Gardening: Summer's ablaze with pohutukawa

It's a blooming good season for pohutukawa in Whanganui. Photo / Bevan Conley

Each season, each year is a bit different to the one that went before it and such variables are highly noticeable in big trees.

This year the flowering of pohutukawa trees around the region has hit the jackpot. The intensity of blooming on the pohutukawa trees is outstanding.

My observation through Whanganui is that they are offering noticeably more flower power this year than in the past few.

A tree flowering is for seed production and survival while we gain aesthetic enjoyment along the way.

Ecologically there will likely be reasons and cause and effect of such a great floral display this year. Meanwhile, let's enjoy the beauty - I highly recommend to go to some of the vantage points around Whanganui and see how many of these iconic New Zealand native trees you can spot.

There are actually a number of varieties of metrosideros species that are grouped together under the widely recognised common name of pohutukawa. Not all are giant forest trees and a number can be grown in the small home garden.

Pohutukawa have become very popular among many home gardeners.

When New Zealand was settled by Europeans, pohutukawa were found growing naturally close to the coastal areas of the North Island.

From the Three Kings Islands southwards to Poverty Bay on the East Coast and around the mouth of the Urenui River, just north of Waitara on the west coast.

They also grew along the shores of some of the lakes in the Rotorua district. Since then many species have been extensively planted in many parts of New Zealand, both inland and on the coast. They have been used as street trees in a number of cities, including Whanganui, and many have been planted in parks and gardens.

The largest pohutukawa in New Zealand, Te Wahoa Rerekohu at Te Araroa, is said to be more than 300 years old and has a height of nearly 21m and a spread of almost 40m.

We can also see good specimens in and around Nelson, on Banks Peninsula and as far south as Dunedin on the east coast and Jackson's Bay on the west coast of the South Island. It is well known that the pohutukawa grows best by the sea.

The familiar species, Metrosideros excelsa, is commonly referred to as the New Zealand Christmas tree. The Maori name pohutukawa, "drenched with spray", refers to the way these robust trees cling to rocky cliffs and endure wild ocean storms.

It can grow into a fairly massive spreading tree that overhangs the water, the huge branches growing out almost horizontally, and forms deep roots that enable the tree to cling to steep banks and rocks and remain there.

Pohutukawa trees often have aerial roots growing from low branches or the trunk. They can form a tangled mat or net and may join around the trunk or branch from which they arise. Only the larger roots may reach the ground.

Some good specimens are along the GF Moore Drive entranceway to Springvale Park in Wanganui. Photo / Bevan Conley

The oldest and finest pohutukawa trees can be seen around the Coromandel peninsula and also near Opotiki and Ohope Beach in the Bay of Plenty and the East Cape coast road.

The key feature is the vivid summer display during December and January when the tree is often completely smothered with its orange scarlet to deep crimson flowers.

These comprise dense clustered stamens which open from powdery buds, totally covering the tree.

Fallen stamens can lay a red carpet on the ground. Many birds are attracted to pohutukawa flowers because of the copious nectar in the flowers.

These trees are perfect in many landscaping situations and are obviously a good first choice as a frontline seaside plant against prevailing strong salt-laden winds.

In Whanganui they can be planted in most sandy to heavy clay free-draining soil that has been deeply worked and enriched with organic compost in a full or partial sun position.

Mulch 50mm to 75mm and water during dry periods while the trees are becoming established.

Once established, the trees are very drought-resistant. Pohutukawa normally branch from the ground but a single trunk can be formed with careful pruning and staking.

As a hedge or screen, regular trimming encourages and maintains the desired size to form an almost impenetrable barrier. Most species are fairly hardy but juvenile growth needs protection until well established with adult foliage.

Pohutukawa also make good tub or container specimens for courtyard, patio or deck situations.

They also do well for several years before requiring repotting or planting out. Most pohutukawa varieties respond very well to being trimmed and can be kept significantly smaller than their growth potential by an annual prune.

The most commonly planted larger growing variety is Metrosideros excelsa or selection of it called "Maori Princess". It is what we would all recognise as the iconic traditional pohutukawa with spectacular, deep crimson red flowers from December onwards into summer.

Metrosideros Springfire is an early flowering variety which has more orange-red coloured flowers from spring to early summer. It grows about 4m high by 3m wide.

Metrosideros Kawa Copper is a variety released about 10 years ago. It is a cross with the northern rata. As well as deep red flowers, it boasts attractive coppery coloured new foliage. It grows about 2.5m high by 2m wide.

Metrosideros Kermadecensis Variegata is a fine compact variegated form, extremely hardy to coastal conditions and an ideal tub plant. The foliage is broadly margined creamy yellow and provides a garden with distinct colour. Some good specimens are along the GF Moore Drive entranceway to Springvale Park in Whanganui. These began as 150mm high plants in the gardens in front of the Memorial Hall forecourt and, when they were too large for the gardens, were successfully transplanted to their current site in the 1970s by parks personnel of the day.

Metrosideros Tahitian Fireball is a good smaller form of pohutukawa that will fit into a courtyard garden or pot. It forms a beautiful shrub that grows about 1.2m high by 1m wide. It produces brilliant red flowers two or three times a year, mostly during the summer months.

Have a great week – slip, slop, slap, wear your sunhat and enjoy the weather and your garden.

• Gareth Carter is general manager of Springvale Garden Centre