Common names for this species include the ‘Chilean Hard Fern’. The Chilean Spanish name for the species is ‘Costilla de vaca’ which literally translated means ‘cow’s rib’ referring to the shape of the fronds. The name ‘chilense’ refers to is origins from Chile. The species can be found growing at both low and high altitudes in Chile, plants growing at higher altitudes tend to show more coloration in emerging fronds. Blechnum chilense often colonizes alongside roads, as it is quick to establish after land clearance or disruption to the land.
The fronds of Blechnum chilense can grow over 100cm (3ft) in length. With juvenile fronds having an orange-rusty glow to them, once mature fronds have a waxy dark green appearance. The species is dimorphic. With fertile frond standing erect frond the centre of the plant from late spring onwards. As the plant establishes multiple growth points or crowns can establish from the plants rhizome. The oldest of these crowns will produce a short trunk measuring just a few inches in height.
There is a debate currently as to whether Blechnum cordatum which is found in the cloud forests of Columbia, Peru, Venezuela, Bolivia, and Ecuador is the same as Blechnum chilense which grows just a few hundred miles away in Chile. The two are often mixed up when grown commercially and the more common ‘chilense’ is often sold as ‘cordatum’.
Blechnum chilense is fairly hardy and has survived temperatures down to -10°C (14°F) in my own garden in Southern England. During the winter of 2010/2011 when temperatures went down even further the plant did survive, but it wasn’t until mid summer that new fronds began to emerge from the rhizome underground. This would suggest that temperatures much lower than -10°C of where snow has been lying on the ground for several days may cause problems. Therefore it may be sensible to use leaf mulch around the crowns of these plants if you experience regular hard winters. Blechnum chilense has naturalised in the UK and there are around 30 sites where the species can now be found in the wild. Blechnum chilense is one of the most common and easiest of the Blechnum family in mainstream cultivation to grow, making it a worthy addition to any garden.