Eucalyptus grandis

Cultivation Details

Eucalyptus grandis is a plant of the humid subtropical and tropical regions of eastern Australia, it grows in areas with mean minimum temperatures during the coldest month ranging from 2 - 10°c and mean maximums near 29°c during the hottest month^[1]. Rainfall averages 1,020 - 1,780mm, concentrated in the summer but with monthly precipitation during the dry season of at least 20mm^[1]. Plants can experience occasional frosts in the high parts of its range^[1]. So long as the temperature drops gradually over a period of days, the tree can tolerate frost of -3°c, but rapid falls to that temperature can cause severe damage^[1]. When dormant, the plant can survive temperatures down to about -8°c, but young growth is more tender and can be severely damaged at -1°c^[2]. Requires a sunny position and a deep, free-draining soil, growing best on fertile loam or clay-loam soils, but it will also perform well on lighter sandy soils, provided these are deep enough^{[3, 1]}. Prefers a pH in the range 5.5 - 6.5, tolerating 5 - 7.5^[2]. Whilst most Eucalyptus species, grown in small numbers outside their native range, can be an attractive and useful addition to the landscape, certain species (including this one) are more problematic. When grown in monocultures, especially outside their native range, they can become an environmental disaster. They are voracious, especially in their use of water; they are allelopathic, inhibiting the growth of the native flora; they reduce habitats for native fauna; and encourage the worst possible attitudes to land use and conservation^[4]. A very fast-growing tree, height increase in young trees of 2 metres per year are common, with some trees averaging 4 metres for the first 10 years or more^{[3, 5]}. Trees respond well to coppicing^[1]. When grown for pulpwood, fuel wood and timber for mining, a 6 - 10 year rotation is common. In most countries, no thinning is done on these short rotations^[1]. For saw logs, a rotation of 30 years is recommended with thinning at ages 7, 11 and 15 years, leaving a final stocking of 250 stems/ha^[1]. The use of boron to reduce die-back and improve the growth rate is essential^[1]. For most types of products, one seedling rotation, followed by at least two coppice rotations, is common practice^[1]. Trees normally produce a strong taproot, with few laterals^[6]. Trees can commence flowering when 4 - 5 years old^[5]. Under natural conditions, the tree bears heavy seed crops every 2 - 3 years^[1]. A fully mature tree can produce 2 kg of seed annually^[1]. This species often hybridizes with the closely related Eucalyptus saligna, from which it is distinguished most easily by the shape ofthe fruit valves^[5]. 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].