Pittosporum for winter colour
Now the leaves are down and the garden looks bare, there is a role for some evergreen trees in providing greenery and to lend an element of solidity. Pittosporum is a fine, small tree for this purpose, although there is a risk that it might succumb to hard frost, as it did in the winter of 2010.
In that winter, pittosporum trees that had survived with minor damage for 30 years were killed outright. The popularity of pittosporum then plummeted and still question marks are raised about planting this fine tree. But for those possessed of the temptation to grow plants that are close to the limit of their ability to survive, the risk is part of the challenge.
Even in 2010, not all pittosporums were killed. The east coast did not experience the lowest temperature levels and many specimens survived with surface damage to foliage and twigs. Away from the coastal areas, damage was more severe.
The most widely grown and hardiest species, Pittosporum tenuifolium, is native to New Zealand and has the Maori name of 'kohuhu'. It has dark-coloured bark on the stems and glossy, green, wavy-edged, oval leaves about five centimetres long. The basic green kind is the toughest and best survivor.
It has given rise to selections with purple, gold and silver-white leaves. These are not as hardy but they are very decorative, many of them smaller than the original which can reach about eight metres tall and is too big for small gardens. The smaller kinds are often trimmed to shape and to keep them neat.
The most widely grown purple variety is 'Tom Thumb', which makes a small bush or tree to two metres or so. Its leaves emerge green and darken in the sunlight during summer, turning to a rich dark purple-red. Older purple forms, 'Purpureum' and 'Nigricans' have green leaves that turn purple-bronze.
'Silver Queen' has grey-green leaves with a white margin and gives an overall effect of lightness. It is relatively small. 'Irene Paterson' is a smaller tree or bush, slow-growing, the new leaves creamy white. 'Garnettii' is a bigger bush or small tree to five metres, with greyish green leaves margined with creamy white, and wine-coloured spotting in winter.
Of the golden forms, 'Warnham Gold' is the best, but there are others, such as 'Abbotsbury Gold' which has gold leaves with green margins, the variegation fading. 'Golden King' is upright, tall and has green-gold leaves.
Pittosporum can be planted in any good soil that is not heavy or wet, and in sunshine. It is pretty tolerant of wind but suffers some damage in severe exposure.