Although the nutrition and fertilization of container-grown ornamental plants during production have been extensively studied, very little is known about the fertilizer requirements of container-grown ornamental plants following transplanting into the landscape. Because landscape soils differ greatly in physical and chemical properties from the substrates used in container production, the nutritional requirements are therefore also quite different. In the southeastern United States, pine bark is a major component in container substrates. Plants grown in pine bark substrates tend to have high nitrogen requirements due to the immobilization of N by microbes that degrade pine bark (Prasad, 1980). Thus, woody ornamental plants grow best in such substrates when provided with high N analysis fertilizers (Jackson et al., 2008; Wright and Niemiera, 1987).
Landscape soils vary greatly by region, and even locally, in their physical and chemical properties. Landscape soils in many parts of the United States are sufficiently fertile that routine fertilization of established woody ornamental plants is not required (Harris et al., 2004; Neely, 1980; Perry and Hickman, 1992). In other areas, such as the highly leached sandy soils of the southern Atlantic coastal plain, nutrient deficiencies are common and corrective or prophylactic fertilization may be needed (Gilman, 1987; Gilman et al., 2000). Palms (Arecaceae) in particular, which have high potassium, magnesium, and micronutrient requirements, usually exhibit some degree of K or other nutrient deficiency symptoms when grown on these soils (Broschat and Meerow, 2000). High N fertilization has been shown to exacerbate K and Mg deficiencies in these plants and thus recommended landscape fertilizers have lower N:K ratios than those used for turfgrass or container production of ornamentals, including palms (Broschat, 2005; Broschat et al., 2008).
Broschat et al. (2008) observed that container-grown areca palm plants became increasingly N deficient in appearance during the first 6 to 8 months following transplanting into a sandy soil in southeastern Florida. Such plants, even when fertilized as recommended for established palms in the landscape, showed little evidence of growth during this establishment period. Because the root systems of transplanted plants are believed to remain largely confined to the container substrate in which they had been growing during the first season after transplanting, N draw-down in the root ball could result in reduced growth rate and, therefore, slow establishment in the landscape unless the original container substrate root ball continues to receive the high N fertilizers required for these substrates. The purpose of this study was to determine if increasing the N content of fertilizers applied to transplanted container-grown areca palm and chinese hibiscus plants could accelerate the rate of establishment without exacerbating K and/or Mg deficiencies.
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