Phacelia

Phacelia, Phacelia tanacetifolia, is an annual herbaceous plant reaching a height of between 50 and 120 cm. It originates from California and Mexico and was introduced into Europe in the 19th century. It occurs near dwellings and on wasteland, where it can even become invasive; however, it is mainly cultivated as a green manure, as a forage crop, or as an intermediate crop.

The blue flowers are grouped at the top of the stem, which has the distinctive feature of curling like a scorpion’s tail; the flowers open over successive days as it unfurls, thereby extending the period during which bees can visit. The leaves are divided into numerous toothed lobes, similar to those of tansy (Tanacetum vulgare), from which the plant’s scientific name is derived.

Phacelia is very easy to cultivate and can be sown in the garden, for example along the edge of a vegetable plot. Staggered sowings throughout the season, between May and September, allow for continuous flowering that is highly appreciated by bees. It is recommended to cut the plant after flowering, avoiding pulling out the roots, which, as they decompose, enrich the soil thanks to the nitrates that the plant has captured from the atmosphere and fixed in the roots.

Phacelia is among the plants selected under the “Bee Action Plan” established by the Swiss Confederation, which aims to protect bees and encourages the establishment of “flower-rich meadows” as rotational crops.

It produces very abundant and highly sugary nectar, making it one of the most melliferous plants. Bees also actively collect the pollen, which is of particular interest in autumn when other sources become scarcer; blue in colour, it forms very distinctive pollen pellets.

From the nectar of the beautiful mauve flowers, bees produce a pleasant honey; however, it is not possible to harvest a pure phacelia honey in Switzerland, as is the case in certain regions of France, for example, because the cultivated areas are not extensive enough or because flowering occurs too late. This monofloral honey, greenish in colour, is highly aromatic and crystallises finely. More frequently, phacelia nectar forms part of mixed-flower honeys. (Isabella Moretti)

Sources

Silberfeld, C. Reeb, Les plantes mellifères, 2016

Piquée, Les plantes mellifères mois par mois, 2014

Bieri, Pollen analysis of the BIP (Biologisches Institut für Pollenanalyse), 2016

Swiss monofloral honeys, Alp Forum 2005, No. 23f (reprint 2008)

Various authors, Le traité Rustica de l’apiculture, 2002

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