The short answer
Windowsill herbs, a grow bag of tomatoes on a balcony, salad in a window box and sprouting seeds in a jar on the kitchen counter. All of them work in a flat.
- Herbs on a windowsill, which is the highest value per square centimetre available.
- Salad leaves in a window box, cut-and-come-again, resown every few weeks.
- Tomatoes or chillies in a pot on any sunny balcony or doorstep.
- Sprouting seeds or microgreens in a jar, which need no light at all for the first stage and are ready in days.
- Spring onions from the root ends of shop-bought ones, in water on the windowsill.
What will ruin it
Containers dry out far faster than open ground, particularly on a hot balcony. A pot that is missed for two days in July is usually finished, so scale what you grow to how reliably you can water it.
Why it works
Most edible plants care about light, water and root volume rather than about being in the ground. Give them enough of each in a container and they perform the same.
Tipking is general household information, not professional advice. Test anything on a hidden patch first. Full disclaimer.