Jeffersonia dubia border

Plant of the Month April 2024


Spring started early this year with some record high temperatures in Toronto, followed by severe frosts. Luckily most of our bulbs just fall flat and then revive. I go round the garden looking for emerging shoots. Small reddish leaf tips and buds mark the start of Jeffersonia dubia in the second wave of spring bulbs.

Jeffersonia dubia 16 03 24 

Jeffersonia dubia 16.03.24.

Synonym:  Plagiorhegma dubium is the correct taxonomical name.

Common Name: Japanese Twin-leaf.

Cultivars: Jeffersonia dubia ‘Variegata’, Jeffersonia dubia ‘Dark Centers’, Jeffersonia dubia alba, Jeffersonia dubia ‘Flore-Pleno’.

Life Cycle: Rhizomatous herbaceous perennial.

Height: 20-30 cm. 

Bloom Time: April to early May in the Toronto area. Jeffersonia dubia early april

Jeffersonia dubia - early April. 

Jeffersonia dubia mid april

Jeffersonia dubia - mid April.

Jeffersonia dubia

Jeffersonia dubia - early May (Lilactree Farm).

Flower Colour & Size: Lavender-blue, up-facing, cup shaped, 3-5 cm across. Flowering stem 8-10 cm high, growing to 25 cm after petal drop. 

Jeffersonia dubia leaf 

Jeffersonia dubia - leaves.

Leaves: Long stemmed, reddish purple leaves emerging with the flowers, then dull green. Almost circular, with lobed edges, slightly cleft into two.

Jeffersonia dubia capsule 

Jeffersonia dubia - capsule splitting, showing seeds. 

Fruit: Several seeded capsule, dehiscing in June. Will self seed.

Range: Native to Korea, China, Russia. Much cultivated in Japan.

Habitat: Deciduous woodland. 


Light: Semi-shade to full shade.

Soil: Humusy soil, well drained, near neutral pH.

Water: Keep slightly moist.

USDA Hardiness: Zones 4-7b.

Jeffersonia dubia  

Jeffersonia dubia - with Sanguinaria,  Corydalis, Anemone and Scilla.

Companion planting: Other rock garden plants, early woodlanders, spring ephemerals: Sanguinaria canadensis, Corydalis, Anemone, dwarf Epimedium.

Propagation: From fresh seed: Sow at 20°C for 6 weeks, then place @ 4°C for 6 weeks. Slowly raise temperature to 10°C for 6 weeks. If there is no germination, repeat the cycle. Will self seed. Clumps may be carefully divided after flowering.

Native alternatives: Plagiorhegma (Jeffersonia) diphyllum. White flowered with leaves cleft into two. See POM Jeffersonia diphyllum.

Pollinators: Bees.



Text and images supplied by Anna Leggatt (Toronto Master Gardener)