Protea

Protea spp.

1. Identification and origin

Proteas (Protea spp.) are shrubs or small trees belonging to the Proteaceae family, originating mainly from Southern Africa, where they form part of Mediterranean ecosystems such as the fynbos. They are widely cultivated as ornamental plants and for cut flowers, due to their showy inflorescences and long post-harvest durability. Among the species of greatest commercial interest are Protea cynaroides (L.) L. (king protea), Protea repens (L.) L., Protea neriifolia R. Br. and Protea eximia (Salisb.) Fourc.

2. Economic importance

Proteas have high value in the cut flower and landscape ornamentation market. They are appreciated for their resistance, diversity of shapes and colours, and for their ability to maintain quality during transport and storage. Production occurs mainly in regions with a Mediterranean climate, including South Africa, Australia, Israel and Mediterranean coastal areas. International demand is growing, especially in premium floriculture.

3. Botanical characterisation

Proteas have distinct morphological characteristics:

• Perennial shrubs of variable size, generally between 1 and 5 m
• Simple, coriaceous leaves, frequently glaucous
• Compound inflorescences (capitula) surrounded by coloured bracts
• Root system adapted to poor soils, frequently with proteoid roots that increase nutrient absorption
• Slow growth and high longevity under suitable conditions

The intra-genus diversity is high, with species adapted to different altitudes, soils and fire regimes.

4. Soil and climate requirements

Proteas require specific conditions for healthy development:

• Mediterranean climate, with dry summers and mild winters
• Well-drained soils, poor in nutrients, frequently sandy or sandy-loam
• Acidic to slightly acidic pH (4.5–6.5)
• High sensitivity to excess phosphorus
• Need for good air circulation to prevent fungal diseases
• Moderate irrigation, avoiding waterlogging

In colder regions, they may need protection against frost.

5. Main pests

• Scale insects (Coccidae, Diaspididae): sap sucking and sooty mould
• Aphids (Aphididae): deformations and transmission of viruses
• Thrips (Frankliniella occidentalis): damage to bracts and flowers
• Mites (Tetranychus spp.): chlorosis and foliar necrosis
• Defoliating Lepidoptera: reduction of leaf area
• Weevils and floral beetles: damage to inflorescences

6. Main diseases

• Phytophthora cinnamomi: root rot and sudden death, one of the most destructive diseases
• Botrytis cinerea: rots in flowers and bracts, especially in humid environments
• Alternaria spp.: foliar spots and necrosis
• Stem cankers (Fusarium spp., Botryosphaeria spp.): progressive decline
• Powdery mildew (Oidium spp.): white spots and reduced photosynthesis

Sensitivity to soil fungi is high, especially in poorly drained soils.

7. General cultural management

The production of proteas requires specific practices:

• Selection of species and cultivars adapted to the local climate
• Planting in well-drained soils, avoiding fertilisation rich in phosphorus
• Moderate and controlled irrigation, favouring low-pressure systems
• Formative pruning to stimulate branching and flower quality
• Removal of infected plant material to reduce disease pressure
• Strict monitoring of Phytophthora, with adequate drainage and preventive practices
• Careful harvesting to preserve the integrity of the bracts
• In cut flowers: post-harvest with adequate preservative solutions

Bibliographic references

• EPPO Global Database – Protea spp.
• CABI – Crop Protection Compendium – Protea spp.
• Vaughton, G., et al. (2010). Ecology and cultivation of Proteaceae. Horticultural Reviews.
• FAO (2020). Mediterranean Ornamental Crop Production Manual.
• Denman, S., et al. (2003). Diseases of Protea in cultivation. Acta Horticulturae.
• Lamont, B. B., et al. (2011). Proteaceae adaptations to nutrient-poor soils. In: Plant Ecology in Mediterranean Climates. Springer.