Here we look at a special plant in a bit more detail to be appreciated by enthusiast and beginner alike.

Banksia. (Proteaceae) 

Many gardeners may be familiar with some of the curious plants that have arrived in the UK over the last two centuries from Australia and whilst being slightly tender some have survived the British weather where protected.  One that comes to mind is the unusual red flowers of the ‘bottlebrush tree’ Callistemon, which is now regularly available in garden centres.   

Whilst not yet generally seen in UK gardens another wonderful group of evergreen shrubs and trees is Banksia, which was named after Sir Joseph Banks the British botanist who first collected these plants. In their native land all types of banksias are popular in cultivation, not only for their unique flower spike arrangement, but for their unusual growth habits and attractive foliage. The delightful flowers are rich in nectar and are attractive to honey-eating birds and can be used to make long-lasting indoor decorations when dried.

Banksia, the Australian Honeysuckle, has leathery leaves and through spring and summer has long-styled flowers in dense terminal spikes which resemble brilliantly coloured, whiskery cones.  The seeds ripen in flattened, woody capsules which resemble duck bills amid the bristly remnants of the flower cone and are very diverse and decorative. 

Whilst not often seen in UK gardens Banksia was first introduced in the late eighteenth century and is a spectacular and distinctive genus that contains some 50 species ranging from prostrate shrubs to small trees.  In the UK they will thrive in sheltered locations and will tolerate short-lived frosts to -7°C/19°F if the air is quite dry.  Beware though most banksias are frost tender in the wetter UK conditions where they need excellent drainage and require full light.  General fertilisers should not be applied as banksias are intolerant of phosphorus which could then result in iron or nitrogen deficiency. If these conditions do occur they can be corrected with applications of iron chelates or ammonium sulphate respectively.  In general cultivation you should remove dead flowers, and tip prune constantly to promote bushiness. 

In less favoured locations Banksias can be grown with the protection of a greenhouse or conservatory and will require a minimum temperature of 7°C/45°F.  Use a compost made from sharply drained, sandy soil that contains little phosphates or nitrates maintaining daytime temperatures during September to March at 15-17°C (60-65°F) and March to September at 13-17°C (55-65°F) and you must ensure they are adequately ventilated.  Watering is extremely important and care should be taken, during winter only apply water sparingly and then only moderately when plants are in full growth in summer. 

Below are some of the banksias to look out for and if you can provide sufficient frost protection will be a valuable asset to your garden.  The descriptions below are based on their native habits to give a broader picture of the plants and how they are used in the southern hemisphere. 

Banksia integrifolia, (Coast banksia or white honeysuckle) is an evergreen which can grow to 7 m or more.  It is strong growing and thickly branched, the leathery, dark-green leaves have silvery reverses and are very pretty when ruffled by the wind.  The flowers are large, stiff brushes of lemon-yellow are much sought by honey-eating birds, and in autumn its cones are produced.  The coast honeysuckle is adaptable to most soils.

Banksia asplenifolia can reach 1.5-2.5 m x 2 m; the long, toothed, oval leaves are bronze when young; yellow to pale-green flowers and oval cones are produced in autumn or winter; it suits coastal conditions and is frost resistant. 

Banksia ericifolia (heath banksia) is very hardy and has a dense habit that makes this freely branching tall evergreen 3.7 m x 3.4 m useful for screens with its small, bright green, needle-like leaves. The dense, upright, bottlebrush-like spikes, each 10-15cm (4-6in) long, are small tubes of bronze-red or occasionally yellow flowers.  Cylindrical cones appear later in autumn or winter. 

Banksia marginata (silver banksia) reach 1-4 m x 3 m or more; the silver reverses on variable shaped leaves are attractive in the wind and the many small bright-yellow flower spikes appear from spring to autumn.  It produces a variety of forms from stunted shrubs to tall trees which are useful on the coast in frost-prone areas 

Banksia robur (swamp banksia) can attain 1-2 m x 2-4 m and is open-branched with long broad leaves the yellow-green flower spikes can be seen all year round and would be an ideal focal point in the garden especially in cold wet soils. 

Banksia baxteri is an evergreen, spreading, open shrub 2m x 3m with leathery, mid-green leaves that are strap- shaped, cut from the midrib into triangular sharply pointed lobes.  It produces dense, spherical heads of small, tubular, yellow flowers in summer. 

The much larger Banksia serrata (saw banksia or red honeysuckle) may reach 10 m x 10 m, its oblong to lance shaped, saw-toothed, leathery leaves are mid- to deep green.  The small, tubular, reddish-budded, cream flowers are covered in silky hairs and they appear in dense, upright, bottlebrush-like spikes, each 10-15cm (4-6in) long, from spring to late summer.  This species is wind and salt resistant and with age becomes bushy shaped. 

Propagation of banksias is usually by seed that is released from the fascinating large cones they produce and is a specialised process.  There a two methods, either the cones should be first heated in an oven and then plunged into cold water for twenty-four hours or soaked in water for several days.  Either way, once the cones are taken from the water they must be dried out rapidly and placed on a sheet of paper, or in a cardboard box, to retain the dispersed seeds. The seeds are sown in sandy soil at 15-17°C (60-65°F) and germination takes between four and eight weeks care should be taken to prevent damping-off by regularly watering with a fungicide. Banksias can also be struck from cuttings of firm shoots placed in well-drained pots of sandy soil in July in a propagator cabinet in temperatures between 13-17°C (55-65°F).