Mahonia species commonly known as the Oregon Grape are RHS listed as a shrub for UK wildlife. That's my focus for the HPS, the environment and nature linking with the plants.
Continuing from the interesting article (James Miller): autumn journal, Shrubs Revisited, and my Skimmia blog, let's move onto Mahonia, of which comprises 70 species largely form North/ Central USA, Eastern Asia. There's some good professional labelling/ identification at the Lakeside, (but not all of the plants and shrubs) I suspect this Mahonia could be M - bealei,?
Mahonia belong to the family: Berberidaceae, research now places Mahonia within an expanded Berberis genus. I focused upon Mahonia in an article last year for (Hort Week) and how this architectural shrub compliments others in the Courtyard Garden at the Lakeside.
The fragrant yellow flowers are formed dense/ upwards, comprising spreading sprays of inflorescences on a terminal clustered raceme, forming a paniculate spray/ spire. The individual flowers are small and highly numerous arranged closely along the stem of the raceme, comprising 6 yellow sepals and 6 petals, also known as Petaloid Sepals.
These acid - loving shrubs thrive in shade and are drought tolerant, preferring a well-drained humus rich soil, Mahonias will also handle heavy clay soil making them pretty bomb proof, (great for wildlife gardens)
The fragrant yellow flowers provide a vital source of nectar and pollen for bumblebees and other pollinators through late winter and early spring.
Once flowered, on any older shrubs that require pruning, I take the loppers/ pruning saw, and hard prune the leggy stems comprising the sprays/ rosettes of flowers, hard back to lower growth. This forms a more compact shrub and increases flowers and quality for the following winter; it also increases the quality and life of each individual shrub.
I've undertaken a good number of cuttings of Mahonia which have a good success rate for rooting potential. Semi ripe cuttings from mid-summer - autumn, using current seasons growth. Cuttings should be approximately 10- 15 cm long, and this year I'm going to insert them into a medium of grit sand and perlite as a trial, into 2 litre pots, about 3 - 4 cuttings to a pot to initiate roots in a cold frame or cool glasshouse for spring.
I'll also trial collecting the blue/ black berries during late summer/ early autumn, clean away the pulp, which research suggests will inhibit germination if not separated from the seeds, and sow into modules of seed compost for stratification within the cold frame or unheated glasshouse, with a view to spring germination. I've never tried this method of propagation with Mahonia, and so it will make for an interesting trial.
Kevin Line is Head Gardener/ Plantsman, Lakeside Hotel, Cumbria.
Member of Professional Gardeners Guild and also writes a blog on wildflower species for Lancashire Wildlife Trust.
