Mahonia eurybracteata ssp. ganpinensis threadleaf mahonia, Oregon grape

Ganpinensis is a threadleaf mahonia subspecies with the narrowest leaves. There is an assumption that it might be the identical plant to the American variety SOFT CARESS selected by Karen Reiter Stever. She claims that she found it among many seedlings of unnamed mahonia sp. in 2001 and selected it primarily for its unique thread-like foliage, a characteristic that is not known to exist in species and cultivars of Mahonia known by then. Could it be that she was not aware of this Chinese subspecies? In any case it is a beautiful plant worth introducing.

It bears evergreen leaves, only some 1 cm wide, leathery yet soft to touch, glossy, dark green when mature and copper orange as they emerge. They form loose fronds on an airy shrub. In autumn unroll 10-20 cm tall, upright racemes composed of small, bright yellow, fragrant flowers. If pollinated, they are followed by purple blue, edible berries that taste like barberry berries. If the autumn is cold, flowers wait with opening until warmer parts of late winter or spring.

It grows moderately into a dense shrub about 1.5m tall and wide. It loves a bit of sun and midday shade, or partial shade all day long. Plants grown in full sun set more flowers but are prone to sunscorch in colder climates. Still, they regenerate readily after spring pruning. This mahonia will be a jewel among other large-leaved evergreens and a fine-textured understory of mid-sized trees providing filtered sunlight.

Threadleaf mahonia requires fertile soil of any pH (acidic, neutral, and alkaline). It likes constantly moist but well-drained soil. We experienced the best results with acidic soil where its foliage produced the richest colour. It does not like drought so keep it mulched all year long. Its hardiness has been tested to -18 °C (USDA zone 7) so far, and we continue with hardiness trials as we believe it might take a few degrees lower.

Last update 09-10-2023