Growing vegetables and herbs in containers and on balconies

In garden soil, roots can grow wide and deep and draw water and nutrients from a large area. In a pot, this supply is limited. The soil dries out faster, warms up or cools down faster, and the nutrients are used up after a few weeks. The larger the container, the more buffer the plant has and the more stable the conditions.

Plants take up water through their roots and need air there at the same time. If water stands in the pot permanently – this is called waterlogging – the roots suffocate and begin to rot. That is why every container needs a drainage hole. A saucer catches the water that drains out, but should not stand full all the time.

Garden soil is not well suited to pots because it easily compacts and turns hard there. Bought potting compost is looser, holds water better and contains nutrients to begin with. After a few weeks you need to feed again, ideally following the directions on the pack.

The site decides what grows. Watch for a day how many hours of sun your balcony gets. Fruiting vegetables such as tomatoes and chillies need a sunny, warm spot. Lettuce, chives, parsley and many other herbs also cope with partial shade. A shady north-facing balcony is better suited to leafy greens than to fruiting vegetables.

Choose containers to match: large tubs for tomatoes, balcony boxes for herbs and lettuce, shallow trays for radishes or cress. Dark pots in full sun heat up a lot, and clay pots dry out faster than plastic. Wind dries out the soil even more – on windy spots a windbreak helps.

Water when the top layer of soil is dry – check with your finger. On hot days that is often daily, ideally in the morning or evening. Water thoroughly until water runs out at the bottom instead of giving just a few drops. Harvest herbs and lettuce regularly; this encourages the plant to put out new growth. Put tender plants outside only after the last frosts.

Wet soil is heavy. A large tub of damp soil with a fully grown tomato plant can weigh as much as a child. Pay attention to what your balcony may carry and place heavy containers along the house wall rather than in the middle or on the railing. When in doubt, ask the landlord or building management.

Boxes and pots on railings and windowsills must be securely fixed or hang on the inside. Gusts of wind can knock pots over and blow them off the balcony – falling objects can seriously injure people below. Before storms, it is better to clear away loose containers.

Wash your hands after working with soil and wash produce before eating it. Make sure saucers do not drip onto the neighbours' balcony. Rules on balcony planting, weight and fixing may be set in tenancy agreements or house rules – check local rules.

A balcony garden is ideal for anyone living in a flat without a garden who wants to start gardening. It costs little, needs little space and brings fresh herbs and lettuce into the kitchen. Above all, you learn along the way: when to sow, how much water plants need, what pests look like. This knowledge also helps later in a bigger garden.

Realistically, it is not a source of stocks. Yields are small, and in summer watering costs time and water every day. Anyone preparing for a crisis still needs a food and water stock – the balcony at most adds something fresh to it.

Growing in pots is especially nice with children. Cress on the windowsill sprouts after a few days, and children see a result straight away. Anyone who waters and harvests their own plant understands much better where food comes from.

Gardening handbooks such as the RHS Encyclopedia of Gardening cover container gardening in detail – from choosing containers and compost to watering and feeding. Seed packets usually say when and how deep to sow; this information is a good starting point because it matches the particular variety.

Rainwater from a barrel is good for watering if you have access to one. A watering can filled in the evening is at the outside temperature by morning – many plants prefer that to ice-cold water.

You can put old potting compost on the compost heap or refresh it with fresh compost and soil. Sowing instead of buying young plants saves money, and later you may be able to save your own seed – that is a topic of its own.