In season

They have a reputation for being demanding divas, but it doesn’t have to be that way, says Neil Ross. He takes a closer look at the rhododendrons that thrive in New Zealand conditions.

Neil Ross looks for rhododendrons that are perfect for modern gardens.

My only real talent with rhododendrons is in killing them. During a stint as a tree warden in the UK, I spent weeks chopping them to the ground with a machete and tossing the tops onto a bonfire. In Britain you see, Rhododendron ponticum has leaped the garden fence and now runs dangerously wild in woodland and mountain fells, so my efforts were in order to save native ecosystems. Thankfully most of our Kiwi rhododendrons originate from less aggressive types; shrubs with botanical names laced with the species epithets of forrestii, hookerii, fortunei and davidii – commemorating the plant hunters who scoured the high altitude mountain passes of China, Tibet, Myanmar and Nepal in search of these stately evergreens which in their homelands form tall-trunked rainforests carpeted beneath with indigenous lilies, astilbes and primula.

Victorian gardeners were enchanted by their noble leaves, often felted on the underside in white or orange; their marbled trunks; and of course the huge trusses of speckled trumpets through spring and early summer. Rhododendron in the original Greek means tree rose, which perfectly sums up both its grandeur and splendour.

Rhododendrons love it best when they have shelter, good drainage, plenty of summer rain and cool winters. Most also demand some dappled shade.

The popularity of rhododendrons has fluctuated over the years; with shrinking gardens, gone is the demand for the mighty arboreal giants favoured by the Victorians.

Compact, beautiful Japanese Rhododendron yakushimanum has reinvented the genus. Used for breeding, this mountainous species confers a lovely compact habit with more sun and wind tolerance than most, making container-growing a viable option for courtyard gardens.

My failure to grapple with these reliable evergreens, however, has been all down to soil – few of the gardens I’ve worked in have had the acid

My failure to grapple with rhododendrons has been all down to soil – few of the gardens I’ve worked in have had the acid conditions these evergreens demand.

conditions most rhododendrons demand, and even near Auckland when we enjoyed some acidity, the humidity and dry summers meant – with their shallow roots – these shrubs survived rather than flourished.

Every spring we wrapped the trunks of our favourite specimens with neem-soaked sleeves which deliver a systemic shot of natural pesticide to the plant to ward off thrips. These sleeves are just one of the clever inventions developed by rhododendron expert Eric Wilson who established Cross Hills Gardens & Nursery near Kimbolton in the Manawatu.

Having purchased 240 hectares of beef and cattle farm in 1938, Eric saw how much the rhododendrons loved his good soil and plentiful rain, and spotted an opportunity. In 1970, the nursery was born. Today, everything is run by his son Rodney and grandson Scott with his wife Angela, who have chosen this selection of rhododendrons as some of the best that they offer.

Scott and Angela are just back from a trip to Singapore to check up on some of their finest rhododendrons which had been shipped over earlier in the year to be stars of the show at a rhododendron installation at Gardens by the Bay – an enormous nature park made out of 180ha of reclaimed coastal land. “A 40-foot container was sent out last year as a trial,” explains Scott, “and this year we packed up 450 specimens, many of them over eight feet high, to go in their giant biome which is kept artificially cold.” Of particular note – and pride

– are the 80 rhododendron standards, a method of grafting the bushes onto a trunk that was invented by Scott’s granddad at the nursery and a technique that is still swathed in secrecy.

Though farming these days is lucrative, the rhododendrons still bring in a welcome return though Scott cringes at how poorly gardeners sometimes treat their plants once they get them home. “Scott can’t bear to see these makeover garden shows when plants are poked into tiny holes,” Angela says with a laugh. “They need holes twice as wide as the rootball at least.”

The most important process at planting I’m assured, is to tease out the outer roots of the rootball to stimulate fresh root growth so the plants get established quickly.

Slicing the sides of the roots with a spade would also do the job but, “My Dad, a great inventor like his dad,” Scott recalls, “was always one to spot a retail opportunity! He had us drilling wood and banging in nails each summer making ‘root teasers’ to sell in the shop.”

And it looks like the entrepreneurial bug is catching.

Of Scott and Angela’s young sons, “one is mad about the farm and the other was busy sowing acorns in autumn – he’s planning on selling them at the Country Fair (on November 16).” ✤