Turning the air blue

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.

White agapanthus flower – the tall-flowered plants come in blue or white. Image: Wikimedia

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.

Agapanthus ‘Thunderstorm’ has variegated foliage and grows to about 30cm. Image: Ian Duncalf

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.

Agapanthus ‘Navy Blue’ growing in Alnwick Castle gardens in Northumberland. This is a deciduous plant. Photo: Sandra Simpson

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.

The striking flowers of Agapanthus ‘Twister’ – white, pink and blue – seen last year at Wollerton Old Hall in Shropshire, England. Another deciduous agapanthus. Photo: Sandra Simpson

‘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.

Coming up from Tesselaar

One fine day and the world’s gone to the garden centre! If one of the big box stores was anything to go by yesterday – carpark packed, people loading up potting mix, plants, pots, stakes, etc – we’ve all been busting to get into the garden.

The Vege Grower and I were surprised to be stopped by a woman who opened with “you two look like serious gardeners” and followed up with a really surprising question – how do I get rid of the barley that’s come up in what was my strawberry patch? She reckons the (well-known brand) barley straw she used as mulch has seeded all through her raised bed! She seemed intent on ‘dabbing’ on a poison so our advice to hand pull it or dig it over probably fell on deaf ears.

We weren’t immune to the bursting out of spring either, coming away with a glazed pot (been promising to repot a wisteria for a year!), a white Cosmos (99c and just the thing to set off some terracotta marigolds I got from another big box store this past week), a supposedly-dwarf Grevillea, Ignite, and another Osteospermum Blue-eyed Beauty to join last year’s plant which has got a bit leggy. And I finally got the zinnia seeds out, bit late I know, but better than never.

At the Tesselaar-hosted lunch in Auckland at the beginning of the month, we were not only treated to delicious food and the Flower Carpet Pink story to celebrate its 25th anniversary, we also got to hear about some new plants that are coming through the trial system, including one from Auckland plantsman and head of the Auckland Botanic Gardens, Jack Hobbs.

He’s crossed a pohutukawa (Metrosideros excelsa) with the dwarf M. ‘Tahiti’ to create something with felted new growth, a bright flower with deep-red stamens that will bloom at a different time to our native trees. Jack says it looks like it’s going to be sterile.

Volcano Phlox. Photo: Anthony Tesselaar International

As well as two new Flower Carpet roses (which we were sworn to secrecy over), Anthony Tesselaar was also singing the praises of Volcano Phlox, developed from an old species found in Siberia, one of the only phlox species not from North America. The plants are proving to be disease free (no powdery mildew), tolerant of a wide temperature range (they’re being trialled in the northern US, as well as Australia) and are scented. The first plants in the range are already available in the US with more coming through.

Tuxedo is a line of dark-foliage hydrangeas – the images I’ve seen show a deep purple-bronze leaf – that grow 1m x 1m. “We want to create excitement to get people into gardening,” Anthony said. “This has a very distinct colour and will be a sensation.” Tuxedo hydrangeas are about 3 years away for New Zealand.

Something else that’s about 3 years away here – but will undoubtedly be a sensation when it lands – is a rose with the working title All in One. From Noacken Roses in Germany, which produced Flower Carpet, All in One is a compact bush that is disease resistant, has glossy foliage and covers itself in scented flowers.

The combination of disease resistance and perfumed flowers is a major breakthrough in rose breeding as genetically one has generally precluded the other.

Anthony saw field trials of the rose 5 weeks ago in Germany and was delighted. “The buds open like a Hybrid Tea rose, become more full and by the time they’re in full bloom look like a David Austin flower – and you see them concurrently all over the bush.”

He says the bushes are “a bit bigger” than a patio rose and that the flowers easily last 10 days in a vase.

“We’ve always said Flower Carpet are roses without the work, this new rose will be a garden rose without the work.”

Sweet Spot ‘Calypso’. Photo: Anthony Tesselaar International

Finally – and available now – is the Sweet Spot rose, part of The Decorator Rose stable. Single flowers with a colourful ‘eye’, the roses have been developed from work started by the renowned English rose-breeder Jack Harkness and completed by Dutch rose-breeder G Pieter Ilsink of Interplant Nurseries. Here’s a 2014 post I wrote about Helthemia persica, one of the parents used in the breeding of such roses.

I notice that the accompanying information suggests the roses will need to be sprayed to perform at their best.

“Young people aren’t buying plants, they’re buying decoration,” Anthony said. “They could just as easily buy a cushion so we have to give them a good reason to buy a plant.”

He has a theory that women become gardeners a year after the birth of their first child – and, as couples have delayed having their first child, this has meant a loss of some 10 years to the gardening industry (ie, women start gardening at 32 not 22).