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Plant of the Month January 2024


Mahonias were not on my garden lists when I was young. “Oregon grape” was a poor substitute for holly in England. Our neighbour here in Canada had a bed filled with Mahonia  aquifolium beside her front door, facing north and east. It was dull dark green all year with a bronzy tone in winter and a few yellow flowers in early spring. Garbage blew in and was difficult to remove. Our present neighbours axed it. However, I remember Thelma as it gave us a very attractive seedling in our front bed. 

Mahonia Pinnacle March

Mahonia x wagneri ‘Pinnacle'. Early March.

Mahonia x wagneri ‘Pinnacle' is a splendid hybrid between Mahonia aquifolium and Mahonia pinnata.

Synonym: Berberis aquifolium ‘Fascicularis', Mahonia pinnata 'Pinnacle' and Mahonia aquifolium ‘Fascicularis’.

Common Name: Oregon Grape ‘Pinnacle’, Oregon Holly Grape.

Other Cultivars: Mahonia aquifolium ‘Apollo’ is similar. Mahonia aquifolium ’Smaragd’ is shorter.

Life Cycle: Upright, evergreen shrub which may produce suckers.

Height: 1.5 m, slow growing.

Bloom Time: Late April, early May in Toronto.

Mahonia x wagneri ‘Pinnacle' - Flowers - Early May.

Mahonia Pinnacle Inflorescence

Flower Colour & Size: Tiny yellow flowers in dense racemes at branch tips before the new leaves appear. The flowers are up to 1 cm long and look like tiny daffodils.

Mahonia Pinnacle early May

 Mahonia x wagneri ‘Pinnacle' - close up.

Leaves: Compound leaves with 5-11 leaflets pinnately arranged, holly like. They are thick, shiny, dark to mid green with spiny teeth. Young leaves are bronze-yellow with reddish petioles. Winter colour is dark green to reddish bronze. The old leaves fall in the spring.

Mahonia Pinnacle late May

 Mahonia x wagneri ‘Pinnacle' - young leaves - Late May.

Fruit: Sour, dark bluish-black berries with thin grey frosting.

Mahonia Pinnacle Fruit

 Mahonia x wagneri ‘Pinnacle' - berries - July.

Range: Mahonia aquifolium is native to north and central America.

Habitat: Mixed coniferous woods.


Light: Shade, semi-shade or even full sun with adequate moisture.

Soil: Any good well drained garden soil.

Water: Well drained, moist soil.

USDA Hardiness: Zones 5-8.

Companion planting: In the front of a shrub border or in the back of a rock garden. With spring bulbs.

Propagation: From seed: Expose to fluctuating outdoor winter temperatures with freezing for 3 months. Gradually increase light and temperature in the spring. Pulpy coat inhibits germination. Remove by soaking and rinsing in clean water for approximately 7 days. Discard water and wash off pulpy coat completely in daily detergent washes. Hybrids will not breed true from seed. From cuttings: Semi-ripe in late summer. Division of suckers.

Pruning: Cut back or thin as necessary after flowering.

Pests and diseases: Deer and rabbit resistant. Usually trouble free. Mildew and rusts might occur.



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