The latest newsletter from the Royal NZ Institute of Horticultural contains a snippet on the agapanthus fertility and performance trials under way in botanic gardens in Auckland, New Plymouth, Wellington, Christchurch, and Dunedin.
The trials are looking for sterile or low-fertility agapanthus so gardeners can grow these popular plants without contributing to the ‘weediness’ of the surrounding landscapes.
Initiated by Auckland Botanic Gardens in collaboration with the nursery industry, Manaaki Whenua–Landcare Research, and others in the Agapanthus Working Group (established in 2012), the trials are looking to quantify the percentage of seed set among cultivars suspected of having low fertility.
The plants, native to South Africa, are loved by gardeners for their toughness (easy to grow at the coast, drought tolerant), abundant flowers through the hottest part of summer, evergreen, and their dense root system which can help stabilise tricky banks. Unfortunately, the common tall, blue variety seeds prolifically and so constitutes a threat to native plants in natural landscapes.
In a 2016 paper for Landcare Research, Murray Dawson notes that agapanthus were first recorded as naturalised in New Zealand in 1952. The tall blue-flower plants produce a large number of seeds – and virtually all the seed germinates.
Councils in the Wellington area, for example, are encouraging gardeners to get rid of their common agapanthus – although warn it will take a strong back, a small digger or some serious poison to do the job, while Auckland Regional Council banned the plants in 2008.
Four-year trials at Auckland Botanic Gardens and Lincoln University, which ended in 2016, showed that the dwarf-medium Agapanthus ‘Thunderstorm’ and ‘very dwarf’ A. ‘Agapetite’ were likely sterile, while the dwarf blue A. ‘Sarah’, dwarf white A. ‘Finn’, and dwarf dark blue with variegated foliage A. ‘Goldstrike’ have very low fertility.
The report concludes: “’Low-fertility’ is the most accurate term for claims made of most current cultivars.” Read the full report here (opens as a pdf).
Agapanthus ‘Thunderstorm’, bred by Kiwi Ian Duncalf, forms part of the Storm series for Anthony Tesselaar in Australia.
In her 2017 book, The Wondrous World of Weeds (New Holland), Pat Collins writes that the indigenous people of South Africa grow the plants around their homes as they’re considered a magical aid to fertility and pregnancy!
“To soothe your feet after a long hike, weave the soft leaves into a slipper shape, put over the feet and relax. Has a silky smoothness that eases your aches.”
The root is also used by the Xhosa people in a medicinal way, even though the plants are toxic to humans. Note that the sap can cause severe ulceration of the mouth.
‘Twister’, pictured above, was selected in South Africa in 2008 from the breeding programme of Quinton Bean and Andy de Wet and, after extensive trials in around the globe, the first plants were sold in 2013. Apparently, it was the first time the pair had released a plant into the international market – and they’ve had trouble keeping up with demand ever since!
In colder climates, the weedy tendency of agapanthus is dealt to over winter – or they’re grown in pots as house plants. The Royal Horticulture Society noted in 2017 that it had almost five pages of registered plants (but “the fact is that many are very very similar”.) Britain, where they’re also known as African lilies, even maintains a National Collection of Agapanthus.
Read more about plants available in New Zealand in this 2014 post.