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Flowers from The Cape

Mike Nelhams (Curator of Tresco Abbey Gardens)

Protea Family

The Protea family in South Africa is represented by 14 genera which are all exclusive to Africa and not found growing wild elsewhere in the world: Protea, Leucadendron, Leucospermum, Serruria, Spatalla, Diastella, Faurea, Brabejum, Aulax, Paranomus, Vexatorella, Mimetes and Sorocephalus. Most species in the Protea family (Proteaceae) are concentrated in the south-west Cape where they help to cover the mountainsides with attractive, evergreen vegetation. The heartland of South African Proteaceae lies in the Cape Floral Kingdom, a large part of which is taken up by a varied group of habitats which are collectively known as the fynbos. But for all of its magnificent floral wealth the fynbos is a very hostile environment indeed for plants.

It is usually the exotic and varied appearance of protea flower heads that grab the attention of gardeners seeking to cultivate these dramatic plants. In fact their name comes from the Greek god Proteus who could take on many different forms. The blooms of Proteaceae are actually flower heads containing a cluster of individual flowers. In some of the larger protea flowerheads, these groups may number between two and three hundred individual florets.

Cultivation of Proteaceae

Gardeners wishing to cultivate proteas must forego many habits that have been instilled over the years. Proteas ‘thrive on neglect’ and ‘can be killed with kindness’. Excessive watering must be avoided because proteas do not tolerate wet soil conditions. Good drainage, almost without exception, is one of the first rules for successful cultivation and proteas generally thrive in open, sunny positions. Because most originate from quite harsh environments where nutrient levels are low, proteas have also developed a root system that enables them to cope accordingly. As a result, except in particularly poor soils, fertilisers are to be avoided, especially those that contain phosphate which is toxic to the Proteaceae.

Watering

Proteas are remarkably drought resistant; which has led to a belief that as dry-climate plants they do not like water and should be kept dry. There is however a crucial difference between dry and well-drained; these plants will appreciate water. The more free draining the soil, the more necessary it is to irrigate. Young plants will also require more water in the first season after planting to ensure their successful establishment. More young proteas have died from being dried out than from being over-watered.

pH & nutrient requirements

Most members of the Proteaceae grow well in soils that are low in nutrients and are likely to be harmed through the application of fertiliser. Where plants are obviously struggling in poor soils or tubs, a low phosphate, slow release granular fertiliser can be used. On the whole, proteas enjoy an acid soil; it is safe to say that a pH of 3.5 - 6.5 is preferred. Some notable exceptions such as Protea obtusifolia do occur on alkaline soils in the wild, but will grow equally well in mildly acidic soil. Protea cynaroides, the King Protea, sometimes grows naturally in soils of pH 3.5 which ranks among the most acidic conditions that any plant can tolerate.

Planting positions & soil type

The healthiest plants will always be produced when grown in a sunny position. Importantly, more flower will usually be produced. Good air circulation is crucial to the well-being and long term health of plants; planting sites need to be selected to have as much air movement as possible. Raised sites or sunny slopes will aid good growth. Any garden dips or hollows will only hold water, cold air and frost; conditions potentially harmful to the plants. Proteas like plenty of fresh air and tolerate cool fresh winds. An overcrowded position can lead to poor, spindly growth and tends to provoke fungal disease. Proteas will thrive in stony, gravelly or sandy soils; loam-based soils are suitable provided they are free draining. To state the most essential factors for the cultivation of proteas: they must have WELL-DRAINED SOIL and GOOD AIR CIRCULATION.

Frost

Frost in any garden will always be a lurking killer for ‘tender plants’; some varieties will survive and some will die but choice of species, position of planting and severity of cold weather will all be factors effecting success. Some protection over the first two winters of a plant’s life is crucial. However, once wood has formed in the stem, many Protea species will not be killed outright by cold. Several proteas do grow above the snow-line in their native habitat, two examples being Protea barbigera and Protea eximia. Of course for most of the British Isles, except the most favoured areas, winter protection is essential for survival and common sense must prevail.

Propagation

There are four basic methods of propagation for Proteaceae: seed, vegetative, grafting and tissue culture, of which seed and cuttings are the most popular. Many protea seeds will retain viability for many years, however the fresher the seed the quicker it is to germinate. In the British Isles sow in spring into free-draining compost and lightly cover the seed. Some difficult species may require help by soaking in a 1% solution of hydrogen peroxide for 24 hours. Seedlings will need to be pricked out when the first sets of leaves have made an appearance.

Cuttings will produce a plant much more quickly, but be prepared to expect losses under greenhouse conditions with excessive humidity. Cuttings can be placed in a compost of 50% peat and 50% perlite and it can take anything up to three months for rooting to occur. Where possible good air circulation around plants will always be appreciated.