Rebecca Trewin
Start by Reading Your Balcony
Before you buy a single pot, spend a week getting to know your balcony. This sounds like an indulgence, but it will save you money and heartache. Balconies are strange microclimates: they can be sunnier, windier, wetter or drier than the garden below, and often all four in the same day.
Check which way it faces. A south-facing balcony will bake in summer and may need watering twice daily, while a north-facing one will suit salad leaves, mint and ferns rather than tomatoes. Watch how the sun moves across the space: a balcony that seems gloomy in the morning may be in full sun by two o'clock.
Then think about wind. Anything above the first floor catches more of it than you would expect, and a gusty corner will shred tender plants and dry out compost fast. Also check the weight your balcony can take. Most modern balconies are fine with a good spread of pots, but a row of heavy glazed planters along one edge is asking for trouble. You will also need to know whether you are allowed to fix anything to the walls or railings — many leases and tenancy agreements have rules about this.
Pots, Tiering and Making the Most of the Space
Floor space is precious, so think upwards. Tiered planters, stacked pots and simple shelves that hook over the railing all multiply your growing room without eating into the area you need for a chair.
- Use a mix of sizes. One large pot (around 35–45cm across) holds moisture far better than several small ones and gives you a proper centrepiece.
- Tier with purpose. Put the tallest plants at the back or in the middle of a stack, medium ones in front, and let trailing plants spill over the edge.
- Choose lighter materials. Plastic, fibreglass and fabric grow bags weigh a fraction of terracotta or concrete, which matters if you are on an upper floor or need to move pots to clean underneath.
- Never forget drainage. Every container needs holes in the bottom and a few centimetres of crocks or gravel. Standing water kills more balcony plants than drought.
- Stabilise against wind. Heavy pots at the corners, lighter ones in the middle. If you use railing troughs, make sure they are properly secured.
The Compost Question
Lightweight compost is your friend, both for your back and for the balcony structure. Look for peat-free multipurpose compost and bulk it out with around a quarter to a third of perlite or vermiculite by volume. This keeps the mix airy, improves drainage and cuts weight considerably.
For hungry crops like tomatoes and courgettes, mix in a handful of slow-release fertiliser at planting time, then switch to a liquid feed once flowers appear. Salad leaves and herbs need far less — too much feed makes herbs leggy and tasteless.
Because balcony compost dries out quickly, it is worth adding a thin mulch of gravel or bark to the surface of larger pots. It looks tidy and slows evaporation. If you are growing something that hates drying out, such as fuchsias or busy Lizzies, consider a self-watering container with a built-in reservoir. They are genuinely useful if you work long days.
Compact Varieties Worth Growing
The secret to a good balcony garden is choosing plants bred to stay small. Ordinary garden varieties will simply outgrow the space and look straggly by July.
For edible growing, look for bush or patio types of tomato such as Tumbling Tom, which trails beautifully from a hanging basket, or Totem for a compact upright. Dwarf French beans, cut-and-come-again salad leaves, radishes, spring onions and strawberries all perform well in containers. Herbs are the balcony gardener's greatest reward: rosemary, thyme, chives and mint (always in its own pot, or it will take over) give you fresh pickings from a single windowsill-sized trough.
For flowers, choose trailing petunias, calibrachoa, trailing lobelia and nasturtiums, which are edible as well as pretty. Mix them with upright favourites like dwarf cosmos, salvia or geraniums for height. Nasturtiums and marigolds also help draw in pollinators and distract pests.
Watering, Feeding and Day-to-Day Care
Balcony containers need more attention than a garden border, but the routine is simple once established.
- Water in the morning where possible, so foliage dries before evening and you avoid mildew.
- Check daily in summer by pushing a finger into the compost. If it is dry 2cm down, water until it runs out of the drainage holes.
- Feed weekly from mid-spring to late summer with a balanced liquid feed; switch to a tomato feed for fruiting crops once flowers set.
- Deadhead regularly to keep flowers coming and stop plants putting energy into seed.
- Watch for pests — greenfly, whitefly and red spider mite love the sheltered warmth of a balcony. A strong jet of water and a squirt of soapy spray deals with most early infestations.
Getting Through the Seasons
A balcony garden does not have to end in September. In autumn, swap summer bedding for cyclamen, pansies and ornamental cabbages, and plant bulbs in your largest pots for a spring display. Move tender plants like citrus and olive trees against a sheltered wall, and wrap pots in bubble wrap or hessian to protect roots from hard frosts. Terracotta can crack in freezing weather, so if you have invested in it, raise pots onto feet so water drains freely.
Come February, a quick tidy, a top-up of fresh compost and a scatter of slow-release feed will have everything ready to start again. Small space, small effort — but a balcony that gives you something to pick, sniff and sit beside all year round.
