Fool’s Onion

Credit: Richard Hebda

As is typical for the species in the genus, fool’s onion arises from a fingertip sized flattened corm.

A pale-brown fibrous tunic clothes the corm and extends up the stalk. One or two grass-like leaves emerge, reaching to 40 cm (16 in.) long but only about 1 cm (1⁄2 in.) wide. These remain green until the time of flowering, when a long green stalk up to 70 cm (28 in.) high rises from the corm. On south Vancouver Island flowers open in June, in cooler sites lasting just into July. Often 30 or more of them cluster into a modestly tight group at the top of the stalk. Usually about half the individual blooms are open, while the rest form attractive pointed buds or have passed to capsule stage. Oval petals and sepals look similar, both a whitish colour, sometimes pale blue. A prominent bluish-green mid-vein neatly marks each segment of the flower. Flower segments are joined near the base to form a bit of tube. The related harvest brodiaea (Brodiaea coronaria) has fewer but bigger blooms with violet-purple petals and resembles the widely available Brodiaea laxa (sometimes listed as Triteleia laxa and also called Ithuriel’s spear; usually sold as ‘Queen Fabiola’ cultivar). The six stamens of fool’s onion form a most interesting structure with their bases fused about halfway along.

A single green pistil occupies the centre of each 2-cm-wide (3⁄4-in.) flower. In B.C. you will encounter fool’s onion on southeast Vancouver Island and the adjacent mainland. The geographic range extends southward to California and east to Idaho and Nevada. In the wild the species grows in grassy meadows, rocky flats and sometimes in sunny openings in woods. It’s found mostly at low elevations but in the southern part of its range reaches into mountain meadows. East of the Cascade Mountains in Washington and Oregon it is a common plant of sagebrush desert, testimony to its drought resistance. Fool’s onion is easy to grow. I began my patch with corms rescued from a construction site. I planted them about 7.5 cm (3 in.) deep in a south-facing terrace of a rock garden that is mostly in full sun with shade in the afternoon. Some authors recommend planting this group of plants up to 12.5 cm (5 in.) deep. A well-drained site is required, one that never gets waterlogged. Little or no watering is best in the summer. Plant the corms in clusters of 10 or more if you desire a focal display. But as in nature, fool’s onion shows off just fine as scattered white flowerheads nodding among other grassy plants. The best thing about this species is that you can leave it in the ground for years with no need to divide it.

I mulch mine in the winter with a thin layer of leaf mould or chipped garden debris. If necessary, corm clusters can be divided in late summer and early fall before the rains return and individual corms replanted about 10 cm (4 in.) apart. Fool’s onion can be grown from fall- and spring-sown seed in porous, gritty soil. Unfortunately it is subject to damping-off disease if not grown in a ventilated setting. Although, in general, the plant looks like a blooming onion, it does not have the typical onion odour when crushed, hence the common name. Apparently some observer saw a resemblance to a hyacinth in the flowers and derived the species name and an alternate common name, hyacinth brodiaea.

There are no recorded aboriginal uses, but the corms are reputedly edible raw or cooked as an emergency food. This fall when you check out the bulb offerings, go the extra distance and search for a native species to include with the standard fare. For a summer-dry site and early-summer bloom, fool’s onion is a reliable choice. The following plants are hardy to the zone number indicated: • Brodiaea coronaria (harvest brodiaea) – zone 8 but reported as low as zone 5 • Brodiaea hyacinthina (fool’s onion) – reported as zone 4 but 5-6 is more realistic • Brodiaea laxa (Ithuriel’s spear) – zone 6 An expert on native plants, Richard Hebda is curator of Botany and Earth History at the Royal British Columbia Museum in Victoria.