Dianella caerulea is an upright lily-plant with a rhizome and flax-like leaves. It is highly variable naturally.
This cultivar is known as Dianella caerulea ‘John 316’ and is marketed as King Alfred.
Dianella spp. produce their leaves on a buried condensed rhizome, with some species exhibiting aerial stems with alternate to clustered leaves. In this cultivar, the leaves are arranged alternately on opposite sides of aerial stems with the lower part of the stem leafless; to 60 cm long, and to 2 cm wide, mid-green to lighter green. The bases of leaves are occluded – a feature where the two halves of the upper side of every leaf are folded lengthwise and seemingly glued together – a useful identification feature for this species combined with habitat (especially when it is not in flower). King Alfred has vivid red leaf bases with blue-green foliage and is a wide clumping plant.
Dianella spp. produce flowers on elevated inflorescences, usually above the foliage, which are described as cymose but have a panicle-like appearance. The individual flowers are blue to violet and are arranged in branches on the main axis. Flowers are bisexual with six tepals (three sepals and three petals which are almost identical – a typical lily-characteristic) and a superior ovary. In this cultivar, flowers are blue with yellow anthers and are borne on spikes to one metre high and are followed by globular bright blue-purple berries about 1 cm in diameter.
This plant grows well in full sun and moderately shaded positions. It tolerates salt laden windy positions and is very drought tolerant. It lives on natural rainfall in most of the populated areas of Australia. The maintenance requirements for Dianella is low, it will only need trimming approximately once every 5 to 8 years if at all. It is reported to be good for erosion control.
These plants grow quickly in pots and can quickly become pot bound in nurseries.
When this happens nurseries often place the plants on sale at a reduced price and this means a great bargain. However, you will have a few problems when you get the plant home.
The first problem will be to remove the pot, because the roots that have grown through the drainage holes will prevent you knocking the pot away from the root ball. You will need to cut the plastic pot away from the root ball to get it out of the pot.
Once this has been done, you can cut away two to 3 cms of old damaged roots from the bottom of the root ball and plant as normal. A better idea is to cut the plant in half (see photo 3), tidy up the cut leaves and roots, repot with new potting mix and water with a seaweed solution – two plants from one.
An even better suggestion, if you are game, is to cut it into four, clean up the cut leaves and roots, repot with fresh potting mix and again water with a seaweed solution – four plants from one. Being so hardy, they will quickly make new growth ready for planting out into the garden.
Must be propagated by division to retain ‘true-to-type’ forms. Divisions can be undertaken in Autumn with foliage then cut back when planted. Provide adequate water until established.
A benefit of Dianella, along with many other monocotyledonous plants, is they can be transplanted. This is best done in Autumn and Winter. Plants can be dug up and divided along the rhizomes and replanted. It is best to cut back the foliage by two-thirds if doing this and replant, where desired, quickly. The author has found this is the quickest way to establish a sizeable plant. Keep transplanted plants moist for a few weeks.
Dianella is a genus of 35-45 species of monocotyledonous flowering plants (which have been subject to family reclassifications in recent times). They are commonly known as Flax Lillies and are closely related to other native genera such as Thelionema and Herpolirion, as well as, more broadly to Xanthorrhoea and Lomandra. They are found from Africa, through south-east Asia, Australia, New Zealand and the wider Pacific to Hawaii. Australia has around 25 species, occurring in all states. The genus has much variation and there are likely more species which require formal descriptions. NSW currently has about 20 taxa – both formal and informal at this stage.
To view the list of Dianella species accepted by the World Checklist of Selected Plant Families as at October 2020, use this link: https://en.wikipedia.org/wiki/Dianella_(plant)
Fruit can be eaten raw or cooked and have a comparatively better taste than other species (Wild Food Plants of Australia, Author: Tim Low 1989).
Most Dianella plants will survive fire; regenerating quickly from rhizomes as well as any seedbank.
Dianella – Latin diminutive of Diana – the Roman Goddess of the hunt and wild animals, often associated with woodlands. The first specimen of this genus was collected from the island of Mauritius by French botanist-explorer Philibert Commerson (1727-1773) and was simply labelled “Diana”.
caerulea – Latin meaning “dark-colored”, “dark blue”, “cerulean”, “azure”, “sea-colored”, “sea-green” – likely referring to the flower colour.
‘King Alfred’ – exact reason for marketing name is unknown – assumedly referring to the 9th century king of the Anglo-Saxons.
OzBreed – King Alfred Dianella information page https://ozbreed.com.au/plant-ranges/strappy-leaf-plants/king-alfred-dianella/
Alpine Nurseries – King Alfred Dianella information page https://www.alpinenurseries.com.au/plant-library/dianella-caerulea-king-alfred/