Why the first warm days matter so much

By the time the first genuinely mild afternoon arrives in late February, the bees in your garden have already been through the hardest part of their year. Queen bumblebees that mated last autumn are waking from hibernation in the soil, and they have no workers to help them. Each queen must find nectar immediately to fuel her flight, then pollen to provision the first cells of a brand-new nest. If she fails in that first fortnight, an entire colony disappears.

Solitary mining bees are emerging at the same time, and honeybee colonies that have survived the winter are beginning to rear brood in earnest, which means an appetite that a few straggling winter flowers cannot meet. This is the gap that catches gardeners out. Everything we plant for summer is still dormant, and the result is a genuine famine. The remedy is straightforward: put in a small group of plants that flower when nothing else does.

Willow: the single best tree you can plant

If you only make one addition, make it a willow. Goat willow (Salix caprea) and grey willow (Salix cinerea) produce their fat, silver catkins from February into March, and they offer both nectar and pollen in quantity. A mature sallow in a sunny spot is one of the most valuable wildlife trees in Britain.

Willows are dioecious, meaning male and female flowers grow on separate trees. Male catkins are the ones that go golden with pollen; females produce the richer nectar. If you have room for two, plant one of each and you will feed bees for weeks. If space is tight, Salix daphnoides, the violet willow, is a fine smaller choice with purple young stems.

• Plant in moist soil, ideally near a pond, ditch or downpipe; willows hate drying out.
• Keep them well away from drains, foundations and sewer runs, as the roots are famously thirsty.
• Coppice or pollard on a rotation, but never cut a willow in late winter — you will remove the very catkins you planted it for. Cut in spring after flowering, or in midsummer.
• Always leave at least one mature branch to bloom each year.

Crocus: the corm that carries early spring

Crocus are the reliable bridge between willow and the later spring flush, and they are far tougher than their delicate looks suggest. Crocus tommasinianus is the best of the bunch for bees, flowering from late February and seeding about freely once settled. Crocus chrysanthus follows close behind, and the large Dutch crocus (Crocus vernus) extends the season into April.

Plant corms in September or October, roughly 7–8cm deep and 8cm apart, in full sun and sharply drained soil. Crocus rot in heavy clay, so work in grit or plant them on a raised bank or in a gravel garden. They naturalise beautifully in short grass, where they will multiply into drifts over the years.

The crucial rule with any bulb in grass is to leave the foliage uncut for six weeks after flowering. That greenery is feeding next year's corm. Resist the urge to mow, and you will have more flowers every spring. Skip the double-flowered varieties entirely: they look extravagant and offer bees almost nothing.

Hellebores: nectar in the worst weather

Hellebores flower in conditions that would keep most sensible insects indoors — cold, damp, grey — and bumblebee queens will still work them on any day warm enough to fly. Helleborus niger, the Christmas rose, can open in December. Helleborus foetidus and Helleborus argutifolius follow in late winter, and the orientalis hybrids carry on into April.

The nodding flowers look closed, but they are built for bees: the queen pushes her way in and comes out dusted with pollen. Plant them in dappled shade with plenty of leaf mould, and give them a year to settle. Cut back tatty old foliage in December or January as the flower buds appear, which makes the blooms visible and helps limit hellebore leaf spot.

Building a nectar ladder

Together these three cover roughly February to April. Fill the gaps with pulmonaria, mahonia, winter honeysuckle, deadnettle and the humble dandelion, and you will have an unbroken supply from the first mild day to the fruit blossom.

• Plant in clumps, not singly. Bees find a large patch far more efficiently than scattered individuals.
• Give shelter and warmth. A south-facing wall, a sunny bank or a strip of paving that holds heat lets queens forage when the air is still cool.
• Remember that daffodils, however cheering, produce no usable nectar. They are decoration, not food.
• Leave a few patches of bare, sunny soil and some old logs; bumblebee queens nest in abandoned rodent holes and tussocky grass.
• Never spray insecticide on a plant in flower, and keep shallow water available — a saucer with pebbles and a few stones will do.