also keeps its thin leaves from crisping at the edges, which is this plant’s most visible stress signal.
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 bok choy 'black summer' struggles, and the damage often shows up weeks later as a watering problem. For this species specifically:
- A free-draining, gritty mix dries too fast for bok choy 'black summer' — you get crispy brown edges and frond or leaf drop within days of one missed watering.
- A pure, airless peat mix swings the other way: it holds water but suffocates the fine roots and rots the crown.
- Letting the mix dry to the point it shrinks from the pot is very hard to re-wet evenly and stresses the plant badly.
Using a sharp, fast-draining "houseplant" or cactus-leaning mix that lets bok choy 'black summer' dry out. It needs a moisture-retentive but still airy blend.
pH — does it matter for bok choy 'black summer'?
Bok Choy 'Black Summer' prefers a slightly acidic mix (around pH 5.5-6.5); a peat-free compost-and-coir blend sits there naturally, so routine pH testing is unnecessary.
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 good peat-free houseplant compost works for bok choy 'black summer' straight from the bag if you mix in some perlite for air. The DIY ratio above gives a more reliable moisture-to-air balance.
Drainage and the pot
Use a pot with a drainage hole but a less-porous material (plastic or glazed) so it does not dry too fast. Bottom-watering keeps the mix evenly moist without sogging the crown.
Peat-free mixes slump and compact as they hold moisture, so refresh bok choy 'black summer''s mix every 12-18 months to keep air in the rootball even if the pot size is unchanged. When the time comes, our repotting guide for bok choy 'black summer' covers the timing and technique step by step.
Bok Choy 'Black Summer' soil — frequently asked questions
What is the best soil mix for bok choy 'black summer'?
3 parts peat-free houseplant compost : 1 part coco coir : 1 part perlite. Bok Choy 'Black Summer' comes from damp, shaded forest floors and has fine roots that scorch and brown the moment the rootball dries — the mix has to hold a steady reserve.
Can I use normal potting soil for bok choy 'black summer'?
A free-draining, gritty mix dries too fast for bok choy 'black summer' — you get crispy brown edges and frond or leaf drop within days of one missed watering. A good peat-free houseplant compost works for bok choy 'black summer' straight from the bag if you mix in some perlite for air. The DIY ratio above gives a more reliable moisture-to-air balance.
Does bok choy 'black summer' need a special pH?
Bok Choy 'Black Summer' prefers a slightly acidic mix (around pH 5.5-6.5); a peat-free compost-and-coir blend sits there naturally, so routine pH testing is unnecessary.
Should I buy a bagged mix or make my own for bok choy 'black summer'?
A good peat-free houseplant compost works for bok choy 'black summer' straight from the bag if you mix in some perlite for air. The DIY ratio above gives a more reliable moisture-to-air balance.
How often should I refresh the soil for bok choy 'black summer'?
Peat-free mixes slump and compact as they hold moisture, so refresh bok choy 'black summer''s mix every 12-18 months to keep air in the rootball even if the pot size is unchanged. Use a pot with a drainage hole but a less-porous material (plastic or glazed) so it does not dry too fast. Bottom-watering keeps the mix evenly moist without sogging the crown.
Keep reading
- Bok Choy 'Black Summer' care — the full brief (light, water, humidity, problems, pet safety)
- How often to water bok choy 'black summer' — the schedule the mix feeds into
- Repotting bok choy 'black summer' — when and how to refresh the mix
- Soil pH guide — test it and adjust it safely
- Underwatered plant — signs and how to rehydrate it
- Why is my plant wilting? Wet vs dry diagnosis
- Should I water my plant? The simple check first
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