Christmas Trees for High Summer
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n a g e R r e t e Christmas P © trees for high summer Kevin Line propagates pohutukawa, the New Zealand Christmas tree. Fig. 1 Pohutukawa in its native New Zealand. ince autumn 2008 I have at the coast, sometimes Pohutukawa belongs to the Sbeen propagating overhanging the high-tide line. Myrtle family (Myrtaceae) . Metrosideros excelsa , also On the island of Tresco in the The tree grows up to 25m known as pohutukawa. One Scilly Isles it’s now used as a high, developing a spreading of twelve Metrosideros species, major windbreak, replacing dome shape. The red bottle- all native to New Zealand the old Monterey pines. brush flowers comprise a (fig. 1), it has an incredible Introduced to South Africa, proliferation of stamens resistance to gales and is salt less happily it’s so prolific that (fig. 2). The blooms appear in tolerant, so it’s often found it’s regarded as an invasive July and August in the UK, growing on rocks and shores weed. and from November to n January down under – hence a g e it’s commonly known as ‘the R r e t New Zealand Christmas tree’. e P © It’s also been called ‘the Settlers’ Christmas tree’ and ‘antipodean holly’. Propagating Metrosideros excelsa My experience of pohutukawa began in the summer of 2006. Shrubby potted specimens of the trees are used to adorn the terrace of the mid -1 6th-century historic house with a 6½ acre garden where I am head Fig. 2 The ‘flowers’ are stamens. gardener. It’s a labour-saving 59 e e n n i i L L n n i i v v e e K K © © Figs. 3a & b Six years from cuttings, two plants come into flower. shrub, requiring little watering height of 1.3m; each shrub taken and five cuttings throughout the summer has a varied growth habit of inserted into each of four months and yet producing an single and lateral stems. I 2-litre pots with a 2:1 mix of abundance of the flowers in thought it would be peat-free compost and grit extremely dry conditions. interesting to take cuttings sand, as I’d seen woody In the autumn of 2008, as from single and lateral stems subjects develop good rooting an experiment, I started to to see if the cuttings systems in such a mix. propagate pohutukawa. continued to produce the Ten cuttings were taken Including the height of the same pattern of growth. from the greener, softer parts pots, the shrubs stand at a Twenty cuttings were of the plant stems closer to e the shoot tips, and the other n i L ten from riper wood lower n i v e down. All were placed in the K © heated end of the glasshouse, with assisted heat to maintain 10–15º C. By the following spring just two of the cuttings had rooted, both taken from woodier sections of stems. These two plants are now just over a metre high and in spring 2014, with assisted heat in the propagation unit of the glasshouse, both had a profusion of early flowers Fig. 4 In a cool greenhouse, roots develop well. (figs 3a & b). 60 e n I made a second attempt in pattern of each plant has i L n November 2011: a larger followed that of the parent i v e proportion of the cuttings plant: a single-stemmed K © were taken from woody stem cutting has produced a single- material, and all the cuttings stemmed plant, while were put in the cool section of lateral-stemmed cuttings have the glasshouse to encourage not produced a single, root formation. I’d found this dominant stem (figs 5a & b). method more successful when To date only one of the propagating Arbutus and new plants has died, and the e n i L Catalpa trees. rest have remained strong, n i v By mid-March 2012, all the vigorous and healthy. The e K cuttings had started to root – a tallest single-stemmed plant is © gentle tug confirmed there currently 80cm high. The was resistance in the pots. capillary matting appears to Removing some of the have stimulated root cuttings from the pots with development – the roots of the compost intact exposed a some plants have crept several fine network of roots (fig. 4). centimetres through the side As the plants developed drainage holes on to the through summer 2012 it was matting. These plants will be evident that the stronger root potted on into 3–4 litre pots. systems were formed by In midsummer 2014, the woody-stem cuttings. The young plants were placed young plants were potted into outside to be watered Figs. 5a & b Single-stem and 1L pots, and thrived although overhead from a hose branch-stem cuttings develop like their parent plants. watering was reduced to that sprinkler to encourage new given to the parent plants. tip-growth on the branches. hot days – very different from The young plants were M. excelsa . placed on capillary matting to Metrosideros umbellata The combination of see if water uptake from the We also have a small potted warmth and moisture brought base would be sufficient for shrub, just under a metre tall, the shrub into bloom. It was sustained root formation and of another Metrosideros well worth the wait to see the shoot development. By species, umbellata , a flowering small, bright crimson bottle- summer 2013, this method plant from the cooler south of brush flowers through July had proven successful with a New Zealand. I’d not been and August. With coppery mixed formation of single- able to induce it to flower young leaves, it is one of the and multi-stemmed lateral until 2013, when my fortunes hardiest Metrosideros species, growth. The plants were then changed with a concerted and it thrives outside in potted on to 2L pots in peat- effort to keep it well Cornwall. free compost. The growth watered during exceptionally I can recommend both. Kevin Line is a head gardener/plantsman in the north Cotswolds. Kevin writes a blog on plant propagation – Digging deeper – in Horticulture Week online magazine, (Parks and Gardens). www.horticultureweek.co.uk. 61.