Container Gardening for Small Spaces and Balconies

Why pots punch above their weight

A balcony, a doorstep, a windowsill that catches the afternoon sun — none of them look like much until you put a pot on them. Container growing gives you total control over the one thing British gardeners spend half their lives fighting: the soil. Fill a pot with good compost and you have perfect drainage, no clubroot, no buried weed seeds and no digging. You can move your entire garden into the shade during a heatwave or shuffle it along the wall as the sun shifts. Pests and diseases are easier to spot and easier to deal with when the plant is at waist height. The trade-off is simple: pots dry out faster, nutrients wash away with every watering, and roots have nowhere to run. Get those three things right and almost anything is possible.

Choosing the right container

Size matters far more than style. A plant in a generous pot survives a missed watering; the same plant in a tiny one might not survive an afternoon. As a rough guide, herbs and salad leaves are happy in 15–20cm pots, bush tomatoes and peppers want at least 30cm, courgettes and dwarf fruit trees need 45cm or more. When in doubt, go one size up.

Drainage holes are non-negotiable. Without them, compost turns into a soggy, airless block and roots rot. Stand pots on feet or bricks so water can escape freely, and tip out any saucer that stays full for more than a day.

• Terracotta looks lovely and breathes well, but dries out quickly and can crack in a hard frost.
• Glazed ceramic holds moisture better and shrugs off winter, though it is heavy once planted.
• Plastic and fibreglass are light, cheap and easy to move — ideal for balconies with weight limits.
• Fabric grow bags air-prune roots beautifully and suit tomatoes, peppers and potatoes.
• Self-watering planters with a built-in reservoir are a gift for anyone out at work all day.

Whatever you choose, check the weight of the pot, the compost and the plant together before you fill a balcony with it. A large ceramic pot can easily weigh 40kg once watered.

Compost and feeding

Use fresh, peat-free multi-purpose compost each year. Old compost has collapsed, lost its structure and may be harbouring vine weevil grubs, so spread it on the borders rather than reusing it in pots. For long-term plants such as shrubs or small trees, mix in some loam-based John Innes No. 2 for weight and staying power. Add a handful of horticultural grit or perlite to improve drainage, but skip the old tradition of a layer of crocks in the base — it actually raises the water table inside the pot.

Feeding is where container gardeners win or lose. Compost holds only a few weeks of nutrition, so start liquid feeding once plants are growing strongly. A general-purpose feed suits foliage and flowers; switch to a high-potash tomato feed once flowering begins to encourage fruit. Slow-release granules mixed in at planting buy you time, but they are a cushion, not a substitute. Little and often beats a strong dose now and then.

Watering without the guesswork

Push a finger two knuckles deep into the compost. If it feels dry, water until it runs out of the drainage holes. Watering little and often wets only the surface, encouraging shallow, fragile roots; a thorough soak encourages roots to travel down. In summer, that may mean watering once a day, and twice for thirsty crops like courgettes and tomatoes in full sun.

Water in the morning where you can, so foliage dries before evening and slug activity begins. A 2cm mulch of gravel, bark or wool compost on the surface slows evaporation dramatically. Group pots together so they shade one another, and move them into a cooler corner during a heatwave. If you are away often, self-watering reservoirs or a simple drip kit on a timer will save more plants than any other purchase.

What to grow in a small space

Almost everything, provided you choose compact varieties. Look for the words dwarf, bush, patio or trailing on the seed packet.

• Herbs: basil, thyme, rosemary, chives and parsley all thrive in pots. Keep mint in its own container — it will otherwise take over.
• Salad and quick crops: cut-and-come-again leaves, radishes, spring onions and rocket give you a harvest within weeks.
• Vegetables: bush tomatoes such as Tumbling Tom, chillies, dwarf French beans, peas and a single courgette plant will crop generously from a sunny spot.
• Fruit: strawberries in a tall planter, plus dwarf blueberries in ericaceous compost.
• Flowers: pelargoniums, petunias, cosmos, nasturtiums and calendula bring colour — and nasturtium leaves and petals are edible.

Making a tiny space work hard

Think vertically. Wall-mounted troughs, tiered herb ladders and hanging baskets double your growing area, while a sturdy trellis lets climbing beans and sweet peas run upwards instead of outwards. Balconies are windier than gardens, so choose tough plants, weight pots at the base and consider a slim windbreak of bamboo screening. Slugs and vine weevil still find their way up, so check pots weekly and inspect compost surfaces for telltale notches and grubs. Rotate what you grow each year, refresh the compost, and your modest collection of pots will quietly out-produce many a vegetable bed.