Southern Magnolia ‘Gallisoniensis’ · Magnolia grandiflora ‘Gallisoniensis’

This cultivar reaches 15 to 20 metres in height with a spread of 8 to 12 metres, forming a dense pyramidal crown that broadens with age. The persistent foliage is large, thick, and glossy dark green on the upper surface, with a distinctive rusty-brown indumentum beneath. The combination of leaf size, density, and year-round retention makes it effective as a visual screen or as a structural element in formal compositions. Solitary white flowers, cup-shaped and fragrant, open from June through August and can measure up to 25 cm across.

As a European-origin selection within the species, 'Gallisoniensis' has a long track record in southern European horticulture. The species tolerates a range of soil types, including acidic, sandy, and clay substrates, provided drainage is adequate. It performs well in full sun and accepts partial shade. In urban Lisbon, where reflected heat and mild winters prevail, established specimens tolerate summer conditions without supplementary irrigation. In the humid Minho and Douro valleys, including Amarante where Diaplant grows this cultivar in open field (cultivado em pleno solo), adequate rainfall and mild winters suit it well, though the dense crown and persistent litter should be considered when specifying near paved surfaces.

In the Algarve and interior Alentejo, where summer temperatures regularly exceed 40 degrees C and annual rainfall drops below 600 mm, an establishment irrigation programme is advisable. The species shows high heat tolerance but only moderate drought tolerance once water stress is prolonged. Low salt tolerance limits its use in exposed coastal sites with direct salt spray. It tolerates urban pollution, which supports specification in metropolitan settings in Greater Lisbon and Greater Porto.

Maintenance requirements are moderate. Formative pruning establishes a clean single stem where needed; without intervention, branches persist to ground level. Leaf drop is continuous, and the large leaves create persistent litter on hard surfaces. Disease and pest resistance is good under Portuguese conditions. Expected useful life in an urban setting exceeds 80 years where soil volume and water availability are adequate.