The phacelia is an annual, undemanding plant, which is an excellent bee pasture and is also sown in the garden and in organic farming as a green manure plant. It is much taller than its relative desertbells (Phacelia campanularia), which has heart-shaped, feathered, but marginally sawn leaves and bell-shaped, blue flowers. In contrast, the flowers are more reminiscent of the flower heads of thistle-like plants.
Profile of phacelia:
Scientific name: Phacelia tanacetifolia
Plant family: borage family (Boraginaceae), waterleaf subfamily (Hydrophylloideae)
Other names: lacy phacelia, blue tansy, purple tansy
Sowing time / Planting time:
Flowering period: June – October
Location: sunny to partially shaded
Soil quality: no special demands
These information are for temperate climate!
Use: cottage garden, flower garden, vegetable garden, natural garden, rock garden, flowerbeds, bouquets, flowering meadows
Winter hardiness: hardy
Bee and insect friendly: very much
Plant order, origin and occurrence of phacelia
Phacelia (Phacelia tanacetifolia), also called blue tansy or purple tansy, belongs to the approximately 200-species rich genus of Phacelia, which is counted among the borage family (Boraginaceae). It is native to the dry altitudes of California, Arizona and Mexico to 2,000 meters altitude (6,000 feet). There it occurs naturally on roadsides and fields. Since the beginning of the 19th century the blue tansy is cultivated as an ornamental plant.
Characteristics of phacelia
Phacelia is annual and grows herbaceous and upright. The fluffy hairy stems are about 70 cm (28 inches) high. Its dense root system organically enriches the soil, loosens it and helps against soil fatigue. The annual plant dies at temperatures below minus six degrees Celsius.
Unlike the stems, the fern-like pinnate leaves of blue tansy are hairless. They are alternate and are arranged spirally around the stem axis.
Caution: Contact with the leaves may cause skin irritation.
The phacelia shows its filigree tubular blue flowers from June to the first frost. Pistil and stamens overtower the petals and are so easy to reach for insects. Shortly before finish blooming, the inflorescences often spiral outward. The flowers are a rich source of pollen and nectar for bees, bumblebees, butterflies and hoverflies.
The warty-shriveled seeds of the dark germinator sit in two-columned capsule fruits, which bounce when touched.
Phacelia – cultivation and care
Phacelia grows best in a full sun to a half shade position.
It has no big claims to the soil. Only on permeability is to be respected, since the plant does not tolerate waterlogging.
Phacelia can be sown in mild locations as early as March, otherwise at the end of April directly into the bed about one to cm (0.4 to 0.8 inches) deep. At 12 to 18 °C / 54 to 64 °F, the seeds germinate within 14 days. Since the plant is sensitive to cold, one should wait with the sowing, until no further frosts impend.
Phacelia is quite drought-tolerant and does not need much care. Only during the growth phase sufficient irrigation should be guaranteed. Once a month, you can provide the plant with some fertilizer to keep it bloom. To avoid self-sowing, the plant should be cut before fructification.
Phacelia is annual and proliferates by self-sowing before it dies at the first frost. For selective sowing, the seeds can be collected during ripening and re-used next spring.
Diseases and pests
Both against diseases and against pests, the plant is insensitive. Phacelia protects other plants from nematodes and clubroot.
Use in the garden
In the bee-friendly garden Phacelia finds its place in the dry perennial flowerbed or in the rock garden next to ornamental grasses and other annuals. The flower grows best in small groups. The flower can also be grown as a container plant.
It is popular as a green manure plant, as well as beekeepers like to plant it. The amount of nectar and pollen is similar to rapeseed or buckwheat. Last but not least, blue tansy is used as an easily digestible feed, for example in pig fattening. Although the tall stems are well suited as cut flowers, but since they are allergenic, be careful when giving away.
Especially for the large-scale agricultural green manure various vigorous and robust Phacelia tanacetifolia varieties have been developed such as ‘Lisette’, ‘Angelia’, ‘Balo’, ‘Julia’ and ‘Gipha’.
Phacelia has established itself as a green manure plant due to its special properties. It is not related to any domestic vegetable species and therefore fits easily into the crop rotation. A green manure acts like a small soil cure. For example, if you leave vegetable beds open in winter, the floor will dry out and become encrusted. The sowing of green manure plants protects the earth.
The plant should be sown as green manure between September and October with a row spacing of 10 to 15 cm (4 to 6 in). In December, the stems are then cut off, the cabbage remains on the beds. In the spring you work the remaining plants while breaking up the ground. This produces important humus. The following vegetables benefit from the deeply loosened, nutrient-rich soil.
Your recommended seeding time is after native populations are done blooming. What do you recommend for sunset zone 10 – Apple Valley, CA.
In this case, you should go with the temperature given. 54 to 64 °F. Whenever it is not freezing anymore (if at all in your region), you are good to go.