Planning a Low-Cost Balcony Garden in Britain

Start by Reading Your Balcony

Before you spend a penny, stand on your balcony and note three things: which way it faces, how much wind it takes, and how much weight the structure can carry. A south-facing balcony can be a sun trap that dries compost out by teatime, while a north-facing one may get only a couple of hours of weak light — which rules out lavender and tomatoes but suits mint, chives and ferns beautifully. Wind is the real enemy. Anything above the first floor funnels gusts that snap stems and strip moisture from leaves, so watch how the wind moves across the space on a blustery day and find the corner the building itself shelters. That corner is where your tender plants should live.

It is also worth checking your lease or tenancy agreement before you drill, hook or clamp anything to the wall. Many flats prohibit fixing to the facade, so plan around freestanding shelving, tiered planters and pots you can move.

Pots, Compost and the Weight Question

Size matters more than style. A 30cm pot is the sensible minimum for a single herb, and you want 40–45cm for a tomato or a small shrub. Bigger pots hold more compost, which means less watering and steadier roots — and they are far harder to blow over. As a rough guide, a 40cm terracotta pot filled with damp compost can weigh 20kg or more, so distribute the load near the wall rather than the outer edge, and favour several medium pots over one enormous one.

• Terracotta looks lovely but wicks moisture away; line it with plastic or choose it only for drought-lovers such as thyme and rosemary.
• Glazed or plastic pots hold water far better and are lighter to move.
• Always check drainage and raise pots on feet or broken tiles so they do not sit in a puddle.
• Use saucers to avoid drips on the neighbour below, and group pots together — clustering creates its own humid microclimate.

Fill with a multipurpose compost, or mix it half-and-half with a soil-based compost for extra weight and structure. Skip water-retaining granules for Mediterranean herbs, which hate sitting wet.

Herbs That Earn Their Keep

Herbs give you the best return on a small space, because you actually use them. The tough, woody sorts are made for exposed balconies: rosemary, thyme, sage, oregano and winter savory all cope with wind, salt and neglect, and they prefer lean, gritty compost.

• Rosemary — try a prostrate form for trailing over a wall or the front of a pot.
• Thyme and oregano — low-growing, happy in a shallow bowl, and evergreen in most UK winters.
• Chives and parsley — reliable in partial shade and cut-and-come-again through summer.
• Mint — always in its own pot, or it will colonise everything else within a season.
• Bay — a clipped standard makes a handsome windbreak and lives for years.

Basil is the exception: it needs real warmth, so give it the sunniest, most sheltered spot from June onwards.

Flowers That Shrug Off the Wind

Forget tall, floppy cottage-garden favourites. Delphiniums, lupins and cosmos will be flattened by July. Choose plants with flexible stems, fine foliage that lets the wind through, and a taste for dry roots.

• Lavender — compact varieties such as 'Hidcote' stay tidy and smell wonderful; give it lime and sharp drainage.
• Catmint and salvias — long-flowering, bee-friendly and happy in a pot.
• Erigeron and sedum — daisy-like flowers and late colour with almost no fuss.
• Verbena bonariensis and Stipa tenuissima — airy, translucent and surprisingly wind-tolerant.
• Nasturtiums — cheap from seed, thrive on poor soil, and the flowers are edible.

Add trailing ivy, lobelia or calibrachoa around the rim to soften the edges of a pot and hide bare compost.

Watering, Feeding and Keeping Costs Down

Balcony pots dry out fast. In high summer, check every morning and water until it runs from the base; on a hot, breezy day you may need a second pass in the evening. Water early rather than at midday, and mulch the surface with gravel or bark to slow evaporation. If you are out at work, a simple wick made from capillary matting and a reservoir bucket will keep things alive, and self-watering pots are worth the investment for thirsty crops.

Feeding is where beginners overshoot. Tomatoes and peppers want a high-potash feed weekly once flowering starts, but rosemary, thyme and lavender resent rich compost — feed them once in spring, if at all.

Small-Space Tricks and a Year of Colour

Use height rather than floor area. A tiered planter, a shelf unit against the wall or a short ladder gives you three or four growing levels in the footprint of one pot. Secure anything on a railing with brackets or a bungee cord, and never balance a pot on a narrow edge.

Plan for twelve months, not just June. Dwarf narcissi and crocus in spring, herbs and salad in early summer, annuals at their peak in July and August, sedums and heathers in autumn, then skimmia, ivy and winter pansies to see you through to February. Buy small plants in spring, divide perennials, and take cuttings of pelargoniums and fuchsias in late summer — a balcony garden that costs very little is usually one that keeps renewing itself.