Hardwickia binata

Cultivation Details

Hardwickia binata is a plant of the dry to moist lowland tropics and subtropics, growing mainly in a climate characterized by a long period of drought, scant to moderate rainfall, and intense heat during the hot season^[1]. It it is found at elevations up to 300 metres^[2]. It grows best in areas where annual daytime temperatures are within the range 16 - 38°c, but can tolerate 5 - 46°c^[3]. Mature plants can be killed by temperatures of -2°c or lower, but new growth will be severely damaged at -1°c^[3]. In the cold season, frosts, generally mild, occur only in certain portions of its area of distribution, particularly in low-lying areas^[2]. It prefers a mean annual rainfall in the range 500 - 1,000mm, but tolerates 250 - 1,500mm^[3]. The tree grows best on sandstone, conglomerate, quartzite, granite and schist, with an overlying soil of sandy loam or, very characteristic, a quartzose reddish gravelly sand^[2]. The tree thrives in a dry climate and is capable of establishing itself and growing on dry shallow soil and rocky ground where most other species would succumb^[2]. Young trees can withstand some shade and may even require artificial shading^[2]. Later, the plants are moderately light demanding^[2].The overlying soil does not have to be deep since the taproot has a capacity for growing through fissures in solid rock^[2]. It tolerates acidic to neutral soils^[2]. Prefers a pH in the range 5.5 - 7.5, tolerating 4.5 - 8^[3]. In its natural range, the seedlings are sensitive to drought, while frosts are not severe enough to do any harm^[2]. From the second year onwards, the plants are immune to injury from frost^[2]. A taproot that has the ability to penetrate hard soil and fissures in solid rock develops early in the life of the seedling plant^[2]. The stem usually dies back annually during the early years of developing the taproot^[2]. The tree pollards well even up to a comparatively advanced age, and old pollards when pollarded again almost invariably produce abundant new shoots^[2]. However, the tree coppices poorly^[2]. Old trees, which send out vigorous pollard shoots if cut 1 or 2 metres above the ground, produce no coppice shoots if cut flush with the ground; old pollards when felled at ground level never coppice^[2]. Young shoots are sensitive to fire, but recovery is good^[2]. A nodulating species, but there is considerable doubt about whether it is nitrogen fixing or not^[2].