Posted on 14.11.2017 |
Updated on 26.11.2017 |
Added in Plant of the Month
Neoshirakia japonica
 In the arboretum nursery at Kew Gardens |
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Ever since I first saw the fascinating Neoshirakia japonica growing at Kew Gardens many years ago, it has been one of my favourites for autumn colour. I got to know this plant under the name Sapium japonica, but recently due to taxonomic research it has been put into the genus Neoshirakia (Euphorbiaceae) which does sound much more mysterious.
 Two year old tree grown from seed |
 Four year old specimen grown |
When one thinks of the family Euphorbiaceae, it is usually the yellow and orange spurges commonly seen in herbaceous borders that first spring to mind, followed closely by the succulent forms from the arid regions, and thirdly the Poinsettia (Euphorbia pulcherrima) that will shortly be appearing in many Christmas displays.
Neoshirakia japonica is a hardy shrub/small tree native to Korea, China and Japan where it grows in moist forests at an altitude of 100-400m. In the wild they can reach a height of 25ft, but in cultivation they don’t often get this big. Leaves are alternate along the stem, smooth edged and elliptical shaped. Starting nettle green in colour, leaves grow to a size of approx. 7-16cm long, 4-8cm wide and mature to dark green. Flowers are inconspicuous and appear on thin catkins around mid-summer. In the autumn, plants growing in full sun will gradually turn from green to blood red with countless vibrant shades in between. Those in semi-shade finish yellow before falling.
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Despite being an easy to grow species, it is rarely seen in British gardens, only usually in botanic settings and arboretums. This species is one that is only available from a handful of specialist nurseries, but well worth the effort of finding it.
If attempting to grow from seed, sow fresh seeds during autumn in pots containing a free draining seed mix, the seeds should only be planted just below the surface. Next cover with a thin layer of fine grit and place the pot in a cold frame or unheated green house and keep moist. During the autumn/winter the low temperatures will stratify the seeds, this will help with germination when temperatures increase in spring.
It can be grown from cuttings, but they can prove tricky unless you have a mist or fog facility which allows you to create the perfect microclimate. I have successfully rooted them on several occasions using a closed tent with 20°C basal heat in a peat, sand & bark mix. Semi-ripe tip cuttings taken in early summer 6-8 inches long, dipped in a 0.5% IBA work best.
As a slowish growing, smallish tree, this makes a good specimen, packing a good punch for its size with large colourful leaves that seem to last a good while on the tree. Perhaps its scarcity is a reflection on it being trickier than many others to propagate, but if you can find one, it is certainly worth having.
