Study tour of South African bulbs
By Helen Brent
In September 1999 I arrived at Cape Town, South Africa, to begin a 12 day study tour relating to the study of South African (S.A.) bulbs. There are so few of them within the S.A. bulb collection held at Kew, that they fail to represent fully the diversity in this group. Many are either of unknown origin or have been in the collection for many years and are declining in vigour. Therefore the purpose of my visit was:
- to study S.A. bulbs in their natural habitat and so aid my understanding of how they should be grown in cultivation;
- to gather information regarding the aspects involved in propagation and maintenance of S.A. bulbs, which will be beneficial in aiding successful cultivation of S.A. bulbs and help improve my own propagation skills;
- to increase the S.A. bulb collection held at Kew by the purchase of selective material cultivated from stocks of known wild origin.
My trip enabled me to study the S.A. bulbs in their natural habitat. Invaluable information was gained by seeing the exact growing conditions in the wild of a particular species.To be able to determine whether a drier or wetter compost might be needed, a more acid or alkaline soil, or just simply more winter sunshine, I am sure will help in producing a full pot of flowering bulbs for the future display in the Alpine House.
Through my experience of viewing different species in the wild I was able to help determine the potting mix to use at Kew. I observed different species regularly growing in soil of a specific texture and noted how this could influence the potting mix, albeit that the primary factor must be suitability for pot culture.
Within the period of a week I had two soil samples to examine. From high in the mountains of the Piketberg the sample was a soft grey sand with practically no loose vegetable matter in it. My second sample from high in the Amatola Mountains, the soil was scratched out of a crack in the rock. By volume it was 5% soft black dust and 95% pieces of dead, dry black vegetable matter. By weight the proportions were exactly reversed. The pH readings were respectively, 3·9 and 4·0. Therefore, I was able to determine that soils of essentially different texture had virtually the same acidity and so plants found in these areas could be potted into the same mixture with a high softish sand proportion. This and other invaluable information will hopefully contribute to a better cultivation regime for the S.A. bulb collection at Kew.
I was fortunate to have the opportunity to study a wide variety of habitats. From Cape Town I travelled approximately 200 miles north along the West Coast to Nieuwoudtville, then approximately 90 miles east to Caledon and, finally, an internal flight to Port Elizabeth to the Eastern Cape region, some 500 miles east of Cape Town.
Among the memorable places I visited was Waylands Nature Reserve, a small private reserve. This is one of several small reserves in the Darling area along the West Coast. The vegetation is largely transitional between West Coast Renosterveld and Sand Plain Fynbos. The seasonally waterlogged soils support a diverse array of geophytes and annuals. At the time of my visit hundreds of species were flowering altogether in their thousands, in a riot of colour and harmony. This lasts only briefly, passing within a few weeks, but while it lasts it is breathtaking. Thousands upon thousands of flowers: Babiana, Onixotis, Wachendorfia, Romulea, Spiloxene, Lachenalia, Watsonia, Hesperantha, Geisshoriza, Galaxia, Moraea, Gladiolus; all flowering at once covering the ground in an uninterrupted carpet of colour far beyond the skill of any human gardener.
In contrast to Waylands, further north along the West Coast I visited the Glenlyon Estate in Nieuwoudtville. Glenlyon is famous for its unique flora, emphasised by the fact that the area supports a rich concentration of geophytes. The families Iridaceae, Liliaceae and Asteraceae are particularly well represented. The property is 6,500 ha. in size. At Glenlyon they have integrated the natural flora into the farming system in such a way for it to become an asset. In very sensitive areas, where farming practices might endanger survival, the area in question is fenced off until they understand the management well enough to allow fence removal. Management of the natural flora is achieved by simulating the role played by the vast game herds of yesteryear; the major difference is the fact that they are limited in having to perform the simulation with sheep. Animals prune plants, remove dry residue and are nature’s way of compressing seeds into the soil. It was interesting to note that those species growing undisturbed by the sheep on small fertile hillocks did not appear to thrive as much as those integrated as part of the farming regime. Perhaps sometimes we are too kind to the plants in our care.
In order to study the cultivation of S.A. bulbs I was able to visit Kirstenbosch National Botanical Garden and speak with Graham Duncan, a well-known authority on the subject of S.A. bulbs. Additionally I visited Capeflora Nursery and the Croft Nursery in the eastern Cape, being specialist bulb nurseries who have developed the expertise necessary for successful cultivation of S.A. bulbs. Visiting these nurseries and seeing the techniques and protocol employed in propagation and cultivation provided valuable knowledge, enabling me to build upon my existing propagation skills.
Much of the seed collected by Graham Duncan and the other nurseries I visited, originated from quite high altitudes. Additionally the areas in question are on more or less the same latitude to many of our northern hemisphere bulbs, for instance: Cyprus, Crete and Morocco. Therefore, logically I should be able to grow many S.A. bulbs under the same conditions, either planted outdoors or in cold frames. As our stocks of S.A. bulbs build up, I intend to check their hardiness in the British climate and am hopeful that some will succeed and can join Nerine bowdenii, Hesperantha coccinea, Zantedeschia aethiopica as established garden plants. The opportunity to meet with and discuss these methodologies with experts in the field of S.A. bulbs afforded me with the opportunity to gain first hand knowledge of management techniques.
Since the cultivation of bulbs is my specialist area of work at Kew, I found this trip to be immensely absorbing and of great benefit to aid my understanding of S.A. bulbs in cultivation. This trip was enormously profitable in as much as my own personal knowledge of S.A. bulbs was augmented. In addition it has made me realise how much more there is to be learnt. Finally I wish to express my gratitude to the following organisations for the support shown towards my study tour: Kew Guild, Bentham-Moxon Trust, International Plant Propagators Society and Royal Horticultural Society.