The most attractive flowers for bees.

Planting flowers that attract bees will provide much needed food for pollinators near you, and can require as little space as a windowsill.
Bees need 3 things to thrive: food, shelter and water. Different bees are active throughout the year, so you'll need flowering plants from spring to winter.
From herbs and ornamentals to hardy winter bloomers, bees benefit from a plethora of plants. For bees, a garden can be made significantly more attractive by providing resources and small spaces that offer the bees places to rest, burrow or find shelter.
Single-headed flowers will provide the most nectar for honey bees, and brightly colored plants will act as signposts guiding bees to your garden. Cornflowers, aster, foxglove and sunflowers are all good flower choices, as are goldenrod, cosmos and bluebells. Plants like oregano, rosemary, lavender and mint can attract bees and other beneficial insects.
Trees and shrubs for bees: pussy willow, lavender, abelia, mahonia, apple or crabapple, hawthorn, honeysuckle, ivy.
Flowers for bees: lungwort, monarda, sedum, winter aconite, crocus, phacelia, perennial wallflower, snowdrop.
Herbs for bees: marjoram, chives, sage, rosemary.
Fruit and veg for bees: kale, strawberry, runner/broad bean, raspberry.
Wildflowers for bees: cowslip, viper's bugloss, white deadnettle, lesser celandine, comfrey, wood forget-me-not, yarrow, field speedwell.