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Astelia - Bush Flax

How to grow successful bush flax (Astelia)

Words and Photos by Dylan Norfield

Words and Photos by Dylan Norfield

The bush flax or Astelia are not closely related to the betterknown flaxes, but are named for their superficial resemblance in appearance. Many of the species are so familiar when out tramping that we often don’t notice the different types as they blend into the bush areas or alpine flora. In fact, in New Zealand there are more than 13 different species ranging from the coastal lowland forests up to our snow-covered peaks and on the surrounding islands. They may not be the showiest of plants, but some selections are attractive and they have good merit for many locations in the garden at home.

The Astelias can tolerate a wide range of conditions due to the way they have adapted to all the different environments in which they grow. The key to growing successfully is to choose the right species for the right location. The consistent thing with all the species is that they are all pretty drought-tolerant and dislike constantly wet roots.

The roots are quite fleshy and, along with the slightly swollen bases to the leaves, can store water and sustain plants in prolonged periods of drought. Conversely, because they are fleshy they are prone to rotting and like good drainage. The most common means of killing Astelias is to over-water them.

When choosing a species for your garden consider size and purpose. The most common and widespread species is Astelia fragrans, which commonly grows in bush areas from the coast up to about 900m above sea level. Reaching up to 1.5m, it is good for woodland gardens, often being more architectural than a flax bush, but can also tolerate coastal areas. In windy coastal locations the leaves can become tatty and the green foliage will yellow slightly in full sun. A better choice for coastal locations is A. chathamica ‘Silver Spear’. The name is very apt as the 1m tall foliage often has a beautiful silver sheen, which is accentuated when grown in sunny locations. Looking at where it grows naturally gives us a good clue to the location it will like in the garden; it grows on the Chatham Islands where it experiences strong winds and full sun. As it grows near the coast it dislikes winter wet and cold so is not suitable for colder locations that experience frequent winter frosts.

In colder locations it is best to look towards the alpine species that are adapted to these conditions. Some of the most beautiful species and cultivars have originated from these species, especially from A. nervosa. A. nervosa is one of the most widely spread alpine species and due to this can vary in colour from area to area. The most noticeable characteristic of the species is often the silvery foliage contrasting with darker-red veins through the leaf. Even though naturally this species would experience frequent and high rainfall, it often grows on mounds, slopes or areas of good drainage. It is only a small species, to 50cm, and looks good when planted as a group or to frame an area.

Several excellent cultivars have been selected for leaf colour, with one of the best being A. nivicola ‘Red Devil’. When grown in full sunlight it develops dark bronze foliage, being lighter in colour when grown in the shade. Propagation of species, dare I say, is easy. Division of existing plants is straightforward as if carrying out herbaceous division. Each year as they grow they develop pups around the outside of the existing crown of leaves. Once these have grown for a couple of years they form their own roots and can be easily pulled away from the parent plant. This is achieved best with plants grown in pots as the whole plant can be knocked out and the pups teased off, but if in the ground, dig around one side of the plant to expose the roots and again tease off the baby plant. The new plant is best potted up into a good potting mix and maintained in a pot for a year until new roots have established.

Though much slower, propagation by seed is also achievable and is good for producing large numbers. Fruits are produced on spikes from the centre of the foliage in autumn. These fruits are often an attractive orange colour and a feature in themselves. These little fruits contain numerous black seeds that need to be separated and sown just under the surface of a good seedling mix. Germination can be very slow, so be patient.

19 August 2018