A courtyard, a balcony, a narrow strip behind the bins — none of these look like wildlife habitat at first glance. But wildlife is remarkably opportunistic. Give a bumblebee a reliable source of nectar, a frog a damp corner, or a sparrow somewhere safe to drink, and they will find it. Small gardens, done thoughtfully, can be richer than a manicured lawn ten times the size, simply because every centimetre is doing a job.

The trick is to think in layers and aim for three things: food, water and shelter. Get those right in even a few square metres and you will notice the difference within a single season.

Start With Flowers That Actually Feed Wildlife

Not all flowers are equal. Double blooms, however pretty, often hide their nectar behind layers of petals so bees cannot reach it. Single, open flowers are the ones that pay.

Native and near-native plants are your best bet, because local insects have evolved alongside them. Try:

• Foxgloves and common knapweed for bumblebees — both are happy in pots and tolerate a little shade.
• Lavender, wild marjoram and catmint for a sunny sill or border; they flower for months and smell wonderful.
• Bird's-foot trefoil, a low-growing native that suits a gravel patch or the edge of a pot and feeds several scarce bee species.
• Ivy and honeysuckle for autumn and evening moths — ivy flowers late, when almost nothing else is open.

Aim for something in bloom from March to October. Three or four generous pots will beat a dozen scattered ones, because insects prefer to feed in bulk rather than flit between lonely blooms.

Water: The Cheapest Life You Will Ever Add

Every creature in your garden needs water, and a shallow dish does the job beautifully. Use a saucer or glazed pot base around 30cm across, no more than 5cm deep, and sink it into a border or stand it among pots so it sits at ground level.

• Add a few pebbles or a piece of broken slate, so bees and hedgehogs can climb out — drowning is the biggest killer of garden wildlife.
• Refresh the water every other day in summer to stop it going stagnant.
• Place it within a metre of a shrub or hedge, so birds feel safe while they drink.
• Raise a second dish on a wall or railing for birds, and keep it well away from anywhere a cat can crouch.

If you have room for nothing else, do this. A bee drinking from a saucer on a hot July afternoon is a genuinely cheering sight.

A Log Pile Is a Five-Star Hotel

Dead wood is one of the most underrated habitats in Britain. A modest pile — say 60cm high and a metre long — will be colonised by beetles, fungi, solitary bees and hibernating frogs, and it costs nothing if you ask around for prunings.

• Keep the bark on and mix sizes, from thick branches down to thin stems.
• Site it in shade, ideally where the ground stays slightly damp, and partly bury the bottom logs.
• Leave it alone. A log pile is meant to rot — that is precisely the point.
• In a tiny space, use an upright bundle of hollow stems instead, or drill holes 8mm wide and 10cm deep into a block of untreated wood and mount it south-facing, a metre or so up.

Grow Upwards and Make Every Wall Work

Once the floor is taken, go vertical. Walls, fences and railings absorb heat through the day and radiate it at night, which makes them superb places for sun-loving plants and basking insects.

• Fix trellis or wire to a sunny wall and grow a climbing rose, jasmine or native honeysuckle.
• Hang three or four wall planters at staggered heights — herbs, trailing nasturtiums and sedums all thrive.
• Stack pots in tiers or use a shelving unit; bees will happily work a vertical garden as long as the flowers are open to the sun.
• Leave a small patch of bare soil or gravel somewhere. Ground-nesting solitary bees need it, and so do dust-bathing birds.

Resist the Urge to Tidy Up

The single biggest mistake in wildlife gardening is autumn cleaning. Seed heads feed goldfinches through the winter, hollow stems shelter overwintering insects, and fallen leaves make a larder for blackbirds and song thrushes.

So leave the seed heads on your teasels and sedums until late February, let a corner of leaf litter accumulate, and skip the pesticides entirely — a few aphids are simply bird food in waiting. If you grow in containers, choose peat-free compost and top-dress with homemade compost or well-rotted manure each spring.

None of this needs a big budget or a big garden. A saucer of water, three good flowering pots, a bundle of hollow stems and a decision not to tidy quite so keenly will turn the smallest courtyard into somewhere genuinely alive.