Phacelia

Phacelia (Phacelia tanacetifolia) is an annual herb; the NRCS guide places it in the waterleaf family (Hydrophyllaceae). It grows 30–90 cm tall, with upright, succulent stems covered in short stiff hairs and finely divided, toothed leaves. The blue or purplish bell-shaped flowers open one after another along one side of the spike, so the inflorescence curls.

For bees it is a highly attractive source of quality nectar and pollen: the US Department of Agriculture's NRCS plant guide lists it among the top twenty pollen-producing flowers for honey bees. It is also on the list of species that can give unifloral honey in Europe, as the source of phacelia honey.

It is native to California and neighbouring Nevada and Arizona, where it blooms from April to June; in milder regions bloom lasts longer. Brought to Europe in the 20th century, it was domesticated as a forage and bee plant, cultivars were developed for European use, and it is now naturalised in Southern Europe. Here it is sown as a cover or catch crop. It prefers well-drained sandy or gravelly soil, tolerates drought but not waterlogging, and frost of about −8 °C kills it.

Why this matters to you: phacelia is sown, so a beekeeper can arrange with a farmer to have it planted next to the apiary; plantings for bees are cut only after bloom.