The overseas flower market pays a premium for straight, long-stemmed pincushion proteas with no insects or signs of disease but delivering such flowers is easier said than done. Depending on the cultivar, South African fynbos farmers are currently only able to export between 40% and 80% of the local harvest. Thanks to new research on growth regulators by Eugenie-Lien Louw, a doctoral student at Stellenbosch University, cultivated pincushions with short or crooked stems could become a thing of the past. Louw’s research has been hailed by some in the local fynbos industry as a game-changer.

Louw’s findings are important for the fynbos industry, as 46% of all fynbos exports from South Africa are made up of pincushion (Leucospermum) cultivars.

In addition to farms in the Western Cape (especially in the Boland, the Overberg, the West Coast and the Cederberg), pincushions are also grown in KwaZulu-Natal, around the towns of Eshowe and Hilton.

Straight-stemmed flowers

Timing is important in the application of the right combination of two growth regulators, ProGibb® and Promalin®, said Louw. In the process the pincushion plants grow more upright, rather than growing out in the bushy form.

Growth regulators are hormones that occur naturally in plants and control all aspects of their growth and development. ProGibb® is a natural version, while Promalin® is a synthetic version.

Similar products have been successfully used for years by table grape and citrus farmers. Louw’s research is the first to show that commercially grown pincushions respond well to their use.

The mixture must be applied before pincushion stems are 10cm long. This ensures that an ideal export stem length of between 60cm and 70cm is obtained as a rule, rather than as an exception. The stems present with good, continuous and uniform coverage of smaller plant leaves, and flower heads are well formed.

“There are very few crooked stems per plant if the mixture is applied correctly and in time,” explains Louw.

Industry response

Louw communicated her findings to the local fynbos industry during the recent AGM of Cape Flora SA, and at two International Protea Association (IPA) conferences in Australia and South Africa.

Some local producers, especially in KwaZulu-Natal and on the West Coast, are already following her advice. Some refer to the treatment as Eugenie’s magic mix and say that the input costs are justified by the improved margins.

“This is game-changer for our industry, and will directly benefit producers,” says Neil Hall of Philadelphia farm, outside Citrusdal.

Hans Hettasch, owner of Arnelia Farms outside Hopefield, sees the treatment as a breakthrough. “This could have a significantly positive effect on the profitability of certain Leucospermum cultivars,” says Hettasch.

Zuluflora’s technical manager Kerry Rowlands says they have had exciting results after testing the treatment. It has been used in Hilton, Eshowe and Citrusdal on cultivars that typically have problems with stem length.

“In most cases, the plants have shown an extra 30cm of growth. The plants grow in a much more upright form than we are used to,” explains Rowlands, who says the research is helping to ensure a better product for the export market.


Before Louw could test the use of growth regulators, she researched the growth and development of Leucospermum plants. “If one knows how the plant grows, one can work out how to manipulate it correctly,” she says.

Louw’s research follows on her work as technical manager of Arnelia Farms outside Hopefield. Her studies were conducted under the leadership of Dr Lynn Hoffman and Prof Gerard Jacobs of the department of horticultural science at Stellenbosch University. The work was partly funded by Arnelia Farms and the alternative crop fund of the Western Cape department of agriculture, which is administered by Cape Flora SA.

The trials, done on a semi-commercial scale since 2013, were conducted over five seasons on two farms: Arnelia Farms near Hopefield and Pomona farm at Piket-Bo-Berg. The growth regulators have been tested on two cultivars, Succession II and Soleil.

Louw tested the influence of growth regulators under different climatic conditions. She found, among other things, that it is better to mix the two growth regulators than to spray them separately. – Stellenbosch University