N.sarniensis grows at considerable altitudes in South Africa, often on north slopes, and in extremely poor soil, in areas which have autumn and winter rains and a dry summer. Flowering, from late September to early December in the northern hemisphere, precedes or accompanies the development of leaves, and is precipitated by a drop in temperature. Thus it is not possible to grow N.sarniensis hybrids in the open ground in areas where there is heavy summer rain or winter frost.

The umbels of ten to twenty flowers are carried on stems from fifteen to twenty-six inches in length, in colours which now range from orange through scarlet to crimson, magenta, lilac, purple and white and with many beautiful striped variations such as scarlet on a violet background and orange or red on white. No yellow has yet been raised. The crystalline structure of the petals results in a spectacular appearance of 'scintillation' in direct light: gold flecks in red flowers and silver in pink or white ones. There is a just perceptable fragrance in some clones in sunlight.

For cultivation under glass the necessary conditions are therefore a dry rest from the withering of the leaves in May until the flower spikes appear. Watering should then be copious until all six strap-shaped leaves have finished their growth in the New Year. Thereafter it may be moderate until the resting period begins. I prefer to repot immediately after the leaves have withered, removing any dead roots and giving the plants one thorough watering and keeping them as cool as possible until they are quite dry. This will result in a flush of new roots which will survive the resting period and be ready to begin work in the autumn.

These are plants from the mountains and they need as much light and air as they can get at all times. Research by D.S.I.R. New Zealand suggests a temperature range of 9 - 13 C (48-55F) during growth, but the plants are quite safe so long as they do not freeze. Higher temperatures during the growing season are undesirable except by day in sunlight with full ventilation. These plants are not therefore suitable for areas which have a hot autumn and winter. When at rest in late spring and summer the bulbs will stand high temperatures.

N.sarniensis hybrids are not particular as to soil but too much fertiliser encourages their only serious enemy, a dangerous latent virus. Fertiliser is safe only in expert hands. I preferred to have smaller bulbs and no virus and only saw traces of it in one or two plants amongst several thousand in the course of 25 years. They are usually grown with three-quarters of the bulb above the surface of the soil.

Some growers are using sand cultivation with great success but I have no experience of this technique. Meanwhile research by the Horticultural Research Institute of New Zealand into temperature controls and timing has resulted in moving the blooming period forward to a point two to three months ahead of the natural flowering time. In my view, however, it would be more useful to move the flowering period back into the winter months when cut flowers are scarce, rather than forward into the summer months when they are plentiful. This research does however show that flowering of these plants can be manipulated and the New Zealand specialist grower, Monte Hollows, has built up an important cut flower export trade and is breeding for commercial cutflower characteristics.

From the foregoing it will be seen that, as in the case of many orchids, it is not easy to grow these plants satisfactorily in a greenhouse regulated to suit a general collection of plants.

Peter Smithers