Fruit and food technology research institute, stellenbosch

FRUIT AND FOOD TECHNOLOGY RESEARCH INSTITUTE, STELLENBOSCH
INDIGENOUS FLOWERS – CIRCULAR No. 2 – OCTOBER, 1965 WHERE CAN PROTEAS BE CULTIVATED?
Most South African Proteaceae show a remarkable adaptability with regard to climatic conditions and can be cultivated in both summer and winter rainfall areas. Yet their growth is influenced by various factors which must be taken into consideration when the plants are cultivated either on a large or a small scale. Among these factors are the following: TEMPERATURE AND WIND The winter rainfall region has a hot, dry windy summer. It is the natural home of most of the proteas. However, when high temperatures accompanied by much humidity occur without wind, a sultry condition detrimental to the well-being of the proteas is created. Under these circumstances the plants should be placed with care so that most use can be made of any possible draught or movement of air. Proteas are far more resistant to dry heat or even dry cold than to humid heat. Wind is thus advantageous, yet small plants should be protected against strong winds which may expose the delicate roots. Proteas flourish in the sun, although some shade, especially in the afternoon may be beneficial. This is, however, only a general statement since different species differ in their preference for full sun or for partial shade. A few species eg. Serruria florida will do surprisingly well in the shady part of the garden. Protea cynaroides is amongst those which will grow in almost complete shade but this situation is not recommended, as the plants become too lanky for beauty. Protea macrophylla (lorifolia) on the other hand flourishes even in scorching sun. Most species are frost resistant, provided the period of heavy frost is not too long. It is, however, advisable to protect young plants against frost until wood begins to form, usually in the second year. Icy winds during a period of frost may shrivel the leaves and damage young flower-heads. A windbreak of trees (eg. Keurboom – Virgilia oroboides) is recommended or, in a small garden, a fence of palings. SOIL Nearly all proteas thrive only in well-drained acid soil with a pH of 4.5 to 6. There are, however, a few spectacular species, such as Protea obtusifolia and Leucospermum muirii, which grow in alkaline soil. Mimetes hirta and Leucadendron glabrum are among the very few species which can grow in boggy places. Slightly clayey soil is less harmful to Protea neriifolia, Protea susannae and even to Silver trees than to most other species. Heavy clay is quite unsuitable for the growing of proteas. Fertilizers and manures are only recommended to meet the requirements of particular soils. Advice in this regard for any specific area will be given on application. WATER Proteas need a great deal of water, but the water must drain away slowly. In summer-rainfall areas proteas should be watered during winter, especially in the late winter. In winter rainfall areas it is often not necessary to water the plants during the dry summer after their second year – but if water can be supplied they undoubtedly benefit from it and will grow faster and flower sooner. Since proteas are extremely sensitive to a high concentration of salts (even nutrient salts) in the soil water, obviously brackish water is detrimental. It is the importance of water which influences the selection of the situation or aspect, especially for large scale plantings. A southern slope or aspect usually has more cool moisture since it is not so exposed to the hot sun and its more direct rays. Mountain slopes along the coast often get a cool mist 108
from the sea and this would then be the deciding factor for suitability even if the aspect is west or north.
Those species with a long dormant period during summer do much better on a dry slope than for
instance Protea cynaroides with more than one growing period in the year. All proteas need a great
deal of water during their growing periods.

Source: http://www.ppsa.co.za/wp-content/uploads/2013/06/108-Where-can-proteas-be-cultivated-Vogts-M-1965.pdf