A single lavender in a window box is not a token gesture. For a buff-tailed bumblebee working a street of flats and paved front gardens, a windowsill of herbs in flower can be the difference between an easy meal and a long, hungry flight. Bees don't need a meadow. They need flowers that are open, generous with nectar, and available for as much of the year as you can manage.

The good news is that the plants bees love most are often the ones that thrive in pots, prefer poor soil and resent fussing. The trick is choosing the right ones, planting them in something that drains well, and keeping the water up through summer.

Why small spaces matter

Honeybees, bumblebees and solitary bees forage within a few hundred metres of their nests. In towns and cities, that range is mostly rooftops, pavements, hanging baskets and whatever survives in front gardens. Every planted windowsill adds to that network, and a handful of balconies on one street can create a genuine corridor of food.

You don't need to plant everything at once. Start with one box, see what visits, and add to it next season. Bees are quick to find reliable flowers, and once they do, they return to them day after day.

Pick flowers bees can actually use

Not all pretty flowers are useful. Many bedding plants sold for summer colour have been bred for show and offer little or no nectar. Double flowers are the worst offenders: all those extra petals have replaced the stamens and made the centre impossible to reach. If a flower looks like a tight ball of petals, a bee will usually ignore it.

Look instead for simple, single, open flowers with a visible middle. Good choices for a UK balcony or sill include:

• Lavender — English varieties such as 'Hidcote' are compact, hardy and flower for weeks in full sun. Bees of all kinds work them constantly.
• Rosemary — flowers early, often from late winter, when little else is out. It also copes with drought far better than most.
• Thyme, marjoram, oregano and sage — culinary herbs that earn their place twice over. Let some stems flower rather than picking every leaf.
• Borage — a fast annual with blue flowers that refill with nectar quickly. It self-seeds, sometimes enthusiastically.
• Salvia, catmint and wallflowers — long-flowering and happy in containers.
• Spring bulbs — crocus and alliums give queen bumblebees something to feed on as they emerge.
• Sedum and winter heather — late and early flowers that stretch the season at both ends.

Aim for two or three plants in flower at any one time from early spring to late autumn. That is far more valuable than a single spectacular flush in July.

Choosing pots and compost

Size matters more than style. A window box around 25–30cm deep holds enough compost to keep roots cool and damp, while a shallow tray dries out within hours on a sunny sill. Whatever you buy, check for drainage holes — if there are none, drill some or the roots will rot after the first heavy watering.

For compost, a peat-free multipurpose mix is a sensible default. It dries out a little faster than peat-based compost, so check it often, particularly in the first few weeks while the plants are establishing. If you are growing lavender, rosemary or thyme, mix in a couple of handfuls of horticultural grit or sharp sand to improve drainage; these plants hate sitting in wet soil.

Feed lightly. A slow-release fertiliser at planting is enough for most flowers, and herbs need barely anything. Overfeeding produces soft leafy growth and fewer flowers, which defeats the whole point. If you do feed, a liquid seaweed or tomato feed at half strength once a fortnight through summer is plenty.

A note on weight

Wet compost is heavy. On a balcony, check your tenancy or lease before hanging boxes on railings or walls, and fix brackets into solid masonry rather than relying on suction cups or thin hooks. Window boxes on upper floors should always be secured from the inside or with proper brackets, never balanced on the ledge.

Watering without drowning or drying out

Containers fail more often from water than from anything else. On a hot day, a small box can lose its moisture by early afternoon, and plants that wilt repeatedly stop producing nectar properly.

1. Check daily in summer by pushing a finger into the top couple of centimetres of compost. If it feels dry, water.
2. Water in the morning where you can. Less evaporates, and foliage has time to dry before evening, which reduces mildew.
3. Water the compost, not the leaves. Aim low and slow until it runs out of the drainage holes.
4. Empty saucers after half an hour so roots are not left standing in water.
5. Mulch the surface with a thin layer of gravel to slow evaporation and keep the compost off the leaves.

If you are away, group pots together in a shaded spot and stand them in a shallow tray of water. A plastic bottle with a pinprick in the cap, plunged neck-down into the compost, will trickle water in slowly for a day or two. Water-retaining granules help, but they are not a substitute for checking.

Position, wind and the seasons

Most bee-friendly flowers want sun, so a south or west-facing sill will give you the widest choice. Balconies can be windier than gardens, though, and a plant battered by gusts will flower poorly. If your spot is exposed, choose tougher options such as rosemary, thyme, lavender and sedum, and consider a low screen or a solid planter wall to break the worst of it.

North-facing boxes are not hopeless. Mint, chives and some salvias will flower in part shade, though you will get fewer blooms and should expect to water less often.

Through winter, terracotta can crack in a hard frost. Wrap pots in bubble wrap or fleece, move them against a sheltered wall, and raise them onto pot feet so they do not sit in standing water. Tender annuals such as borage are best treated as one-season plants and replaced in spring.

Keeping the box going

Deadhead regularly. Removing spent flowers pushes the plant into producing more, and every new bloom is another meal. Cut back straggly lavender after flowering, but leave the old stems on herbs such as rosemary until spring, as they protect the plant through cold weather.

Skip insecticides entirely. A window box does not need them, and most sprays will kill the very visitors you are trying to attract. If aphids build up, a strong jet of water or a squirt of diluted washing-up liquid usually sorts it. Leave a shallow dish of water with a few pebbles in it nearby for bees to drink from, and resist the urge to tidy away every fallen leaf — small hollow stems and dry corners are useful to solitary bees.

Wasps and hoverflies will turn up too. They are pollinators as well as pest controllers, and on a balcony they are no more of a nuisance than the bees. Stay calm, keep the box away from doorways and dining tables, and let them get on with it.

Start small and enjoy it

You do not need a perfect scheme. One deep box, a bag of peat-free compost and three plants that flower at different times will keep a surprising number of bees fed from spring to autumn. Plant it, water it properly, and then spend a few minutes watching. The first bumblebee to find your lavender will tell you everything you need to know about whether it is working.

Photo: Life in the Apple Garden 🍎 / Pexels