Why late winter is the hungriest time in the garden

By the middle of January, most of our gardens have gone quiet. The last of the ivy flowers have finished, the winter honeysuckle is hanging on by a thread, and the first queen bumblebees are already waking from hibernation and hunting for something to drink. A bumblebee queen emerging on a mild, sunny day in February needs nectar within minutes of leaving her burrow, and if she cannot find it she may never manage to establish a nest at all.

This is where bulbs earn their keep. A handful of species flower when almost nothing else is open, and they do it repeatedly, year after year, with no fuss. Plant them now, while the soil is still workable, and you are effectively laying a table for the earliest pollinators in your neighbourhood.

Get the timing right and your border will be humming from late January through to April, long before the first hardy annuals have even been sown.

Three bulbs worth planting for early pollinators

Crocus are the workhorses of the early season. Choose Crocus tommasinianus varieties such as 'Ruby Giant' or 'Whitewell Purple', which open in February and are far less appealing to squirrels than the larger Dutch crocus. They produce pollen as well as nectar, which matters enormously to solitary bees and honeybees on their first cleansing flights. A single corm can open five or six flowers, and each flower offers a proper feed.

Snowdrops are the other pillar of the winter garden. Most are happiest in light shade under deciduous shrubs, where the soil stays cool and moist. They are best bought and planted in the green in late February and March, lifted as growing plants rather than dry bulbs, which shrivel quickly and resent being out of the ground. Honeybees and the occasional early bumblebee will visit them on any day the temperature creeps above about 8°C.

Snake's head fritillary (Fritillaria meleagris) takes the baton into April. Its nodding, chequered bells are a native speciality of damp meadows, and they are superb for queen bumblebees emerging from hibernation. Plant the bulbs in autumn, around 10cm deep and 10-15cm apart, in soil that never fully dries out. They will bulk up slowly into generous colonies if they are left undisturbed.

How to plant for a display that actually feeds insects

Bulbs are forgiving, but a few specifics make the difference between a scattering of flowers and a proper wildlife resource.

• Depth: as a rule of thumb, plant each bulb at roughly three times its own height. Crocus corms go 5-8cm deep, snowdrops 10cm, fritillaries 10-15cm.
• Spacing: 5-8cm apart for crocus and snowdrops, 10-15cm for fritillaries. Closer planting looks better and holds each other upright in wind.
• Drainage: crocus hate sitting wet. Fork the bed over, add a handful of horticultural grit to the base of each planting hole, and never let them stand in a puddle.
• Sunlight: crocus only open properly in full sun, and the flowers close on dull days, so give them the brightest spot you have. Snowdrops and fritillaries will take light shade.
• Protection: squirrels and mice dig up crocus corms with enthusiasm. Plant them deeper than you think necessary, lay a sheet of chicken wire just below the surface, or tuck them into rough grass where digging is less tempting.

Plant in drifts, not lonely singles

Pollinators are practical creatures. A single crocus is easy to miss and offers a poor reward for the energy spent flying to it; a drift of thirty is a beacon. Aim for groups of at least twenty-five to thirty corms of a single variety, planted in irregular, river-like shapes rather than neat circles. Repeat the same variety in two or three places across the garden so that a bee working one patch does not have to travel far to find another.

If you have a lawn you are willing to let go slightly wild, crocus and fritillary naturalise beautifully in grass. Under a deciduous hedge, in the strip beneath a fruit tree, or along the sunny edge of a shrub border are all ideal. Winter aconite is a lovely companion, though it is best planted in the green alongside snowdrops.

Caring for the bulbs after flowering

The single most important job is to leave the foliage alone. Those leaves are the factory that builds next year's flower, and cutting them down too soon is the commonest reason bulbs dwindle to nothing. Wait at least six weeks after the last flower fades, until the leaves have yellowed and flopped, before you tidy them away. If the bulbs are in grass, that means no mowing that patch until June.

A light dusting of general-purpose fertiliser or a handful of wood ash in early spring helps them build reserves, and a mulch of leafmould over the dormant bed in autumn keeps the soil in good heart. Divide congested clumps of snowdrops only while they are in the green, never as dry bulbs.

A word on hedgerows, foraging and wild bulbs

The bulbs flowering along a hedgerow bank in February are almost always garden escapees or long-established plantings, and they are a genuine lifeline for wildlife. Enjoy them, photograph them, count the bees working them, but please leave them where they are. Lifting wild bulbs damages the colony and, in the case of fritillaries and snowdrops, it is both illegal and pointless, as they rarely survive the move.

Do remember, too, that snowdrops, daffodils and fritillaries are all toxic and must never be eaten. If you are foraging in earnest, wait for the wild garlic and three-cornered leek of March and April, and always pick from abundant, healthy stands well away from roads and footpaths. The spring bulbs are for the bees, not the pot.