Eucalyptus gomphocephala

Cultivation Details

Eucalyptus gomphocephala is native to the Mediterranean climate of southwestern Australia, where it is found at elevations up to 30 metres. Summers are hot and dry, with most rainfall occurring in the winter months, there can be a dry season of 4 - 5 months. Mean annual rainfall is within the range 750 - 1,000mm; mean maximum temperature of the hottest month is 25 - 29°c; mean minimum temperature of the coldest month is 4 - 7°c, and there are generally around 1 - 15 frosts a year^[1]. When dormant, the plant can survive temperatures down to about -4°c, but young growth is more tender and can be severely damaged at 0°c^[2]. Requires a sunny position, succeeding in a range of light to medium-textured, well-drained soils of low to moderate fertility^[2]. Tolerant of moderately saline soils^[2]. Prefers a pH in the range 6.5 - 7.5, tolerating 6 - 9^[2]. Tolerant of salt-laden winds^[2]. Established plants are drought tolerant^[2]. Trees produce epicormic buds along the main trunk and respond well to coppicing. For firewood production, rotations of 7 - 10 years are used^{[2, 3]}. A maximum annual wood production of 44 cubic metres per hectare has been obtained on irrigated fertile soils in Morocco. On more normal sites, annual productions of 6 - 15 cubic metres per hectare are typical^[2]. The tree is a popular introduction in many countries on sands or sandy loams with a high percentage of lime or with a limestone parent material^[1]. This species has proved outstanding for planting in winter-rainfall conditions on calcareous soils on which some other species such as Eucalyptus carnaldulensis become chlorotic. It has shown considerable plasticity in acclimatization to drier conditions than occur within its natural range, but should not be planted in situations which are too cold (absolute minimum less than 4°c) or which suffer from extreme aridity (rainfall less than 300mm) Its tolerance of dry soils is due to its rooting system which combines a deep taproot (to depth of 3 metres if the water table is that deep) and extensive surface rooting up to a radius of 8 - 12 metres. The taproot absorbs moisture from the deeper soil layers during the dry season, while the surface roots make possible an immediate use of the first rains in winter. The species is wind-firm and hence suitable for planting as a windbreak. It is easy to raise in the nursery and regenerates readily from coppice, but it is frequently crooked or forked, especially during the first (seedling) rotation^[1]. Eucalyptus species have not adopted a deciduous habit and continue to grow until it is too cold for them to do so. This makes them more susceptible to damage from sudden cold snaps. If temperature fluctuations are more gradual, as in a woodland for example, the plants have the opportunity to stop growing and become dormant, thus making them more cold resistant. A deep mulch around the roots to prevent the soil from freezing also helps the trees to survive cold conditions^[4]. Many members of this genus are remarkably adaptable however, and there can be a dramatic increase in the hardiness of subsequent generations from the seed of survivors growing in temperate zones^[4].