Borage

If you grow one plant for the bees, grow borage. It produces vivid true-blue star flowers from June to October and refills them with nectar at such a rate that it is reckoned among the most valuable bee plants you can sow. On a warm day a borage plant fairly hums.

It is as useful in the kitchen as in the border. Flowers and young leaves both taste distinctly of cucumber, and the blue stars are one of the loveliest edible garnishes there is — floated in a jug of Pimm's, frozen into ice cubes, scattered over a soft cheese. The flowers open pink and turn blue, so a single plant carries both shades at once.

It actively prefers poor soil and full sun, and rich ground simply gives you lush leaf and fewer flowers. Sow it where it is to grow, since the taproot resents moving, and let a few heads set seed — one sowing usually means borage for years.