General guidelines to growing and maintaining healthy Proteaceae
What an amazing morning we had last Friday wondering in the Protea fields, admiring and learning all about these noble plants. Gerry Botha, owner of Petals Fynbos Nursery gave an excellent lecture on seed harvesting, propagation, soil requirements, & pruning. We also learned that smoke is needed for the seeds to germinate. Gerry grows proteas for the export market, he also sells some blooms and plants at the Sedgefield Market.
Our local nurseries all stock Protea species from Arnelia Protea Nursery. Arnelia Farms was started by Hans Hettasch in 1999 with the purchase of a piece of land near Hopefield on the West Coast of the Western Cape of South Africa. Hopefield is 35km inland from the coastal resort town of Langebaan, half way between Malmesbury and Vredenburg.
Arnelia Farms has 15ha of established cutflower plantations, mainly of Proteaceae in the genera Protea, Leucadendron and Leucospermum as well as Chamelaucium (Geraldton waxflower).
The wholesale nursery at Arnelia started off producing plants for our own plantings as well as to supply other commercial cutflower growers with plant material. Demand for quality Proteaceae plants for gardens led us to start growing plants on, mainly in 16cm plastic pots, for the Garden Retail Trade and for Landscapers.
The management very kindly consented to have their article copied to our site.
Proteaceae species in their natural habitats withstand a wide range of temperatures. In summer, temperatures can reach well over 30°C and in some mountain areas, winter temperatures fall to below zero. Tolerance levels differ between species, but the Proteaceae family can tolerate large variations in temperature.
Generally, populations of the same species grow in close proximity to each other. This establishes a dense vegetation cover for minimal root disturbance; keeps the soil cool and helps to reduce the rate of soil-water evaporation. Soil conditions for Proteaceae species vary from species to species, but they are most commonly found in very nutrient-poor soils. A soil with more than 30% clay in the top- and sub-soil is not recommended for the planting of Proteaceae species because of likely drainage problems and a high incidence of fungal disease. A well-drained soil is probably the most important requirement for Proteaceae species under cultivation. Most fynbos, including the Proteaceae family, thrive in acidic soils; although some species can tolerant more alkaline soils.
At planting, mulching should be considered as it helps to reduce weed growth. This is an important point to remember as Proteaceae species do not like to have their root systems disturbed. Mulching also insulates the soil, keeping it cool in summer and warm in winter. It keeps moisture in the soil, helping to reduce irrigation. Mulching additionally conditions the soil as it decomposes by adding small amounts of nutrients and organic matter. This layer of mulch should be laid at planting, 5-8cm thick, but kept away from the stem to minimise the risk of fungal diseases. Types of mulch, which can be used include: wood chips, pine bark (well-aged), gravel or crushed rock, black plastic sheeting, newspaper or woven reed mats.
Young Proteaceae plants should be tip pruned after the first six months to a year after planting, generally in spring to late summer. This encourages a bushier, more compact growth habit. The plants can be pruned again after the first flowers by cutting the flower stem 10cm above where the stem branches out from the main stem. It is also preferable to cut out any weak stems that have failed to flower, thereby encouraging the remaining stems to produce healthier, more vigorous growth. The same can be said for damaged and crooked stems in both young and established bushes. Pruning of Proteaceae species improves the quality and quantity of flowers, helps to reduce disease, extends the life of the plant and creates bushier, more compact plants.
General pruning tips for each Genus:
Protea species– Non-flowering stems of the genus Protea should not be pruned back to bearers as these will produce flowers the following year. The variety ‘Pink Ice’ will only flower 18 months later if pruned in June/July. Care should be taken when pruning back older Protea plants; never remove more than 50% of the plant leaf area and leave about 15cm of healthy leafy stem on which new shoots can be borne.
Leucospermum and Leucadendron species – Will flower every year and the flowers should be cut back to bearers after flowering. The bearers, with healthy leaves, should be cut approximately 10cm from the main stem. Non-flowering stems can also be cut to the same height, but thinner excess stems should be removed, as should poorly shaped stems and suckers.
Each bearer should produce two to three flowering stems for the next season. These flowering stems will increase in number as the plant becomes older and larger. As the stem number increases, the length of each stem will decrease and so the removal of a few of the extra shoots will help to increase stem length. The removal of these shoots is best done early in the growing season, while the shoots are still soft and easy to remove.
In order to keep a natural look within the landscape, only cut half the stems back to bearers after flowering (go through the bush and cut every second stem). The remaining stems can be cut back to bearers as soon as new shoots start to appear (on the previously pruned bearers).
Proteaceae species grow naturally in very nutrient-poor soils and so there is very little need for additional fertilizer application. All members of the Proteaceae family have a very narrow range of optimal concentrations of mineral elements and are extremely sensitive to excess phosphorus and nitrogen. For these reasons, particularly fertilizers high in phosphates should not be used. The addition of compost to the soil should also be avoided as the compost may have high levels of nitrogen and phosphorus, which are potentially toxic for Proteaceae. We recommend that the plant material removed during pruning be left on the ground to decompose and help to replenish soil nutrients.
Additionally we recommend products such as:
Wonder Ferrofood granules (Efekto) or any other iron chelate product if the plants start to show signs of yellowing (apply once to rectify according to lowest recommended application rate)
Choose only one of the following products:
Seagro fish emulsion can be added according to lowest recommended application rate, twice a year. Once after pruning in summer and once in late autumn
Wonder Vitaliser Rose and Flower 8.1.5. (Efekto) applied at lowest recommended application rate once a year after pruning
Bounceback can be applied twice to three times a year at 50g per plant, spread on the surface around the plant. Application after pruning, in late autumn and in late winter/spring.
Ed’s Garden Health Rose Vitaliser 11.1.8, applied at lowest recommended application rate once a year after pruning.