Soil and fertilizer basics for container vegetables

Dig soil straight out of the ground and dump it in a pot, and it compacts hard, almost like clay, and drains badly. It works fine outdoors because roots can spread out and worms keep it aerated — neither of which happens inside a container. Container vegetables need a mix built specifically for pots, and they need feeding on a schedule, because a pot only has so much nutrient stored in it, unlike open garden soil.

A simple mix that works for most vegetables

A reliable, easy-to-source ratio for Indian balconies:

• 50% garden soil or red soil — the base structure. Ask your local nursery for "red soil" or "garden mitti" if you don't have access to your own.
• 25% compost or well-rotted cow dung manure (gobar khad) — the main nutrient source. Cheap, widely available at nurseries, and works well for vegetables specifically.
• 25% coco peat, sand, or a mix of both — for drainage and aeration. Coco peat also holds moisture well, which matters on hot balconies where pots dry out fast.

Mix these together dry before filling the container. Always start with a layer of broken pot shards or pebbles right at the bottom, so the drainage hole doesn't clog with soil the first time you water.

Feeding once the mix runs out

A fresh mix carries enough nutrients for roughly 4–6 weeks of active growth. After that, vegetables, especially fruiting ones like tomatoes and chillies, need regular feeding to keep producing.

• Every 2–3 weeks: a liquid feed. Diluted compost tea or a liquid vermicompost extract, watered in at the base, is gentle enough to use often without burning roots.
• At flowering: a potassium boost. Wood ash (a small pinch, well diluted in water) or a bought potash-heavy fertilizer helps push energy into fruit rather than leaf growth. This makes a visible difference for tomatoes and chillies specifically.
• Leafy herbs need less feeding than fruiting vegetables. Coriander and mint do fine on compost alone and can be overfed into weak, floppy growth — save the stronger feeds for tomatoes, chillies, and other fruiting plants.
• Top-dress with fresh compost monthly. Scratch a thin layer of compost into the top few centimetres of soil every 4 weeks rather than digging it in deep, which disturbs roots.

Dealing with hard Indian tap water

Hard tap water, common in most Indian cities, gradually raises the mineral content and pH of container soil, which can lock out nutrients even when your feeding routine is spot on. Two habits help: let tap water stand uncovered for a day before using it, and flush each container thoroughly with extra water every few weeks so the mineral buildup washes through the drainage hole rather than sitting and accumulating. A white crust forming on the soil surface is the tell — scrape it off and top up with fresh mix rather than trying to water it away.

The plants working hardest need this the most. Tomatoes and chillies will stall on plain potting mix the moment fruiting starts, while coriander and mint are forgiving enough to be a good place to practice the basics first.